Include a stripped-down version of FLTK in tree and add a USE_INCLUDED_FLTK option to build against it.


git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4603 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/common/fltk/src/Fl_Text_Display.cxx b/common/fltk/src/Fl_Text_Display.cxx
new file mode 100644
index 0000000..a795035
--- /dev/null
+++ b/common/fltk/src/Fl_Text_Display.cxx
@@ -0,0 +1,3795 @@
+//
+// "$Id: Fl_Text_Display.cxx 8808 2011-06-16 13:31:25Z manolo $"
+//
+// Copyright 2001-2010 by Bill Spitzak and others.
+// Original code Copyright Mark Edel.  Permission to distribute under
+// the LGPL for the FLTK library granted by Mark Edel.
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU Library General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+// USA.
+//
+// Please report all bugs and problems on the following page:
+//
+//     http://www.fltk.org/str.php
+//
+
+// TODO: rendering of the "optional hyphen"
+// TODO: make line numbering work again
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <FL/fl_utf8.h>
+#include "flstring.h"
+#include <limits.h>
+#include <ctype.h>
+#include <FL/Fl.H>
+#include <FL/Fl_Text_Buffer.H>
+#include <FL/Fl_Text_Display.H>
+#include <FL/Fl_Window.H>
+#include <FL/Fl_Printer.H>
+
+#undef min
+#undef max
+
+// Text area margins.  Left & right margins should be at least 3 so that
+// there is some room for the overhanging parts of the cursor!
+#define TOP_MARGIN 1
+#define BOTTOM_MARGIN 1
+#define LEFT_MARGIN 3
+#define RIGHT_MARGIN 3
+
+#define NO_HINT -1
+
+/* Masks for text drawing methods.  These are or'd together to form an
+ integer which describes what drawing calls to use to draw a string */
+#define FILL_MASK         0x0100
+#define SECONDARY_MASK    0x0200
+#define PRIMARY_MASK      0x0400
+#define HIGHLIGHT_MASK    0x0800
+#define BG_ONLY_MASK      0x1000
+#define TEXT_ONLY_MASK    0x2000
+#define STYLE_LOOKUP_MASK   0xff
+
+/* Maximum displayable line length (how many characters will fit across the
+ widest window).  This amount of memory is temporarily allocated from the
+ stack in the draw_vline() method for drawing strings */
+#define MAX_DISP_LINE_LEN 1000
+
+static int max( int i1, int i2 );
+static int min( int i1, int i2 );
+static int countlines( const char *string );
+
+/* The variables below are used in a timer event to allow smooth
+ scrolling of the text area when the pointer has left the area. */
+static int scroll_direction = 0;
+static int scroll_amount = 0;
+static int scroll_y = 0;
+static int scroll_x = 0;
+
+// CET - FIXME
+#define TMPFONTWIDTH 6
+
+
+
+/**  
+ \brief Creates a new text display widget.
+ 
+ \param X, Y, W, H position and size of widget
+ \param l label text, defaults to none
+ */
+Fl_Text_Display::Fl_Text_Display(int X, int Y, int W, int H, const char* l)
+: Fl_Group(X, Y, W, H, l) {
+  int i;
+  
+  mMaxsize = 0;
+  damage_range1_start = damage_range1_end = -1;
+  damage_range2_start = damage_range2_end = -1;
+  dragPos = dragging = 0;
+  dragType = DRAG_CHAR;
+  display_insert_position_hint = 0;
+  shortcut_ = 0;
+  
+  color(FL_BACKGROUND2_COLOR, FL_SELECTION_COLOR);
+  box(FL_DOWN_FRAME);
+  textsize(FL_NORMAL_SIZE);
+  textcolor(FL_FOREGROUND_COLOR);
+  textfont(FL_HELVETICA);
+  set_flag(SHORTCUT_LABEL);
+  
+  text_area.x = 0;
+  text_area.y = 0;
+  text_area.w = 0;
+  text_area.h = 0;
+  
+  mVScrollBar = new Fl_Scrollbar(0,0,1,1);
+  mVScrollBar->callback((Fl_Callback*)v_scrollbar_cb, this);
+  mHScrollBar = new Fl_Scrollbar(0,0,1,1);
+  mHScrollBar->callback((Fl_Callback*)h_scrollbar_cb, this);
+  mHScrollBar->type(FL_HORIZONTAL);
+  
+  end();
+  
+  scrollbar_width(Fl::scrollbar_size());
+  scrollbar_align(FL_ALIGN_BOTTOM_RIGHT);
+  
+  mCursorOn = 0;
+  mCursorPos = 0;
+  mCursorOldY = -100;
+  mCursorToHint = NO_HINT;
+  mCursorStyle = NORMAL_CURSOR;
+  mCursorPreferredXPos = -1;
+  mBuffer = 0;
+  mFirstChar = 0;
+  mLastChar = 0;
+  mNBufferLines = 0;
+  mTopLineNum = mTopLineNumHint = 1;
+  mAbsTopLineNum = 1;
+  mNeedAbsTopLineNum = 0;
+  mHorizOffset = mHorizOffsetHint = 0;
+  
+  mCursor_color = FL_FOREGROUND_COLOR;
+  
+  mStyleBuffer = 0;
+  mStyleTable = 0;
+  mNStyles = 0;
+  mNVisibleLines = 1;
+  mLineStarts = new int[mNVisibleLines];
+  mLineStarts[0] = 0;
+  for (i=1; i<mNVisibleLines; i++)
+    mLineStarts[i] = -1;
+  mSuppressResync = 0;
+  mNLinesDeleted = 0;
+  mModifyingTabDistance = 0;
+  
+  mUnfinishedStyle = 0;
+  mUnfinishedHighlightCB = 0;
+  mHighlightCBArg = 0;
+  
+  mLineNumLeft = mLineNumWidth = 0;
+  mContinuousWrap = 0;
+  mWrapMarginPix = 0;
+  mSuppressResync = mNLinesDeleted = mModifyingTabDistance = 0;
+}
+
+
+
+/**
+ Free a text display and release its associated memory.
+ 
+ Note, the text BUFFER that the text display displays is a separate
+ entity and is not freed, nor are the style buffer or style table.
+ */
+Fl_Text_Display::~Fl_Text_Display() {
+  if (scroll_direction) {
+    Fl::remove_timeout(scroll_timer_cb, this);
+    scroll_direction = 0;
+  }
+  if (mBuffer) {
+    mBuffer->remove_modify_callback(buffer_modified_cb, this);
+    mBuffer->remove_predelete_callback(buffer_predelete_cb, this);
+  }
+  if (mLineStarts) delete[] mLineStarts;
+}
+
+
+
+/**  
+ Attach a text buffer to display, replacing the current buffer (if any)
+ \param buf attach this text buffer
+ */
+void Fl_Text_Display::buffer( Fl_Text_Buffer *buf ) {
+  /* If the text display is already displaying a buffer, clear it off
+   of the display and remove our callback from it */
+  if ( buf == mBuffer) return;
+  if ( mBuffer != 0 ) {
+    // we must provide a copy of the buffer that we are deleting!
+    char *deletedText = mBuffer->text();
+    buffer_modified_cb( 0, 0, mBuffer->length(), 0, deletedText, this );
+    free(deletedText);
+    mNBufferLines = 0;
+    mBuffer->remove_modify_callback( buffer_modified_cb, this );
+    mBuffer->remove_predelete_callback( buffer_predelete_cb, this );
+  }
+  
+  /* Add the buffer to the display, and attach a callback to the buffer for
+   receiving modification information when the buffer contents change */
+  mBuffer = buf;
+  if (mBuffer) {
+    mBuffer->add_modify_callback( buffer_modified_cb, this );
+    mBuffer->add_predelete_callback( buffer_predelete_cb, this );
+    
+    /* Update the display */
+    buffer_modified_cb( 0, buf->length(), 0, 0, 0, this );
+  }
+  
+  /* Resize the widget to update the screen... */
+  resize(x(), y(), w(), h());
+}
+
+
+
+/**   
+ \brief Attach (or remove) highlight information in text display and redisplay.
+ 
+ Highlighting information consists of a style buffer which parallels the
+ normal text buffer, but codes font and color information for the display;
+ a style table which translates style buffer codes (indexed by buffer
+ character - 'A') into fonts and colors; and a callback mechanism for
+ as-needed highlighting, triggered by a style buffer entry of
+ "unfinishedStyle".  Style buffer can trigger additional redisplay during
+ a normal buffer modification if the buffer contains a primary Fl_Text_Selection
+ (see extendRangeForStyleMods for more information on this protocol).
+ 
+ Style buffers, tables and their associated memory are managed by the caller.
+ 
+ Styles are ranged from 65 ('A') to 126.
+ 
+ \param styleBuffer this buffer works in parallel to the text buffer. For every
+   character in the text buffer, the stye buffer has a byte at the same offset 
+   that contains an index into an array of possible styles. 
+ \param styleTable a list of styles indexed by the style buffer
+ \param nStyles number of styles in the style table
+ \param unfinishedStyle if this style is found, the callback below is called
+ \param unfinishedHighlightCB if a character with an unfinished style is found,
+   this callback will be called
+ \param cbArg and optional argument for the callback above, usually a pointer
+   to the Text Display.
+ */
+void Fl_Text_Display::highlight_data(Fl_Text_Buffer *styleBuffer,
+                                     const Style_Table_Entry *styleTable,
+                                     int nStyles, char unfinishedStyle,
+                                     Unfinished_Style_Cb unfinishedHighlightCB,
+                                     void *cbArg ) {
+  mStyleBuffer = styleBuffer;
+  mStyleTable = styleTable;
+  mNStyles = nStyles;
+  mUnfinishedStyle = unfinishedStyle;
+  mUnfinishedHighlightCB = unfinishedHighlightCB;
+  mHighlightCBArg = cbArg;
+  mColumnScale = 0;
+  
+  mStyleBuffer->canUndo(0);
+  damage(FL_DAMAGE_EXPOSE);
+}
+
+
+
+/**
+ \brief Find the longest line of all visible lines.
+ \return the width of the longest visible line in pixels
+ */
+int Fl_Text_Display::longest_vline() const {
+  int longest = 0;
+  for (int i = 0; i < mNVisibleLines; i++)
+    longest = max(longest, measure_vline(i));
+  return longest;
+}
+
+
+
+/**
+ \brief Change the size of the displayed text area.
+ Calling this function will trigger a recalculation of all lines visible and
+ of all scrollbar sizes.
+ \param X, Y, W, H new position and size of this widget
+ */
+void Fl_Text_Display::resize(int X, int Y, int W, int H) {
+#ifdef DEBUG
+  printf("Fl_Text_Display::resize(X=%d, Y=%d, W=%d, H=%d)\n", X, Y, W, H);
+#endif // DEBUG
+  const int oldWidth = w();
+#ifdef DEBUG
+  printf("    oldWidth=%d, mContinuousWrap=%d, mWrapMargin=%d\n", oldWidth, mContinuousWrap, mWrapMargin);
+#endif // DEBUG
+  Fl_Widget::resize(X,Y,W,H);
+  if (!buffer()) return;
+  X += Fl::box_dx(box());
+  Y += Fl::box_dy(box());
+  W -= Fl::box_dw(box());
+  H -= Fl::box_dh(box());
+  
+  text_area.x = X+LEFT_MARGIN;
+  text_area.y = Y+TOP_MARGIN;
+  text_area.w = W-LEFT_MARGIN-RIGHT_MARGIN;
+  text_area.h = H-TOP_MARGIN-BOTTOM_MARGIN;
+  int i;
+  
+  /* Find the new maximum font height for this text display */
+  for (i = 0, mMaxsize = fl_height(textfont(), textsize()); i < mNStyles; i++)
+    mMaxsize = max(mMaxsize, fl_height(mStyleTable[i].font, mStyleTable[i].size));
+  
+  // did we have scrollbars initially?
+  unsigned int hscrollbarvisible = mHScrollBar->visible();
+  unsigned int vscrollbarvisible = mVScrollBar->visible();
+  
+  // try without scrollbars first
+  mVScrollBar->clear_visible();
+  mHScrollBar->clear_visible();
+  
+  for (int again = 1; again;) {
+    again = 0;
+    /* In continuous wrap mode, a change in width affects the total number of
+     lines in the buffer, and can leave the top line number incorrect, and
+     the top character no longer pointing at a valid line start */
+    if (mContinuousWrap && !mWrapMarginPix && W!=oldWidth) {
+      int oldFirstChar = mFirstChar;
+      mNBufferLines = count_lines(0, buffer()->length(), true);
+      mFirstChar = line_start(mFirstChar);
+      mTopLineNum = count_lines(0, mFirstChar, true)+1;
+      absolute_top_line_number(oldFirstChar);      
+#ifdef DEBUG
+      printf("    mNBufferLines=%d\n", mNBufferLines);
+#endif // DEBUG
+    }
+    
+    /* reallocate and update the line starts array, which may have changed
+     size and / or contents.  */
+    int nvlines = (text_area.h + mMaxsize - 1) / mMaxsize;
+    if (nvlines < 1) nvlines = 1;
+    if (mNVisibleLines != nvlines) {
+      mNVisibleLines = nvlines;
+      if (mLineStarts) delete[] mLineStarts;
+      mLineStarts = new int [mNVisibleLines];
+    }
+    
+    calc_line_starts(0, mNVisibleLines);
+    calc_last_char();
+    
+    // figure the scrollbars
+    if (scrollbar_width()) {
+      /* Decide if the vertical scrollbar needs to be visible */
+      if (scrollbar_align() & (FL_ALIGN_LEFT|FL_ALIGN_RIGHT) &&
+          mNBufferLines >= mNVisibleLines - 1)
+      {
+        mVScrollBar->set_visible();
+        if (scrollbar_align() & FL_ALIGN_LEFT) {
+          text_area.x = X+scrollbar_width()+LEFT_MARGIN;
+          text_area.w = W-scrollbar_width()-LEFT_MARGIN-RIGHT_MARGIN;
+          mVScrollBar->resize(X, text_area.y-TOP_MARGIN, scrollbar_width(),
+                              text_area.h+TOP_MARGIN+BOTTOM_MARGIN);
+        } else {
+          text_area.x = X+LEFT_MARGIN;
+          text_area.w = W-scrollbar_width()-LEFT_MARGIN-RIGHT_MARGIN;
+          mVScrollBar->resize(X+W-scrollbar_width(), text_area.y-TOP_MARGIN,
+                              scrollbar_width(), text_area.h+TOP_MARGIN+BOTTOM_MARGIN);
+        }
+      }
+      
+      /*
+       Decide if the horizontal scrollbar needs to be visible.  If there
+       is a vertical scrollbar, a horizontal is always created too.  This
+       is because the alternatives are unattractive:
+       * Dynamically creating a horizontal scrollbar based on the currently
+       visible lines is what the original nedit does, but it always wastes
+       space for the scrollbar even when it's not used.  Since the FLTK
+       widget dynamically allocates the space for the scrollbar and
+       rearranges the widget to make room for it, this would create a very
+       visually displeasing "bounce" effect when the vertical scrollbar is
+       dragged.  Trust me, I tried it and it looks really bad.
+       * The other alternative would be to keep track of what the longest
+       line in the entire buffer is and base the scrollbar on that.  I
+       didn't do this because I didn't see any easy way to do that using
+       the nedit code and this could involve a lengthy calculation for
+       large buffers.  If an efficient and non-costly way of doing this
+       can be found, this might be a way to go.
+       */
+      /* WAS: Suggestion: Try turning the horizontal scrollbar on when
+       you first see a line that is too wide in the window, but then
+       don't turn it off (ie mix both of your solutions). */
+      if (scrollbar_align() & (FL_ALIGN_TOP|FL_ALIGN_BOTTOM) &&
+          (mVScrollBar->visible() || longest_vline() > text_area.w))
+      {
+        if (!mHScrollBar->visible()) {
+          mHScrollBar->set_visible();
+          again = 1; // loop again to see if we now need vert. & recalc sizes
+        }
+        if (scrollbar_align() & FL_ALIGN_TOP) {
+          text_area.y = Y + scrollbar_width()+TOP_MARGIN;
+          text_area.h = H - scrollbar_width()-TOP_MARGIN-BOTTOM_MARGIN;
+          mHScrollBar->resize(text_area.x-LEFT_MARGIN, Y,
+                              text_area.w+LEFT_MARGIN+RIGHT_MARGIN, scrollbar_width());
+        } else {
+          text_area.y = Y+TOP_MARGIN;
+          text_area.h = H - scrollbar_width()-TOP_MARGIN-BOTTOM_MARGIN;
+          mHScrollBar->resize(text_area.x-LEFT_MARGIN, Y+H-scrollbar_width(),
+                              text_area.w+LEFT_MARGIN+RIGHT_MARGIN, scrollbar_width());
+        }
+      }
+    }
+  }
+  
+  // user request to change viewport
+  if (mTopLineNumHint != mTopLineNum || mHorizOffsetHint != mHorizOffset)
+    scroll_(mTopLineNumHint, mHorizOffsetHint);
+  
+  // everything will fit in the viewport
+  if (mNBufferLines < mNVisibleLines || mBuffer == NULL || mBuffer->length() == 0) {
+    scroll_(1, mHorizOffset);
+  /* if empty lines become visible, there may be an opportunity to
+   display more text by scrolling down */
+  } else {
+    while (   mNVisibleLines>=2
+           && (mLineStarts[mNVisibleLines-2]==-1) 
+           && scroll_(mTopLineNum-1, mHorizOffset))
+    { }
+  }
+  
+  // user request to display insert position
+  if (display_insert_position_hint)
+    display_insert();
+  
+  // in case horizontal offset is now greater than longest line
+  int maxhoffset = max(0, longest_vline()-text_area.w);
+  if (mHorizOffset > maxhoffset)
+    scroll_(mTopLineNumHint, maxhoffset);
+  
+  mTopLineNumHint = mTopLineNum;
+  mHorizOffsetHint = mHorizOffset;
+  display_insert_position_hint = 0;
+  
+  if (mContinuousWrap ||
+      hscrollbarvisible != mHScrollBar->visible() ||
+      vscrollbarvisible != mVScrollBar->visible())
+    redraw();
+  
+  update_v_scrollbar();
+  update_h_scrollbar();
+}
+
+
+
+/**
+ \brief Refresh a rectangle of the text display.  
+ \param left, top are in coordinates of the text drawing window.
+ \param width, height size in pixels 
+ */
+void Fl_Text_Display::draw_text( int left, int top, int width, int height ) {
+  int fontHeight, firstLine, lastLine, line;
+  
+  /* find the line number range of the display */
+  fontHeight = mMaxsize ? mMaxsize : textsize_;
+  firstLine = ( top - text_area.y - fontHeight + 1 ) / fontHeight;
+  lastLine = ( top + height - text_area.y ) / fontHeight + 1;
+  
+  fl_push_clip( left, top, width, height );
+  
+  /* draw the lines */
+  for ( line = firstLine; line <= lastLine; line++ )
+    draw_vline( line, left, left + width, 0, INT_MAX );
+  
+  /* draw the line numbers if exposed area includes them */
+  if (mLineNumWidth != 0 && left <= mLineNumLeft + mLineNumWidth)
+    draw_line_numbers(false);
+  
+  fl_pop_clip();
+}
+
+
+
+/**  
+ \brief Marks text from start to end as needing a redraw.
+ This function will trigger a damage event and later a redraw of parts of 
+ the widget.
+ \param startpos index of first character needing redraw
+ \param endpos index after last character needing redraw
+ */
+void Fl_Text_Display::redisplay_range(int startpos, int endpos) {
+  IS_UTF8_ALIGNED2(buffer(), startpos)
+  IS_UTF8_ALIGNED2(buffer(), endpos)
+  
+  if (damage_range1_start == -1 && damage_range1_end == -1) {
+    damage_range1_start = startpos;
+    damage_range1_end = endpos;
+  } else if ((startpos >= damage_range1_start && startpos <= damage_range1_end) ||
+             (endpos >= damage_range1_start && endpos <= damage_range1_end)) {
+    damage_range1_start = min(damage_range1_start, startpos);
+    damage_range1_end = max(damage_range1_end, endpos);
+  } else if (damage_range2_start == -1 && damage_range2_end == -1) {
+    damage_range2_start = startpos;
+    damage_range2_end = endpos;
+  } else {
+    damage_range2_start = min(damage_range2_start, startpos);
+    damage_range2_end = max(damage_range2_end, endpos);
+  }
+  damage(FL_DAMAGE_SCROLL);
+}
+
+
+
+/**
+ \brief Draw a range of text.
+
+ Refresh all of the text between buffer positions \p startpos and
+ \p endpos not including the character at the position \p endpos.
+
+ If \p endpos points beyond the end of the buffer, refresh the whole display
+ after \p startpos, including blank lines which are not technically part of
+ any range of characters.
+
+ \param startpos index of first character to draw
+ \param endpos index after last character to draw
+ */
+void Fl_Text_Display::draw_range(int startpos, int endpos) {
+  startpos = buffer()->utf8_align(startpos);
+  endpos = buffer()->utf8_align(endpos);
+  
+  int i, startLine, lastLine, startIndex, endIndex;
+  
+  /* If the range is outside of the displayed text, just return */
+  if ( endpos < mFirstChar || ( startpos > mLastChar && !empty_vlines() ) ) 
+    return;
+  
+  /* Clean up the starting and ending values */
+  if ( startpos < 0 ) startpos = 0;
+  if ( startpos > mBuffer->length() ) startpos = mBuffer->length();
+  if ( endpos < 0 ) endpos = 0;
+  if ( endpos > mBuffer->length() ) endpos = mBuffer->length();
+  
+  /* Get the starting and ending lines */
+  if ( startpos < mFirstChar )
+    startpos = mFirstChar;
+  if ( !position_to_line( startpos, &startLine ) )
+    startLine = mNVisibleLines - 1;
+  if ( endpos >= mLastChar ) {
+    lastLine = mNVisibleLines - 1;
+  } else {
+    if ( !position_to_line( endpos, &lastLine ) ) {
+      /* shouldn't happen */
+      lastLine = mNVisibleLines - 1;
+    }
+  }
+  
+  /* Get the starting and ending positions within the lines */
+  startIndex = mLineStarts[ startLine ] == -1 ? 0 : startpos - mLineStarts[ startLine ];
+  if ( endpos >= mLastChar )
+    endIndex = INT_MAX;
+  else if ( mLineStarts[ lastLine ] == -1 )
+    endIndex = 0;
+  else
+    endIndex = endpos - mLineStarts[ lastLine ];
+  
+  /* If the starting and ending lines are the same, redisplay the single
+   line between "start" and "end" */
+  if ( startLine == lastLine ) {
+    draw_vline( startLine, 0, INT_MAX, startIndex, endIndex );
+    return;
+  }
+
+  /* Redisplay the first line from "start" */
+  draw_vline( startLine, 0, INT_MAX, startIndex, INT_MAX );
+
+  /* Redisplay the lines in between at their full width */
+  for ( i = startLine + 1; i < lastLine; i++ )
+    draw_vline( i, 0, INT_MAX, 0, INT_MAX );
+
+  /* Redisplay the last line to "end" */
+  draw_vline( lastLine, 0, INT_MAX, 0, endIndex );
+}
+
+
+
+/** 
+ \brief Sets the position of the text insertion cursor for text display.
+ Move the insertion cursor in front of the character at \p newPos.
+ This function may trigger a redraw.
+ \param newPos new caret position
+ */
+void Fl_Text_Display::insert_position( int newPos ) {
+  IS_UTF8_ALIGNED2(buffer(), newPos)
+  
+  /* make sure new position is ok, do nothing if it hasn't changed */
+  if ( newPos == mCursorPos ) return;
+  if ( newPos < 0 ) newPos = 0;
+  if ( newPos > mBuffer->length() ) newPos = mBuffer->length();
+  
+  /* cursor movement cancels vertical cursor motion column */
+  mCursorPreferredXPos = -1;
+  
+  /* erase the cursor at its previous position */
+  redisplay_range(buffer()->prev_char_clipped(mCursorPos), buffer()->next_char(mCursorPos));
+  
+  mCursorPos = newPos;
+  
+  /* draw cursor at its new position */
+  redisplay_range(buffer()->prev_char_clipped(mCursorPos), buffer()->next_char(mCursorPos));
+}
+
+
+
+/** 
+ \brief Shows the text cursor.
+ This function may trigger a redraw.
+ \param b show(1) or hide(0) the text cursor (caret).
+ */
+void Fl_Text_Display::show_cursor(int b) {
+  mCursorOn = b;
+  redisplay_range(buffer()->prev_char_clipped(mCursorPos), buffer()->next_char(mCursorPos));
+}
+
+
+
+/**
+ \brief Sets the text cursor style.
+ Sets the text cursor style to one of the following:
+ 
+ \li Fl_Text_Display::NORMAL_CURSOR - Shows an I beam.
+ \li Fl_Text_Display::CARET_CURSOR - Shows a caret under the text.
+ \li Fl_Text_Display::DIM_CURSOR - Shows a dimmed I beam.
+ \li Fl_Text_Display::BLOCK_CURSOR - Shows an unfilled box around the current
+      character.
+ \li Fl_Text_Display::HEAVY_CURSOR - Shows a thick I beam.
+ 
+ This call also switches the cursor on and may trigger a redraw.
+ 
+ \param style new cursor style
+ */
+void Fl_Text_Display::cursor_style(int style) {
+  mCursorStyle = style;
+  if (mCursorOn) show_cursor();
+}
+
+
+
+/**
+ \brief Set the new text wrap mode.
+ 
+ If \p wrap mode is not zero, this call enables automatic word wrapping at column
+ \p wrapMargin. Word-wrapping does not change the text buffer itself, only the way
+ the text is displayed. Different Text Displays can have different wrap modes,
+ even if they share the same Text Buffer.
+
+ \param wrap new wrap mode is WRAP_NONE (don't wrap text at all), WRAP_AT_COLUMN
+      (wrap text at the given text column), WRAP_AT_PIXEL (wrap text at a pixel 
+      position), or WRAP_AT_BOUNDS (wrap text so that it fits into the 
+      widget width)
+ \param wrapMargin in WRAP_AT_COLUMN mode, text will wrap at the n'th character.
+      For variable width fonts, an average character width is calculated. The
+      column width is calculated using the current textfont or the first style
+      when this function is called. If the font size changes, this function
+      must be called again. In WRAP_AT_PIXEL mode, this is the pixel position.
+ \todo we need new wrap modes to wrap at the window edge and based on pixel width
+   or average character width.
+ */
+void Fl_Text_Display::wrap_mode(int wrap, int wrapMargin) {
+  switch (wrap) {
+    case WRAP_NONE: 
+      mWrapMarginPix = 0;
+      mContinuousWrap = 0;
+      break;
+    case WRAP_AT_COLUMN: 
+    default:
+      mWrapMarginPix = int(col_to_x(wrapMargin));
+      mContinuousWrap = 1;
+      break;
+    case WRAP_AT_PIXEL: 
+      mWrapMarginPix = wrapMargin;
+      mContinuousWrap = 1;
+      break;
+    case WRAP_AT_BOUNDS: 
+      mWrapMarginPix = 0;
+      mContinuousWrap = 1;
+      break;
+  }
+  
+  if (buffer()) {
+    /* wrapping can change the total number of lines, re-count */
+    mNBufferLines = count_lines(0, buffer()->length(), true);
+    
+    /* changing wrap margins or changing from wrapped mode to non-wrapped
+     can leave the character at the top no longer at a line start, and/or
+     change the line number */
+    mFirstChar = line_start(mFirstChar);
+    mTopLineNum = count_lines(0, mFirstChar, true) + 1;
+    
+    reset_absolute_top_line_number();
+    
+    /* update the line starts array */
+    calc_line_starts(0, mNVisibleLines);
+    calc_last_char();
+  } else {
+    // No buffer, so just clear the state info for later...
+    mNBufferLines  = 0;
+    mFirstChar     = 0;
+    mTopLineNum    = 1;
+    mAbsTopLineNum = 0;
+  }
+  
+  resize(x(), y(), w(), h());
+}
+
+
+
+/**
+ \brief Inserts "text" at the current cursor location.  
+ 
+ This has the same effect as inserting the text into the buffer using BufInsert 
+ and then moving the insert position after the newly inserted text, except
+ that it's optimized to do less redrawing.
+ 
+ \param text new text in UTF-8 encoding.
+ */
+void Fl_Text_Display::insert(const char* text) {
+  IS_UTF8_ALIGNED2(buffer(), mCursorPos)
+  IS_UTF8_ALIGNED(text)
+  
+  int pos = mCursorPos;
+  
+  mCursorToHint = pos + strlen( text );
+  mBuffer->insert( pos, text );
+  mCursorToHint = NO_HINT;
+}
+
+
+
+/**  
+ \brief Replaces text at the current insert position.
+ \param text new text in UTF-8 encoding
+ 
+ \todo Unicode? Find out exactly what we do here and simplify.
+ */
+void Fl_Text_Display::overstrike(const char* text) {
+  IS_UTF8_ALIGNED2(buffer(), mCursorPos)
+  IS_UTF8_ALIGNED(text)
+  
+  int startPos = mCursorPos;
+  Fl_Text_Buffer *buf = mBuffer;
+  int lineStart = buf->line_start( startPos );
+  int textLen = strlen( text );
+  int i, p, endPos, indent, startIndent, endIndent;
+  const char *c;
+  unsigned int ch;
+  char *paddedText = NULL;
+  
+  /* determine how many displayed character positions are covered */
+  startIndent = mBuffer->count_displayed_characters( lineStart, startPos );
+  indent = startIndent;
+  for ( c = text; *c != '\0'; c += fl_utf8len1(*c) )
+    indent++;
+  endIndent = indent;
+  
+  /* find which characters to remove, and if necessary generate additional
+   padding to make up for removed control characters at the end */
+  indent = startIndent;
+  for ( p = startPos; ; p=buffer()->next_char(p) ) {
+    if ( p == buf->length() )
+      break;
+    ch = buf->char_at( p );
+    if ( ch == '\n' )
+      break;
+    indent++;
+    if ( indent == endIndent ) {
+      p++;
+      break;
+    } else if ( indent > endIndent ) {
+      if ( ch != '\t' ) {
+        p++;
+        paddedText = new char [ textLen + FL_TEXT_MAX_EXP_CHAR_LEN + 1 ];
+        strcpy( paddedText, text );
+        for ( i = 0; i < indent - endIndent; i++ )
+          paddedText[ textLen + i ] = ' ';
+        paddedText[ textLen + i ] = '\0';
+      }
+      break;
+    }
+  }
+  endPos = p;
+  
+  mCursorToHint = startPos + textLen;
+  buf->replace( startPos, endPos, paddedText == NULL ? text : paddedText );
+  mCursorToHint = NO_HINT;
+  if ( paddedText != NULL )
+    delete [] paddedText;
+}
+
+
+
+/**
+ \brief Convert a character index into a pixel position.
+ 
+ Translate a buffer text position to the XY location where the top left of the 
+ cursor would be positioned to point to that character. Returns 0 if the 
+ position is not displayed because it is \e \b vertically out of view.
+ If the position is horizontally out of view, returns the X coordinate where
+ the position would be if it were visible.
+
+ \param pos character index
+ \param[out] X, Y pixel position of character on screen
+ \return 0 if character vertically out of view, X position otherwise
+ */
+int Fl_Text_Display::position_to_xy( int pos, int* X, int* Y ) const {
+  IS_UTF8_ALIGNED2(buffer(), pos)
+
+  int lineStartPos, fontHeight, lineLen;
+  int visLineNum;
+  
+  /* If position is not displayed, return false */
+  if (pos < mFirstChar || (pos > mLastChar && !empty_vlines())) {
+    return 0;
+  }
+  
+  /* Calculate Y coordinate */
+  if (!position_to_line(pos, &visLineNum)) {
+    return 0;
+  }
+  if (visLineNum < 0 || visLineNum > mNBufferLines) {
+    return 0;
+  }
+  
+  fontHeight = mMaxsize;
+  *Y = text_area.y + visLineNum * fontHeight;
+  
+  /* Get the text, length, and buffer position of the line. If the position
+   is beyond the end of the buffer and should be at the first position on
+   the first empty line, don't try to get or scan the text  */
+  lineStartPos = mLineStarts[visLineNum];
+  if ( lineStartPos == -1 ) {
+    *X = text_area.x - mHorizOffset;
+    return 1;
+  }
+  lineLen = vline_length( visLineNum );
+  *X = text_area.x + handle_vline(GET_WIDTH, lineStartPos, pos-lineStartPos, 0, 0, 0, 0, 0, 0) - mHorizOffset;
+  return 1;
+}
+
+
+
+/**
+ \brief Find the line and column number of position \p pos.  
+
+ This only works for displayed lines. If the line is not displayed, the 
+ function returns 0 (without the mLineStarts array it could turn in to very long
+ calculation involving scanning large amounts of text in the buffer).
+ If continuous wrap mode is on, returns the absolute line number (as opposed
+ to the wrapped line number which is used for scrolling).
+ 
+ \param pos character index
+ \param[out] lineNum absolute (unwrapped) line number
+ \param[out] column character offset to the beginning of the line
+ \return 0 if \p pos is off screen, line number otherwise
+ \todo a column number makes little sense in the UTF-8/variable font width 
+    environment. We will have to further define what exactly we want to return. 
+    Please check the functions that call this particular function.
+ */
+int Fl_Text_Display::position_to_linecol( int pos, int* lineNum, int* column ) const {
+  IS_UTF8_ALIGNED2(buffer(), pos)
+  
+  int retVal;
+  
+  /* In continuous wrap mode, the absolute (non-wrapped) line count is
+   maintained separately, as needed.  Only return it if we're actually
+   keeping track of it and pos is in the displayed text */
+  if (mContinuousWrap) {
+    if (!maintaining_absolute_top_line_number() || pos < mFirstChar || pos > mLastChar)
+      return 0;
+    *lineNum = mAbsTopLineNum + buffer()->count_lines(mFirstChar, pos);
+    *column = buffer()->count_displayed_characters(buffer()->line_start(pos), pos);
+    return 1;
+  }
+  
+  retVal = position_to_line( pos, lineNum );
+  if ( retVal ) {
+    *column = mBuffer->count_displayed_characters( mLineStarts[ *lineNum ], pos );
+    *lineNum += mTopLineNum;
+  }
+  return retVal;
+}
+
+
+
+/**
+ \brief Check if a pixel position is within the primary selection.
+ \param X, Y pixel position to test
+ \return 1 if position (X, Y) is inside of the primary Fl_Text_Selection
+ */
+int Fl_Text_Display::in_selection( int X, int Y ) const {
+  int pos = xy_to_position( X, Y, CHARACTER_POS );
+  IS_UTF8_ALIGNED2(buffer(), pos)
+  Fl_Text_Buffer *buf = mBuffer;
+  return buf->primary_selection()->includes(pos);
+}
+
+
+
+/**
+ \brief Nobody knows what this function does.
+ 
+ Correct a column number based on an unconstrained position (as returned by
+ TextDXYToUnconstrainedPosition) to be relative to the last actual newline
+ in the buffer before the row and column position given, rather than the
+ last line start created by line wrapping.  This is an adapter
+ for rectangular selections and code written before continuous wrap mode,
+ which thinks that the unconstrained column is the number of characters
+ from the last newline.  Obviously this is time consuming, because it
+ invloves character re-counting.
+ 
+ \param row
+ \param column
+ \return something unknown
+ \todo What does this do and how is it useful? Column numbers mean little in 
+    this context. Which functions depend on this one?
+ 
+ \todo Unicode?
+ */
+int Fl_Text_Display::wrapped_column(int row, int column) const {
+  int lineStart, dispLineStart;
+  
+  if (!mContinuousWrap || row < 0 || row > mNVisibleLines)
+    return column;
+  dispLineStart = mLineStarts[row];
+  if (dispLineStart == -1)
+    return column;
+  lineStart = buffer()->line_start(dispLineStart);
+  return column + buffer()->count_displayed_characters(lineStart, dispLineStart);
+}
+
+
+
+/**
+ \brief Nobody knows what this function does.
+ 
+ Correct a row number from an unconstrained position (as returned by
+ TextDXYToUnconstrainedPosition) to a straight number of newlines from the
+ top line of the display.  Because rectangular selections are based on
+ newlines, rather than display wrapping, and anywhere a rectangular selection
+ needs a row, it needs it in terms of un-wrapped lines.
+ 
+ \param row
+ \return something unknown
+ \todo What does this do and how is it useful? Column numbers mean little in 
+ this context. Which functions depend on this one?
+ */
+int Fl_Text_Display::wrapped_row(int row) const {
+  if (!mContinuousWrap || row < 0 || row > mNVisibleLines)
+    return row;
+  return buffer()->count_lines(mFirstChar, mLineStarts[row]);
+}
+
+
+
+/**
+ \brief Scroll the display to bring insertion cursor into view.
+
+ Note: it would be nice to be able to do this without counting lines twice
+ (scroll_() counts them too) and/or to count from the most efficient
+ starting point, but the efficiency of this routine is not as important to
+ the overall performance of the text display.
+ 
+ \todo Unicode?
+ */
+void Fl_Text_Display::display_insert() {
+  int hOffset, topLine, X, Y;
+  hOffset = mHorizOffset;
+  topLine = mTopLineNum;
+  
+  if (insert_position() < mFirstChar) {
+    topLine -= count_lines(insert_position(), mFirstChar, false);
+  } else if (mNVisibleLines>=2 && mLineStarts[mNVisibleLines-2] != -1) {
+    int lastChar = line_end(mLineStarts[mNVisibleLines-2],true);
+    if (insert_position() >= lastChar)
+      topLine += count_lines(lastChar - (wrap_uses_character(mLastChar) ? 0 : 1),
+                             insert_position(), false);
+  }
+  
+  /* Find the new setting for horizontal offset (this is a bit ungraceful).
+   If the line is visible, just use PositionToXY to get the position
+   to scroll to, otherwise, do the vertical scrolling first, then the
+   horizontal */
+  if (!position_to_xy( mCursorPos, &X, &Y )) {
+    scroll_(topLine, hOffset);
+    if (!position_to_xy( mCursorPos, &X, &Y )) {
+#ifdef DEBUG
+      printf ("*** display_insert/position_to_xy # GIVE UP !\n"); fflush(stdout);
+#endif // DEBUG
+      return;   /* Give up, it's not worth it (but why does it fail?) */
+    }
+  }
+  if (X > text_area.x + text_area.w)
+    hOffset += X-(text_area.x + text_area.w);
+  else if (X < text_area.x)
+    hOffset += X-text_area.x;
+  
+  /* Do the scroll */
+  if (topLine != mTopLineNum || hOffset != mHorizOffset)
+    scroll_(topLine, hOffset);
+}
+
+
+/**  
+ \brief Scrolls the text buffer to show the current insert position.
+ This function triggers a complete recalculation, ending in a call to 
+ Fl_Text_Display::display_insert()
+ */
+void Fl_Text_Display::show_insert_position() {
+  display_insert_position_hint = 1;
+  resize(x(), y(), w(), h());
+}
+
+
+/*
+ Cursor movement functions
+ */
+
+/**  
+ \brief Moves the current insert position right one character.
+ \return 1 if the cursor moved, 0 if the end of the text was reached
+ */
+int Fl_Text_Display::move_right() {
+  if ( mCursorPos >= mBuffer->length() )
+    return 0;
+  int p = insert_position();
+  int q = buffer()->next_char(p);
+  insert_position(q);
+  return 1;
+}
+
+
+
+/**  
+ \brief Moves the current insert position left one character.
+ \return 1 if the cursor moved, 0 if the beginning of the text was reached
+ */
+int Fl_Text_Display::move_left() {
+  if ( mCursorPos <= 0 )
+    return 0;
+  int p = insert_position();
+  int q = buffer()->prev_char_clipped(p);
+  insert_position(q);
+  return 1;
+}
+
+
+
+/** 
+ \brief Moves the current insert position up one line.
+ \return 1 if the cursor moved, 0 if the beginning of the text was reached
+ */
+int Fl_Text_Display::move_up() {
+  int lineStartPos, xPos, prevLineStartPos, newPos, visLineNum;
+  
+  /* Find the position of the start of the line.  Use the line starts array
+   if possible */
+  if ( position_to_line( mCursorPos, &visLineNum ) )
+    lineStartPos = mLineStarts[ visLineNum ];
+  else {
+    lineStartPos = line_start( mCursorPos );
+    visLineNum = -1;
+  }
+  if ( lineStartPos == 0 )
+    return 0;
+  
+  /* Decide what column to move to, if there's a preferred column use that */
+  if (mCursorPreferredXPos >= 0)
+    xPos = mCursorPreferredXPos;
+  else
+    xPos = handle_vline(GET_WIDTH, lineStartPos, mCursorPos-lineStartPos, 
+                        0, 0, 0, 0, 0, INT_MAX);
+  
+  /* count forward from the start of the previous line to reach the column */
+  if ( visLineNum != -1 && visLineNum != 0 )
+    prevLineStartPos = mLineStarts[ visLineNum - 1 ];
+  else
+    prevLineStartPos = rewind_lines( lineStartPos, 1 );
+  
+  int lineEnd = line_end(prevLineStartPos, true);
+  newPos = handle_vline(FIND_INDEX_FROM_ZERO, prevLineStartPos, lineEnd-prevLineStartPos, 
+                        0, 0, 0, 0, 0, xPos);
+  
+  /* move the cursor */
+  insert_position( newPos );
+  
+  /* if a preferred column wasn't aleady established, establish it */
+  mCursorPreferredXPos = xPos;
+  return 1;
+}
+
+
+
+/** 
+ \brief Moves the current insert position down one line.
+ \return 1 if the cursor moved, 0 if the beginning of the text was reached
+ */
+int Fl_Text_Display::move_down() {
+  int lineStartPos, xPos, newPos, visLineNum;
+  
+  if ( mCursorPos == mBuffer->length() )
+    return 0;
+  
+  if ( position_to_line( mCursorPos, &visLineNum ) )
+    lineStartPos = mLineStarts[ visLineNum ];
+  else {
+    lineStartPos = line_start( mCursorPos );
+    visLineNum = -1;
+  }
+  if (mCursorPreferredXPos >= 0) {
+    xPos = mCursorPreferredXPos;
+  } else {
+    xPos = handle_vline(GET_WIDTH, lineStartPos, mCursorPos-lineStartPos, 
+                        0, 0, 0, 0, 0, INT_MAX);
+  }
+  
+  int nextLineStartPos = skip_lines( lineStartPos, 1, true );
+  int lineEnd = line_end(nextLineStartPos, true);
+  newPos = handle_vline(FIND_INDEX_FROM_ZERO, nextLineStartPos, lineEnd-nextLineStartPos, 
+                        0, 0, 0, 0, 0, xPos);
+  
+  insert_position( newPos );
+  mCursorPreferredXPos = xPos;
+  return 1;
+}
+
+
+
+/**
+ \brief Count the number of lines between two positions.
+
+ Same as BufCountLines, but takes into account wrapping if wrapping is
+ turned on.  If the caller knows that \p startPos is at a line start, it
+ can pass \p startPosIsLineStart as True to make the call more efficient
+ by avoiding the additional step of scanning back to the last newline.
+
+ \param startPos index to first character
+ \param endPos index after last character
+ \param startPosIsLineStart avoid scanning back to the line start
+ \return number of lines
+ */
+int Fl_Text_Display::count_lines(int startPos, int endPos,
+                                 bool startPosIsLineStart) const {
+  IS_UTF8_ALIGNED2(buffer(), startPos)
+  IS_UTF8_ALIGNED2(buffer(), endPos)
+  
+  int retLines, retPos, retLineStart, retLineEnd;
+  
+#ifdef DEBUG
+  printf("Fl_Text_Display::count_lines(startPos=%d, endPos=%d, startPosIsLineStart=%d\n",
+         startPos, endPos, startPosIsLineStart);
+#endif // DEBUG
+  
+  /* If we're not wrapping use simple (and more efficient) BufCountLines */
+  if (!mContinuousWrap)
+    return buffer()->count_lines(startPos, endPos);
+  
+  wrapped_line_counter(buffer(), startPos, endPos, INT_MAX,
+                       startPosIsLineStart, 0, &retPos, &retLines, &retLineStart,
+                       &retLineEnd);
+  
+#ifdef DEBUG
+  printf("   # after WLC: retPos=%d, retLines=%d, retLineStart=%d, retLineEnd=%d\n",
+         retPos, retLines, retLineStart, retLineEnd);
+#endif // DEBUG
+  
+  return retLines;
+}
+
+
+
+/**
+ \brief Skip a number of lines forward.
+
+ Same as BufCountForwardNLines, but takes into account line breaks when
+ wrapping is turned on. If the caller knows that startPos is at a line start,
+ it can pass "startPosIsLineStart" as True to make the call more efficient
+ by avoiding the additional step of scanning back to the last newline.
+ 
+ \param startPos index to starting character
+ \param nLines number of lines to skip ahead
+ \param startPosIsLineStart avoid scanning back to the line start
+ \return new position as index
+ */
+int Fl_Text_Display::skip_lines(int startPos, int nLines,
+                                bool startPosIsLineStart) {
+  IS_UTF8_ALIGNED2(buffer(), startPos)
+
+  int retLines, retPos, retLineStart, retLineEnd;
+  
+  /* if we're not wrapping use more efficient BufCountForwardNLines */
+  if (!mContinuousWrap)
+    return buffer()->skip_lines(startPos, nLines);
+  
+  /* wrappedLineCounter can't handle the 0 lines case */
+  if (nLines == 0)
+    return startPos;
+  
+  /* use the common line counting routine to count forward */
+  wrapped_line_counter(buffer(), startPos, buffer()->length(),
+                       nLines, startPosIsLineStart, 0, 
+                       &retPos, &retLines, &retLineStart, &retLineEnd);
+  IS_UTF8_ALIGNED2(buffer(), retPos)
+  return retPos;
+}
+
+
+
+/**
+ \brief Returns the end of a line.
+ 
+ Same as BufEndOfLine, but takes into account line breaks when wrapping
+ is turned on.  If the caller knows that \p startPos is at a line start, it
+ can pass "startPosIsLineStart" as True to make the call more efficient
+ by avoiding the additional step of scanning back to the last newline.
+
+ Note that the definition of the end of a line is less clear when continuous
+ wrap is on.  With continuous wrap off, it's just a pointer to the newline
+ that ends the line.  When it's on, it's the character beyond the last
+ \b displayable character on the line, where a whitespace character which has
+ been "converted" to a newline for wrapping is not considered displayable.
+ Also note that a line can be wrapped at a non-whitespace character if the
+ line had no whitespace.  In this case, this routine returns a pointer to
+ the start of the next line.  This is also consistent with the model used by
+ visLineLength.
+ 
+ \param startPos index to starting character
+ \param startPosIsLineStart avoid scanning back to the line start
+ \return new position as index
+ */
+int Fl_Text_Display::line_end(int startPos, bool startPosIsLineStart) const {
+  IS_UTF8_ALIGNED2(buffer(), startPos)
+
+  int retLines, retPos, retLineStart, retLineEnd;
+  
+  /* If we're not wrapping use more efficient BufEndOfLine */
+  if (!mContinuousWrap)
+    return buffer()->line_end(startPos);
+  
+  if (startPos == buffer()->length())
+    return startPos;
+  
+  wrapped_line_counter(buffer(), startPos, buffer()->length(), 1,
+                       startPosIsLineStart, 0, &retPos, &retLines, &retLineStart,
+                       &retLineEnd);
+  
+  IS_UTF8_ALIGNED2(buffer(), retLineEnd)
+  return retLineEnd;
+}
+
+
+
+/**
+ \brief Return the beginning of a line.
+
+ Same as BufStartOfLine, but returns the character after last wrap point
+ rather than the last newline.
+ 
+ \param pos index to starting character
+ \return new position as index
+ */
+int Fl_Text_Display::line_start(int pos) const {
+  IS_UTF8_ALIGNED2(buffer(), pos)
+
+  int retLines, retPos, retLineStart, retLineEnd;
+  
+  /* If we're not wrapping, use the more efficient BufStartOfLine */
+  if (!mContinuousWrap)
+    return buffer()->line_start(pos);
+  
+  wrapped_line_counter(buffer(), buffer()->line_start(pos), pos, INT_MAX, true, 0,
+                       &retPos, &retLines, &retLineStart, &retLineEnd);
+
+  IS_UTF8_ALIGNED2(buffer(), retLineStart)
+  return retLineStart;
+}
+
+
+
+/**
+ \brief Skip a number of lines back.
+
+ Same as BufCountBackwardNLines, but takes into account line breaks when
+ wrapping is turned on.
+
+ \param startPos index to starting character
+ \param nLines number of lines to skip back
+ \return new position as index
+ */
+int Fl_Text_Display::rewind_lines(int startPos, int nLines) {
+  IS_UTF8_ALIGNED2(buffer(), startPos)
+
+  Fl_Text_Buffer *buf = buffer();
+  int pos, lineStart, retLines, retPos, retLineStart, retLineEnd;
+  
+  /* If we're not wrapping, use the more efficient BufCountBackwardNLines */
+  if (!mContinuousWrap)
+    return buf->rewind_lines(startPos, nLines);
+  
+  pos = startPos;
+  for (;;) {
+    lineStart = buf->line_start(pos);
+    wrapped_line_counter(buf, lineStart, pos, INT_MAX, true, 0, 
+                         &retPos, &retLines, &retLineStart, &retLineEnd, false);
+    if (retLines > nLines)
+      return skip_lines(lineStart, retLines-nLines, true);
+    nLines -= retLines;
+    pos = lineStart - 1;
+    if (pos < 0)
+      return 0;
+    nLines -= 1;
+  }
+}
+
+
+
+static inline int fl_isseparator(unsigned int c) {
+  // FIXME: this does not take UCS-4 encoding into account
+  return c != '$' && c != '_' && (isspace(c) || ispunct(c));
+}
+
+
+
+/**   
+ \brief Moves the current insert position right one word.
+ */
+void Fl_Text_Display::next_word() {
+  int pos = insert_position();
+
+  while (pos < buffer()->length() && !fl_isseparator(buffer()->char_at(pos))) {
+    pos = buffer()->next_char(pos);
+  }
+
+  while (pos < buffer()->length() && fl_isseparator(buffer()->char_at(pos))) {
+    pos = buffer()->next_char(pos);
+  }
+  
+  insert_position( pos );
+}
+
+
+
+/**  
+ \brief Moves the current insert position left one word.
+ */
+void Fl_Text_Display::previous_word() {
+  int pos = insert_position();
+  if (pos==0) return;
+  pos = buffer()->prev_char(pos);
+
+  while (pos && fl_isseparator(buffer()->char_at(pos))) {
+    pos = buffer()->prev_char(pos);
+  }
+
+  while (pos && !fl_isseparator(buffer()->char_at(pos))) {
+    pos = buffer()->prev_char(pos);
+  }
+
+  if (fl_isseparator(buffer()->char_at(pos))) {
+    pos = buffer()->next_char(pos);
+  }
+  
+  insert_position( pos );
+}
+
+
+
+/**
+ \brief This is called before any characters are deleted.
+ 
+ Callback attached to the text buffer to receive delete information before
+ the modifications are actually made.
+ 
+ \param pos starting index of deletion
+ \param nDeleted number of bytes we will delete (must be UTF-8 aligned!)
+ \param cbArg "this" pointer for static callback function
+ */
+void Fl_Text_Display::buffer_predelete_cb(int pos, int nDeleted, void *cbArg) {
+  Fl_Text_Display *textD = (Fl_Text_Display *)cbArg;
+  if (textD->mContinuousWrap) {
+  /* Note: we must perform this measurement, even if there is not a
+   single character deleted; the number of "deleted" lines is the
+   number of visual lines spanned by the real line in which the
+   modification takes place.
+   Also, a modification of the tab distance requires the same
+   kind of calculations in advance, even if the font width is "fixed",
+   because when the width of the tab characters changes, the layout
+   of the text may be completely different. */
+    IS_UTF8_ALIGNED2(textD->buffer(), pos)
+    textD->measure_deleted_lines(pos, nDeleted);
+  } else {
+    textD->mSuppressResync = 0; /* Probably not needed, but just in case */
+  }
+}
+
+
+
+/**
+ \brief This is called whenever the buffer is modified.
+ 
+ Callback attached to the text buffer to receive modification information
+
+ \param pos starting index of modification
+ \param nInserted number of bytes we inserted (must be UTF-8 aligned!)
+ \param nDeleted number of bytes deleted (must be UTF-8 aligned!)
+ \param nRestyled ??
+ \param deletedText this is what was removed, must not be NULL if nDeleted is set
+ \param cbArg "this" pointer for static callback function
+ */
+void Fl_Text_Display::buffer_modified_cb( int pos, int nInserted, int nDeleted,
+                                         int nRestyled, const char *deletedText, void *cbArg ) {
+  int linesInserted, linesDeleted, startDispPos, endDispPos;
+  Fl_Text_Display *textD = ( Fl_Text_Display * ) cbArg;
+  Fl_Text_Buffer *buf = textD->mBuffer;
+  int oldFirstChar = textD->mFirstChar;
+  int scrolled, origCursorPos = textD->mCursorPos;
+  int wrapModStart = 0, wrapModEnd = 0;
+
+  IS_UTF8_ALIGNED2(buf, pos)
+  IS_UTF8_ALIGNED2(buf, oldFirstChar)
+  
+  /* buffer modification cancels vertical cursor motion column */
+  if ( nInserted != 0 || nDeleted != 0 )
+    textD->mCursorPreferredXPos = -1;
+  
+  /* Count the number of lines inserted and deleted, and in the case
+   of continuous wrap mode, how much has changed */
+  if (textD->mContinuousWrap) {
+    textD->find_wrap_range(deletedText, pos, nInserted, nDeleted,
+                           &wrapModStart, &wrapModEnd, &linesInserted, &linesDeleted);
+  } else {
+    linesInserted = nInserted == 0 ? 0 : buf->count_lines( pos, pos + nInserted );
+    linesDeleted = nDeleted == 0 ? 0 : countlines( deletedText );
+  }
+  
+  /* Update the line starts and mTopLineNum */
+  if ( nInserted != 0 || nDeleted != 0 ) {
+    if (textD->mContinuousWrap) {
+      textD->update_line_starts( wrapModStart, wrapModEnd-wrapModStart,
+                                nDeleted + pos-wrapModStart + (wrapModEnd-(pos+nInserted)),
+                                linesInserted, linesDeleted, &scrolled );
+    } else {
+      textD->update_line_starts( pos, nInserted, nDeleted, linesInserted,
+                                linesDeleted, &scrolled );
+    }
+  } else
+    scrolled = 0;
+  
+  /* If we're counting non-wrapped lines as well, maintain the absolute
+   (non-wrapped) line number of the text displayed */
+  if (textD->maintaining_absolute_top_line_number() &&
+      (nInserted != 0 || nDeleted != 0)) {
+    if (deletedText && (pos + nDeleted < oldFirstChar))
+      textD->mAbsTopLineNum += buf->count_lines(pos, pos + nInserted) -
+                               countlines(deletedText);
+    else if (pos < oldFirstChar)
+      textD->reset_absolute_top_line_number();
+  }    	    
+  
+  /* Update the line count for the whole buffer */
+  textD->mNBufferLines += linesInserted - linesDeleted;
+  
+  /* Update the cursor position */
+  if ( textD->mCursorToHint != NO_HINT ) {
+    textD->mCursorPos = textD->mCursorToHint;
+    textD->mCursorToHint = NO_HINT;
+  } else if ( textD->mCursorPos > pos ) {
+    if ( textD->mCursorPos < pos + nDeleted )
+      textD->mCursorPos = pos;
+    else
+      textD->mCursorPos += nInserted - nDeleted;
+  }
+  
+  // refigure scrollbars & stuff
+  textD->resize(textD->x(), textD->y(), textD->w(), textD->h());
+  
+  // don't need to do anything else if not visible?
+  if (!textD->visible_r()) return;
+  
+  /* If the changes caused scrolling, re-paint everything and we're done. */
+  if ( scrolled ) {
+    textD->damage(FL_DAMAGE_EXPOSE);
+    if ( textD->mStyleBuffer )   /* See comments in extendRangeForStyleMods */
+      textD->mStyleBuffer->primary_selection()->selected(0);
+    return;
+  }
+  
+  /* If the changes didn't cause scrolling, decide the range of characters
+   that need to be re-painted.  Also if the cursor position moved, be
+   sure that the redisplay range covers the old cursor position so the
+   old cursor gets erased, and erase the bits of the cursor which extend
+   beyond the left and right edges of the text. */
+  startDispPos = textD->mContinuousWrap ? wrapModStart : pos;
+  IS_UTF8_ALIGNED2(buf, startDispPos)
+  
+  if ( origCursorPos == startDispPos && textD->mCursorPos != startDispPos )
+    startDispPos = min( startDispPos, buf->prev_char_clipped(origCursorPos) );
+  IS_UTF8_ALIGNED2(buf, startDispPos)
+  
+  if ( linesInserted == linesDeleted ) {
+    if ( nInserted == 0 && nDeleted == 0 )
+      endDispPos = pos + nRestyled;
+    else {
+      if (textD->mContinuousWrap)
+        endDispPos = wrapModEnd;
+      else
+        endDispPos = buf->next_char(buf->line_end( pos + nInserted ));
+      
+      // CET - FIXME      if ( origCursorPos >= startDispPos &&
+      //                ( origCursorPos <= endDispPos || endDispPos == buf->length() ) )
+    }
+    
+    if (linesInserted > 1) textD->draw_line_numbers(false);
+  } else {
+    endDispPos = buf->next_char(textD->mLastChar);
+    // CET - FIXME   if ( origCursorPos >= pos )
+    /* If more than one line is inserted/deleted, a line break may have
+     been inserted or removed in between, and the line numbers may
+     have changed. If only one line is altered, line numbers cannot
+     be affected (the insertion or removal of a line break always 
+     results in at least two lines being redrawn). */
+    textD->draw_line_numbers(false);
+  }
+  IS_UTF8_ALIGNED2(buf, startDispPos)
+  IS_UTF8_ALIGNED2(buf, endDispPos)
+  
+  /* If there is a style buffer, check if the modification caused additional
+   changes that need to be redisplayed.  (Redisplaying separately would
+   cause double-redraw on almost every modification involving styled
+   text).  Extend the redraw range to incorporate style changes */
+  if ( textD->mStyleBuffer )
+    textD->extend_range_for_styles( &startDispPos, &endDispPos );
+  IS_UTF8_ALIGNED2(buf, startDispPos)
+  IS_UTF8_ALIGNED2(buf, endDispPos)
+  
+  /* Redisplay computed range */
+  textD->redisplay_range( startDispPos, endDispPos );
+}
+
+
+
+/**
+ \brief Line numbering stuff, currently unused.
+ 
+ In continuous wrap mode, internal line numbers are calculated after
+ wrapping.  A separate non-wrapped line count is maintained when line
+ numbering is turned on.  There is some performance cost to maintaining this
+ line count, so normally absolute line numbers are not tracked if line
+ numbering is off.  This routine allows callers to specify that they still
+ want this line count maintained (for use via TextDPosToLineAndCol).
+ More specifically, this allows the line number reported in the statistics
+ line to be calibrated in absolute lines, rather than post-wrapped lines.
+ */
+void Fl_Text_Display::maintain_absolute_top_line_number(int state) {
+  mNeedAbsTopLineNum = state;
+  reset_absolute_top_line_number();
+}
+
+
+
+/**
+ \brief Line numbering stuff, currently unused.
+ 
+ Returns the absolute (non-wrapped) line number of the first line displayed.
+ Returns 0 if the absolute top line number is not being maintained.
+ */
+int Fl_Text_Display::get_absolute_top_line_number() const {
+  if (!mContinuousWrap)
+    return mTopLineNum;
+  if (maintaining_absolute_top_line_number())
+    return mAbsTopLineNum;
+  return 0;
+}
+
+
+
+/**
+ \brief Line numbering stuff, currently unused.
+ 
+ Re-calculate absolute top line number for a change in scroll position.
+ */
+void Fl_Text_Display::absolute_top_line_number(int oldFirstChar) {
+  if (maintaining_absolute_top_line_number()) {
+    if (mFirstChar < oldFirstChar)
+      mAbsTopLineNum -= buffer()->count_lines(mFirstChar, oldFirstChar);
+    else
+      mAbsTopLineNum += buffer()->count_lines(oldFirstChar, mFirstChar);
+  }
+}
+
+
+
+/**
+ \brief Line numbering stuff, currently unused.
+ 
+ Return true if a separate absolute top line number is being maintained
+ (for displaying line numbers or showing in the statistics line).
+ */
+int Fl_Text_Display::maintaining_absolute_top_line_number() const {
+  return mContinuousWrap &&
+  (mLineNumWidth != 0 || mNeedAbsTopLineNum);
+}
+
+
+
+/**
+ \brief Line numbering stuff, probably unused.
+ 
+ Count lines from the beginning of the buffer to reestablish the
+ absolute (non-wrapped) top line number.  If mode is not continuous wrap,
+ or the number is not being maintained, does nothing.
+ */
+void Fl_Text_Display::reset_absolute_top_line_number() {
+  mAbsTopLineNum = 1;
+  absolute_top_line_number(0);
+}
+
+
+
+/**
+ \brief Convert a position index into a line number offset.
+ 
+ Find the line number of position \p pos relative to the first line of
+ displayed text. Returns 0 if the line is not displayed.
+ 
+ \param pos ??
+ \param[out] lineNum ??
+ \return ??
+ \todo What does this do?
+ */
+int Fl_Text_Display::position_to_line( int pos, int *lineNum ) const {
+  IS_UTF8_ALIGNED2(buffer(), pos)
+
+  int i;
+  
+  *lineNum = 0;
+  if ( pos < mFirstChar ) return 0;
+  if ( pos > mLastChar ) {
+    if ( empty_vlines() ) {
+      if ( mLastChar < mBuffer->length() ) {
+        if ( !position_to_line( mLastChar, lineNum ) ) {
+          Fl::error("Fl_Text_Display::position_to_line(): Consistency check ptvl failed");
+          return 0;
+        }
+        return ++( *lineNum ) <= mNVisibleLines - 1;
+      } else {
+        position_to_line( buffer()->prev_char_clipped(mLastChar), lineNum );
+        return 1;
+      }
+    }
+    return 0;
+  }
+  
+  for ( i = mNVisibleLines - 1; i >= 0; i-- ) {
+    if ( mLineStarts[ i ] != -1 && pos >= mLineStarts[ i ] ) {
+      *lineNum = i;
+      return 1;
+    }
+  }
+  return 0;   /* probably never be reached */
+}
+
+
+/**
+ Universal pixel machine.
+
+ We use a single function that handles all line layout, measuring, and drawing
+  \li draw a text range
+  \li return the width of a text range in pixels
+  \li return the index of a character that is at a pixel position
+
+ \param[in] mode DRAW_LINE, GET_WIDTH, FIND_INDEX
+ \param[in] lineStartPos index of first character
+ \param[in] lineLen size of string in bytes
+ \param[in] leftChar, rightChar
+ \param[in] Y drawing position
+ \param[in] bottomClip, leftClip, rightClip stop work when we reach the clipped 
+            area. rightClip is the X position that we search in FIND_INDEX.
+ \retval DRAW_LINE index of last drawn character
+ \retval GET_WIDTH width in pixels of text segment if we would draw it
+ \retval FIND_INDEX index of character at given x position in window coordinates
+ \retval FIND_INDEX_FROM_ZERO index of character at given x position without scrolling and widget offsets
+ \todo we need to handle hidden hyphens and tabs here!
+ \todo we handle all styles and selections 
+ \todo we must provide code to get pixel positions of the middle of a character as well
+ */
+int Fl_Text_Display::handle_vline(
+                                  int mode, 
+                                  int lineStartPos, int lineLen, int leftChar, int rightChar,
+                                  int Y, int bottomClip,
+                                  int leftClip, int rightClip) const
+{
+  IS_UTF8_ALIGNED2(buffer(), lineStartPos)
+
+  // FIXME: we need to allow two modes for FIND_INDEX: one on the edge of the 
+  // FIXME: character for selection, and one on the character center for cursors.
+  int i, X, startX, startIndex, style, charStyle;
+  char *lineStr;
+  
+  if ( lineStartPos == -1 ) {
+    lineStr = NULL;
+  } else {
+    lineStr = mBuffer->text_range( lineStartPos, lineStartPos + lineLen );
+  }
+  
+  if (mode==GET_WIDTH) {
+    X = 0;
+  } else if (mode==FIND_INDEX_FROM_ZERO) {
+    X = 0; 
+    mode = FIND_INDEX;
+  } else {
+    X = text_area.x - mHorizOffset;
+  }
+  
+  startX = X;
+  startIndex = 0;
+  if (!lineStr) {
+    // just clear the background
+    if (mode==DRAW_LINE) {
+      style = position_style(lineStartPos, lineLen, -1);
+      draw_string( style|BG_ONLY_MASK, text_area.x, Y, text_area.x+text_area.w, lineStr, lineLen );
+    }
+    if (mode==FIND_INDEX) {
+      IS_UTF8_ALIGNED2(buffer(), lineStartPos)
+      return lineStartPos;
+    }
+    return 0;
+  }
+  
+  char currChar = 0, prevChar = 0;
+  // draw the line
+  style = position_style(lineStartPos, lineLen, 0);
+  for (i=0; i<lineLen; ) {
+    currChar = lineStr[i]; // one byte is enough to handele tabs and other cases
+    int len = fl_utf8len1(currChar);
+    if (len<=0) len = 1; // OUCH!
+    charStyle = position_style(lineStartPos, lineLen, i);
+    if (charStyle!=style || currChar=='\t' || prevChar=='\t') {
+      // draw a segment whenever the style changes or a Tab is found
+      int w = 0;
+      if (prevChar=='\t') {
+        // draw a single Tab space
+        int tab = (int)col_to_x(mBuffer->tab_distance());
+        int xAbs = (mode==GET_WIDTH) ? startX : startX+mHorizOffset-text_area.x;
+        w = (((xAbs/tab)+1)*tab) - xAbs;
+        if (mode==DRAW_LINE)
+          draw_string( style|BG_ONLY_MASK, startX, Y, startX+w, 0, 0 );
+        if (mode==FIND_INDEX && startX+w>rightClip) {
+          // find x pos inside block
+          free(lineStr);
+          return lineStartPos + startIndex;
+        }
+      } else {
+        // draw a text segment
+        w = int( string_width( lineStr+startIndex, i-startIndex, style ) );
+        if (mode==DRAW_LINE)
+          draw_string( style, startX, Y, startX+w, lineStr+startIndex, i-startIndex );
+        if (mode==FIND_INDEX && startX+w>rightClip) {
+          // find x pos inside block
+          int di = find_x(lineStr+startIndex, i-startIndex, style, rightClip-startX);
+          free(lineStr);
+          IS_UTF8_ALIGNED2(buffer(), (lineStartPos+startIndex+di))
+          return lineStartPos + startIndex + di;
+        }
+      }
+      style = charStyle;
+      startX += w;
+      startIndex = i;
+    }
+    i += len;
+    prevChar = currChar;
+  }
+  int w = 0;
+  if (currChar=='\t') {
+    // draw a single Tab space
+    int tab = (int)col_to_x(mBuffer->tab_distance());
+    int xAbs = (mode==GET_WIDTH) ? startX : startX+mHorizOffset-text_area.x;
+    w = (((xAbs/tab)+1)*tab) - xAbs;
+    if (mode==DRAW_LINE)
+      draw_string( style|BG_ONLY_MASK, startX, Y, startX+w, 0, 0 );
+    if (mode==FIND_INDEX) {
+      // find x pos inside block
+      free(lineStr);
+      return lineStartPos + startIndex + ( rightClip-startX>w ? 1 : 0 );
+    }
+  } else {
+    w = int( string_width( lineStr+startIndex, i-startIndex, style ) );
+    if (mode==DRAW_LINE)
+      draw_string( style, startX, Y, startX+w, lineStr+startIndex, i-startIndex );
+    if (mode==FIND_INDEX) {
+      // find x pos inside block
+      int di = find_x(lineStr+startIndex, i-startIndex, style, rightClip-startX);
+      free(lineStr);
+      IS_UTF8_ALIGNED2(buffer(), (lineStartPos+startIndex+di))
+      return lineStartPos + startIndex + di;
+    }
+  }
+  if (mode==GET_WIDTH) {
+    free(lineStr);
+    return startX+w;
+  }
+  
+  // clear the rest of the line
+  startX += w;
+  style = position_style(lineStartPos, lineLen, i);
+  if (mode==DRAW_LINE)
+    draw_string( style|BG_ONLY_MASK, startX, Y, text_area.x+text_area.w, lineStr, lineLen );
+  
+  free(lineStr);
+  IS_UTF8_ALIGNED2(buffer(), (lineStartPos+lineLen))
+  return lineStartPos + lineLen;
+}
+
+
+/**
+ \brief Find the index of the character that lies at the given x position.
+ \param s UTF-8 text string
+ \param len length of string
+ \param style index into style lookup table
+ \param x position in pixels
+ \return index into buffer
+ */
+int Fl_Text_Display::find_x(const char *s, int len, int style, int x) const {
+  IS_UTF8_ALIGNED(s)
+
+  // TODO: use binary search which may be quicker.
+  int i = 0;
+  while (i<len) {
+    int cl = fl_utf8len1(s[i]);
+    int w = int( string_width(s, i+cl, style) );
+    if (w>x) 
+      return i;
+    i += cl;
+  }  
+  return len;
+}
+
+
+
+/**
+ \brief Draw a single line of text.
+ 
+ Draw the text on a single line represented by \p visLineNum (the
+ number of lines down from the top of the display), limited by
+ \p leftClip and \p rightClip window coordinates and \p leftCharIndex and
+ \p rightCharIndex character positions (not including the character at
+ position \p rightCharIndex).
+ 
+ \param visLineNum index of line in the visible line number lookup
+ \param leftClip, rightClip pixel position of clipped area
+ \param leftCharIndex, rightCharIndex index into line of segment that we want to draw
+ */
+void Fl_Text_Display::draw_vline(int visLineNum, int leftClip, int rightClip,
+                                 int leftCharIndex, int rightCharIndex) {
+  int Y, lineStartPos, lineLen, fontHeight;
+  
+  //  printf("draw_vline(visLineNum=%d, leftClip=%d, rightClip=%d, leftCharIndex=%d, rightCharIndex=%d)\n",
+  //         visLineNum, leftClip, rightClip, leftCharIndex, rightCharIndex);
+  //  printf("nNVisibleLines=%d\n", mNVisibleLines);
+  
+  /* If line is not displayed, skip it */
+  if ( visLineNum < 0 || visLineNum >= mNVisibleLines )
+    return;
+  
+  /* Calculate Y coordinate of the string to draw */
+  fontHeight = mMaxsize;
+  Y = text_area.y + visLineNum * fontHeight;
+  
+  /* Get the text, length, and  buffer position of the line to display */
+  lineStartPos = mLineStarts[ visLineNum ];
+  if ( lineStartPos == -1 ) {
+    lineLen = 0;
+  } else {
+    lineLen = vline_length( visLineNum );
+  }
+  
+  /* Shrink the clipping range to the active display area */
+  leftClip = max( text_area.x, leftClip );
+  rightClip = min( rightClip, text_area.x + text_area.w );
+  
+  handle_vline(DRAW_LINE, 
+               lineStartPos, lineLen, leftCharIndex, rightCharIndex,
+               Y, Y+fontHeight, leftClip, rightClip);
+  return;
+}
+
+
+
+/**
+ \brief Draw a text segment in a single style.
+ 
+ Draw a string or blank area according to parameter \p style, using the
+ appropriate colors and drawing method for that style, with top left
+ corner at \p X, \p Y.  If style says to draw text, use \p string as
+ source of characters, and draw \p nChars, if style is FILL, erase
+ rectangle where text would have drawn from \p X to \p toX and from
+ \p Y to the maximum y extent of the current font(s).
+ 
+ \param style index into style lookup table
+ \param X, Y drawing origin
+ \param toX rightmost position if this is a fill operation
+ \param string text if this is a drawing operation
+ \param nChars number of characters to draw
+ */
+void Fl_Text_Display::draw_string(int style, 
+                                  int X, int Y, int toX,
+                                  const char *string, int nChars) const {
+  IS_UTF8_ALIGNED(string)
+
+  const Style_Table_Entry * styleRec;
+  
+  /* Draw blank area rather than text, if that was the request */
+  if ( style & FILL_MASK ) {
+    if (style & TEXT_ONLY_MASK) return;
+    clear_rect( style, X, Y, toX - X, mMaxsize );
+    return;
+  }
+  /* Set font, color, and gc depending on style.  For normal text, GCs
+   for normal drawing, or drawing within a Fl_Text_Selection or highlight are
+   pre-allocated and pre-configured.  For syntax highlighting, GCs are
+   configured here, on the fly. */
+  
+  Fl_Font font = textfont();
+  int fsize = textsize();
+  Fl_Color foreground;
+  Fl_Color background;
+  
+  if ( style & STYLE_LOOKUP_MASK ) {
+    int si = (style & STYLE_LOOKUP_MASK) - 'A';
+    if (si < 0) si = 0;
+    else if (si >= mNStyles) si = mNStyles - 1;
+    
+    styleRec = mStyleTable + si;
+    font  = styleRec->font;
+    fsize = styleRec->size;
+    
+    if (style & PRIMARY_MASK) {
+      if (Fl::focus() == (Fl_Widget*)this) background = selection_color();
+      else background = fl_color_average(color(), selection_color(), 0.4f);
+    } else if (style & HIGHLIGHT_MASK) {
+      if (Fl::focus() == (Fl_Widget*)this) background = fl_color_average(color(), selection_color(), 0.5f);
+      else background = fl_color_average(color(), selection_color(), 0.6f);
+    } else background = color();
+    foreground = fl_contrast(styleRec->color, background);
+  } else if (style & PRIMARY_MASK) {
+    if (Fl::focus() == (Fl_Widget*)this) background = selection_color();
+    else background = fl_color_average(color(), selection_color(), 0.4f);
+    foreground = fl_contrast(textcolor(), background);
+  } else if (style & HIGHLIGHT_MASK) {
+    if (Fl::focus() == (Fl_Widget*)this) background = fl_color_average(color(), selection_color(), 0.5f);
+    else background = fl_color_average(color(), selection_color(), 0.6f);
+    foreground = fl_contrast(textcolor(), background);
+  } else {
+    foreground = textcolor();
+    background = color();
+  }
+  
+  if (!(style & TEXT_ONLY_MASK)) {
+    fl_color( background );
+    fl_rectf( X, Y, toX - X, mMaxsize );
+  }
+  if (!(style & BG_ONLY_MASK)) {
+    fl_color( foreground );
+    fl_font( font, fsize );
+#if !(defined(__APPLE__) || defined(WIN32)) && USE_XFT
+    // makes sure antialiased ÄÖÜ do not leak on line above
+    fl_push_clip(X, Y, toX - X, mMaxsize);
+#endif
+    fl_draw( string, nChars, X, Y + mMaxsize - fl_descent());
+#if !(defined(__APPLE__) || defined(WIN32)) && USE_XFT
+    fl_pop_clip();
+#endif
+  }
+  
+  // CET - FIXME
+  /* If any space around the character remains unfilled (due to use of
+   different sized fonts for highlighting), fill in above or below
+   to erase previously drawn characters */
+  /*
+   if (fs->ascent < mAscent)
+   clear_rect( style, X, Y, toX - X, mAscent - fs->ascent);
+   if (fs->descent < mDescent)
+   clear_rect( style, X, Y + mAscent + fs->descent, toX - x,
+   mDescent - fs->descent);
+   */
+  /* Underline if style is secondary Fl_Text_Selection */
+  
+  /*
+   if (style & SECONDARY_MASK)
+   XDrawLine(XtDisplay(mW), XtWindow(mW), gc, x,
+   y + mAscent, toX - 1, Y + fs->ascent);
+   */
+}
+
+
+
+/**
+ \brief Clear a rectangle with the appropriate background color for \p style.
+ 
+ \param style index into style table
+ \param X, Y, width, height size and position of background area
+ */
+void Fl_Text_Display::clear_rect(int style, 
+                                 int X, int Y,
+                                 int width, int height) const {
+  /* A width of zero means "clear to end of window" to XClearArea */
+  if ( width == 0 )
+    return;
+  
+  if (style & PRIMARY_MASK) {
+    if (Fl::focus()==(Fl_Widget*)this) {
+      fl_color(selection_color());
+    } else {
+      fl_color(fl_color_average(color(), selection_color(), 0.4f));
+    }
+  } else if (style & HIGHLIGHT_MASK) {
+    if (Fl::focus()==(Fl_Widget*)this) {
+      fl_color(fl_color_average(color(), selection_color(), 0.5f));
+    } else {
+      fl_color(fl_color_average(color(), selection_color(), 0.6f));
+    }
+  } else {
+    fl_color( color() );
+  }
+  fl_rectf( X, Y, width, height );
+}
+
+
+
+/**
+ \brief Draw a cursor with top center at \p X, \p Y.
+ 
+ \param X, Y cursor position in pixels
+ */
+void Fl_Text_Display::draw_cursor( int X, int Y ) {
+
+  typedef struct {
+    int x1, y1, x2, y2;
+  }
+  Segment;
+
+  Segment segs[ 5 ];
+  int left, right, cursorWidth, midY;
+  //    int fontWidth = mFontStruct->min_bounds.width, nSegs = 0;
+  int fontWidth = TMPFONTWIDTH; // CET - FIXME
+  int nSegs = 0;
+  int fontHeight = mMaxsize;
+  int bot = Y + fontHeight - 1;
+  
+  if ( X < text_area.x - 1 || X > text_area.x + text_area.w )
+    return;
+  
+  /* For cursors other than the block, make them around 2/3 of a character
+   width, rounded to an even number of pixels so that X will draw an
+   odd number centered on the stem at x. */
+  cursorWidth = 4;   //(fontWidth/3) * 2;
+  left = X - cursorWidth / 2;
+  right = left + cursorWidth;
+  
+  /* Create segments and draw cursor */
+  if ( mCursorStyle == CARET_CURSOR ) {
+    midY = bot - fontHeight / 5;
+    segs[ 0 ].x1 = left; segs[ 0 ].y1 = bot; segs[ 0 ].x2 = X; segs[ 0 ].y2 = midY;
+    segs[ 1 ].x1 = X; segs[ 1 ].y1 = midY; segs[ 1 ].x2 = right; segs[ 1 ].y2 = bot;
+    segs[ 2 ].x1 = left; segs[ 2 ].y1 = bot; segs[ 2 ].x2 = X; segs[ 2 ].y2 = midY - 1;
+    segs[ 3 ].x1 = X; segs[ 3 ].y1 = midY - 1; segs[ 3 ].x2 = right; segs[ 3 ].y2 = bot;
+    nSegs = 4;
+  } else if ( mCursorStyle == NORMAL_CURSOR ) {
+    segs[ 0 ].x1 = left; segs[ 0 ].y1 = Y; segs[ 0 ].x2 = right; segs[ 0 ].y2 = Y;
+    segs[ 1 ].x1 = X; segs[ 1 ].y1 = Y; segs[ 1 ].x2 = X; segs[ 1 ].y2 = bot;
+    segs[ 2 ].x1 = left; segs[ 2 ].y1 = bot; segs[ 2 ].x2 = right; segs[ 2 ].y2 = bot;
+    nSegs = 3;
+  } else if ( mCursorStyle == HEAVY_CURSOR ) {
+    segs[ 0 ].x1 = X - 1; segs[ 0 ].y1 = Y; segs[ 0 ].x2 = X - 1; segs[ 0 ].y2 = bot;
+    segs[ 1 ].x1 = X; segs[ 1 ].y1 = Y; segs[ 1 ].x2 = X; segs[ 1 ].y2 = bot;
+    segs[ 2 ].x1 = X + 1; segs[ 2 ].y1 = Y; segs[ 2 ].x2 = X + 1; segs[ 2 ].y2 = bot;
+    segs[ 3 ].x1 = left; segs[ 3 ].y1 = Y; segs[ 3 ].x2 = right; segs[ 3 ].y2 = Y;
+    segs[ 4 ].x1 = left; segs[ 4 ].y1 = bot; segs[ 4 ].x2 = right; segs[ 4 ].y2 = bot;
+    nSegs = 5;
+  } else if ( mCursorStyle == DIM_CURSOR ) {
+    midY = Y + fontHeight / 2;
+    segs[ 0 ].x1 = X; segs[ 0 ].y1 = Y; segs[ 0 ].x2 = X; segs[ 0 ].y2 = Y;
+    segs[ 1 ].x1 = X; segs[ 1 ].y1 = midY; segs[ 1 ].x2 = X; segs[ 1 ].y2 = midY;
+    segs[ 2 ].x1 = X; segs[ 2 ].y1 = bot; segs[ 2 ].x2 = X; segs[ 2 ].y2 = bot;
+    nSegs = 3;
+  } else if ( mCursorStyle == BLOCK_CURSOR ) {
+    right = X + fontWidth;
+    segs[ 0 ].x1 = X; segs[ 0 ].y1 = Y; segs[ 0 ].x2 = right; segs[ 0 ].y2 = Y;
+    segs[ 1 ].x1 = right; segs[ 1 ].y1 = Y; segs[ 1 ].x2 = right; segs[ 1 ].y2 = bot;
+    segs[ 2 ].x1 = right; segs[ 2 ].y1 = bot; segs[ 2 ].x2 = X; segs[ 2 ].y2 = bot;
+    segs[ 3 ].x1 = X; segs[ 3 ].y1 = bot; segs[ 3 ].x2 = X; segs[ 3 ].y2 = Y;
+    nSegs = 4;
+  }
+  fl_color( mCursor_color );
+  
+  for ( int k = 0; k < nSegs; k++ ) {
+    fl_line( segs[ k ].x1, segs[ k ].y1, segs[ k ].x2, segs[ k ].y2 );
+  }
+}
+
+
+
+/**
+ \brief Find the correct style for a character.
+
+ Determine the drawing method to use to draw a specific character from "buf".
+ \p lineStartPos gives the character index where the line begins, \p lineIndex,
+ the number of characters past the beginning of the line, and \p lineIndex
+ the number of displayed characters past the beginning of the line.  Passing
+ \p lineStartPos of -1 returns the drawing style for "no text".
+
+ Why not just: position_style(pos)?  Because style applies to blank areas
+ of the window beyond the text boundaries, and because this routine must also
+ decide whether a position is inside of a rectangular Fl_Text_Selection, and do
+ so efficiently, without re-counting character positions from the start of the
+ line.
+
+ Note that style is a somewhat incorrect name, drawing method would
+ be more appropriate.
+
+ \param lineStartPos beginning of this line
+ \param lineLen number of bytes in line
+ \param lineIndex position of character within line
+ \return style for the given character
+ */
+int Fl_Text_Display::position_style( int lineStartPos, int lineLen, int lineIndex) const 
+{
+  IS_UTF8_ALIGNED2(buffer(), lineStartPos)
+
+  Fl_Text_Buffer * buf = mBuffer;
+  Fl_Text_Buffer *styleBuf = mStyleBuffer;
+  int pos, style = 0;
+  
+  if ( lineStartPos == -1 || buf == NULL )
+    return FILL_MASK;
+  
+  pos = lineStartPos + min( lineIndex, lineLen );
+  
+  if ( lineIndex >= lineLen )
+    style = FILL_MASK;
+  else if ( styleBuf != NULL ) {
+    style = ( unsigned char ) styleBuf->byte_at( pos );
+    if (style == mUnfinishedStyle && mUnfinishedHighlightCB) {
+      /* encountered "unfinished" style, trigger parsing */
+      (mUnfinishedHighlightCB)( pos, mHighlightCBArg);
+      style = (unsigned char) styleBuf->byte_at( pos);
+    }
+  }
+  if (buf->primary_selection()->includes(pos))
+    style |= PRIMARY_MASK;
+  if (buf->highlight_selection()->includes(pos))
+    style |= HIGHLIGHT_MASK;
+  if (buf->secondary_selection()->includes(pos))
+    style |= SECONDARY_MASK;
+  return style;
+}
+
+
+/**
+ \brief Find the width of a string in the font of a particular style.
+ 
+ \param string the text
+ \param length number of bytes in string
+ \param style index into style table
+ \return width of text segment in pixels
+ */
+double Fl_Text_Display::string_width( const char *string, int length, int style ) const {
+  IS_UTF8_ALIGNED(string)
+
+  Fl_Font font;
+  Fl_Fontsize fsize;
+  
+  if ( mNStyles && (style & STYLE_LOOKUP_MASK) ) {
+    int si = (style & STYLE_LOOKUP_MASK) - 'A';
+    if (si < 0) si = 0;
+    else if (si >= mNStyles) si = mNStyles - 1;
+    
+    font  = mStyleTable[si].font;
+    fsize = mStyleTable[si].size;
+  } else {
+    font  = textfont();
+    fsize = textsize();
+  }
+  fl_font( font, fsize );
+  return fl_width( string, length );
+}
+
+
+
+/**
+ \brief Translate a pixel position into a character index.
+
+ Translate window coordinates to the nearest (insert cursor or character
+ cell) text position.  The parameter \p posType specifies how to interpret the
+ position: CURSOR_POS means translate the coordinates to the nearest cursor
+ position, and CHARACTER_POS means return the position of the character
+ closest to (\p X, \p Y).
+
+ \param X, Y pixel position
+ \param posType CURSOR_POS or CHARACTER_POS
+ \return index into text buffer
+ */
+int Fl_Text_Display::xy_to_position( int X, int Y, int posType ) const {
+  int lineStart, lineLen, fontHeight;
+  int visLineNum;
+  
+  /* Find the visible line number corresponding to the Y coordinate */
+  fontHeight = mMaxsize;
+  visLineNum = ( Y - text_area.y ) / fontHeight;
+  if ( visLineNum < 0 )
+    return mFirstChar;
+  if ( visLineNum >= mNVisibleLines )
+    visLineNum = mNVisibleLines - 1;
+  
+  /* Find the position at the start of the line */
+  lineStart = mLineStarts[ visLineNum ];
+  
+  /* If the line start was empty, return the last position in the buffer */
+  if ( lineStart == -1 )
+    return mBuffer->length();
+  
+  /* Get the line text and its length */
+  lineLen = vline_length( visLineNum );
+  
+  return handle_vline(FIND_INDEX, 
+                      lineStart, lineLen, 0, 0, 
+                      0, 0,
+                      text_area.x, X);
+}
+
+
+
+/**
+ \brief Translate pixel coordinates into row and column.
+ 
+ Translate window coordinates to the nearest row and column number for
+ positioning the cursor.  This, of course, makes no sense when the font is
+ proportional, since there are no absolute columns.  The parameter posType
+ specifies how to interpret the position: CURSOR_POS means translate the
+ coordinates to the nearest position between characters, and CHARACTER_POS
+ means translate the position to the nearest character cell.
+ 
+ \param X, Y pixel coordinates
+ \param[out] row, column neares row and column
+ \param posType CURSOR_POS or CHARACTER_POS
+ */
+void Fl_Text_Display::xy_to_rowcol( int X, int Y, int *row,
+                                   int *column, int posType ) const {
+  int fontHeight = mMaxsize;
+  int fontWidth = TMPFONTWIDTH;   //mFontStruct->max_bounds.width;
+  
+  /* Find the visible line number corresponding to the Y coordinate */
+  *row = ( Y - text_area.y ) / fontHeight;
+  if ( *row < 0 ) *row = 0;
+  if ( *row >= mNVisibleLines ) *row = mNVisibleLines - 1;
+  
+  *column = ( ( X - text_area.x ) + mHorizOffset +
+             ( posType == CURSOR_POS ? fontWidth / 2 : 0 ) ) / fontWidth;
+  if ( *column < 0 ) * column = 0;
+}
+
+
+
+/**
+ \brief Offset line start counters for a new vertical scroll position.
+ 
+ Offset the line starts array, mTopLineNum, mFirstChar and lastChar, for a new
+ vertical scroll position given by newTopLineNum.  If any currently displayed
+ lines will still be visible, salvage the line starts values, otherwise,
+ count lines from the nearest known line start (start or end of buffer, or
+ the closest value in the mLineStarts array)
+ 
+ \param newTopLineNum index into buffer
+ */
+void Fl_Text_Display::offset_line_starts( int newTopLineNum ) {
+  int oldTopLineNum = mTopLineNum;
+  int oldFirstChar = mFirstChar;
+  int lineDelta = newTopLineNum - oldTopLineNum;
+  int nVisLines = mNVisibleLines;
+  int *lineStarts = mLineStarts;
+  int i, lastLineNum;
+  Fl_Text_Buffer *buf = mBuffer;
+  
+  /* If there was no offset, nothing needs to be changed */
+  if ( lineDelta == 0 )
+    return;
+  
+  /* Find the new value for mFirstChar by counting lines from the nearest
+   known line start (start or end of buffer, or the closest value in the
+   lineStarts array) */
+  lastLineNum = oldTopLineNum + nVisLines - 1;
+  if ( newTopLineNum < oldTopLineNum && newTopLineNum < -lineDelta ) {
+    mFirstChar = skip_lines( 0, newTopLineNum - 1, true );
+  } else if ( newTopLineNum < oldTopLineNum ) {
+    mFirstChar = rewind_lines( mFirstChar, -lineDelta );
+  } else if ( newTopLineNum < lastLineNum ) {
+    mFirstChar = lineStarts[ newTopLineNum - oldTopLineNum ];
+  } else if ( newTopLineNum - lastLineNum < mNBufferLines - newTopLineNum ) {
+    mFirstChar = skip_lines( lineStarts[ nVisLines - 1 ],
+                            newTopLineNum - lastLineNum, true );
+  } else {
+    mFirstChar = rewind_lines( buf->length(), mNBufferLines - newTopLineNum + 1 );
+  }
+  
+  /* Fill in the line starts array */
+  if ( lineDelta < 0 && -lineDelta < nVisLines ) {
+    for ( i = nVisLines - 1; i >= -lineDelta; i-- )
+      lineStarts[ i ] = lineStarts[ i + lineDelta ];
+    calc_line_starts( 0, -lineDelta );
+  } else if ( lineDelta > 0 && lineDelta < nVisLines ) {
+    for ( i = 0; i < nVisLines - lineDelta; i++ )
+      lineStarts[ i ] = lineStarts[ i + lineDelta ];
+    calc_line_starts( nVisLines - lineDelta, nVisLines - 1 );
+  } else
+    calc_line_starts( 0, nVisLines );
+  
+  /* Set lastChar and mTopLineNum */
+  calc_last_char();
+  mTopLineNum = newTopLineNum;
+  
+  /* If we're numbering lines or being asked to maintain an absolute line
+   number, re-calculate the absolute line number */
+  absolute_top_line_number(oldFirstChar);
+}
+
+
+
+/**
+ \brief Update line start arrays and variables.
+
+ Update the line starts array, mTopLineNum, mFirstChar and lastChar for this
+ text display after a modification to the text buffer, given by the
+ position \p pos where the change began, and the numbers of characters
+ and lines inserted and deleted.
+
+ \param pos index into buffer of recent changes
+ \param charsInserted number of bytes(!) inserted
+ \param charsDeleted number of bytes(!) deleted
+ \param linesInserted number of lines
+ \param linesDeleted number of lines
+ \param[out] scrolled set to 1 if the text display needs to be scrolled
+ */
+void Fl_Text_Display::update_line_starts(int pos, int charsInserted,
+                                         int charsDeleted, int linesInserted, 
+                                         int linesDeleted, int *scrolled ) {
+  IS_UTF8_ALIGNED2(buffer(), pos)
+
+  int *lineStarts = mLineStarts;
+  int i, lineOfPos, lineOfEnd, nVisLines = mNVisibleLines;
+  int charDelta = charsInserted - charsDeleted;
+  int lineDelta = linesInserted - linesDeleted;
+  
+  /* If all of the changes were before the displayed text, the display
+   doesn't change, just update the top line num and offset the line
+   start entries and first and last characters */
+  if ( pos + charsDeleted < mFirstChar ) {
+    mTopLineNum += lineDelta;
+    for ( i = 0; i < nVisLines && lineStarts[i] != -1; i++ )
+      lineStarts[ i ] += charDelta;
+    mFirstChar += charDelta;
+    mLastChar += charDelta;
+    *scrolled = 0;
+    return;
+  }
+  
+  /* The change began before the beginning of the displayed text, but
+   part or all of the displayed text was deleted */
+  if ( pos < mFirstChar ) {
+    /* If some text remains in the window, anchor on that  */
+    if ( position_to_line( pos + charsDeleted, &lineOfEnd ) &&
+        ++lineOfEnd < nVisLines && lineStarts[ lineOfEnd ] != -1 ) {
+      mTopLineNum = max( 1, mTopLineNum + lineDelta );
+      mFirstChar = rewind_lines(lineStarts[ lineOfEnd ] + charDelta, lineOfEnd );
+      /* Otherwise anchor on original line number and recount everything */
+    } else {
+      if ( mTopLineNum > mNBufferLines + lineDelta ) {
+        mTopLineNum = 1;
+        mFirstChar = 0;
+      } else
+        mFirstChar = skip_lines( 0, mTopLineNum - 1, true );
+    }
+    calc_line_starts( 0, nVisLines - 1 );
+    /* calculate lastChar by finding the end of the last displayed line */
+    calc_last_char();
+    *scrolled = 1;
+    return;
+  }
+  
+  /* If the change was in the middle of the displayed text (it usually is),
+   salvage as much of the line starts array as possible by moving and
+   offsetting the entries after the changed area, and re-counting the
+   added lines or the lines beyond the salvaged part of the line starts
+   array */
+  if ( pos <= mLastChar ) {
+    /* find line on which the change began */
+    position_to_line( pos, &lineOfPos );
+    /* salvage line starts after the changed area */
+    if ( lineDelta == 0 ) {
+      for ( i = lineOfPos + 1; i < nVisLines && lineStarts[ i ] != -1; i++ )
+        lineStarts[ i ] += charDelta;
+    } else if ( lineDelta > 0 ) {
+      for ( i = nVisLines - 1; i >= lineOfPos + lineDelta + 1; i-- )
+        lineStarts[ i ] = lineStarts[ i - lineDelta ] +
+        ( lineStarts[ i - lineDelta ] == -1 ? 0 : charDelta );
+    } else /* (lineDelta < 0) */ {
+      for ( i = max( 0, lineOfPos + 1 ); i < nVisLines + lineDelta; i++ )
+        lineStarts[ i ] = lineStarts[ i - lineDelta ] +
+        ( lineStarts[ i - lineDelta ] == -1 ? 0 : charDelta );
+    }
+    /* fill in the missing line starts */
+    if ( linesInserted >= 0 )
+      calc_line_starts( lineOfPos + 1, lineOfPos + linesInserted );
+    if ( lineDelta < 0 )
+      calc_line_starts( nVisLines + lineDelta, nVisLines );
+    /* calculate lastChar by finding the end of the last displayed line */
+    calc_last_char();
+    *scrolled = 0;
+    return;
+  }
+  
+  /* Change was past the end of the displayed text, but displayable by virtue
+   of being an insert at the end of the buffer into visible blank lines */
+  if ( empty_vlines() ) {
+    position_to_line( pos, &lineOfPos );
+    calc_line_starts( lineOfPos, lineOfPos + linesInserted );
+    calc_last_char();
+    *scrolled = 0;
+    return;
+  }
+  
+  /* Change was beyond the end of the buffer and not visible, do nothing */
+  *scrolled = 0;
+}
+
+
+
+/**
+ \brief Update the line start arrays.
+ 
+ Scan through the text in the "textD"'s buffer and recalculate the line
+ starts array values beginning at index "startLine" and continuing through
+ (including) "endLine".  It assumes that the line starts entry preceding
+ "startLine" (or mFirstChar if startLine is 0) is good, and re-counts
+ newlines to fill in the requested entries.  Out of range values for
+ "startLine" and "endLine" are acceptable.
+ 
+ \param startLine, endLine range of lines to scan as line numbers
+ */
+void Fl_Text_Display::calc_line_starts( int startLine, int endLine ) {
+  int startPos, bufLen = mBuffer->length();
+  int line, lineEnd, nextLineStart, nVis = mNVisibleLines;
+  int *lineStarts = mLineStarts;
+  
+  /* Clean up (possibly) messy input parameters */
+  if ( endLine < 0 ) endLine = 0;
+  if ( endLine >= nVis ) endLine = nVis - 1;
+  if ( startLine < 0 ) startLine = 0;
+  if ( startLine >= nVis ) startLine = nVis - 1;
+  if ( startLine > endLine )
+    return;
+  
+  /* Find the last known good line number -> position mapping */
+  if ( startLine == 0 ) {
+    lineStarts[ 0 ] = mFirstChar;
+    startLine = 1;
+  }
+  startPos = lineStarts[ startLine - 1 ];
+  
+  /* If the starting position is already past the end of the text,
+   fill in -1's (means no text on line) and return */
+  if ( startPos == -1 ) {
+    for ( line = startLine; line <= endLine; line++ )
+      lineStarts[ line ] = -1;
+    return;
+  }
+  
+  /* Loop searching for ends of lines and storing the positions of the
+   start of the next line in lineStarts */
+  for ( line = startLine; line <= endLine; line++ ) {
+    find_line_end(startPos, true, &lineEnd, &nextLineStart);
+    startPos = nextLineStart;
+    if ( startPos >= bufLen ) {
+      /* If the buffer ends with a newline or line break, put
+       buf->length() in the next line start position (instead of
+       a -1 which is the normal marker for an empty line) to
+       indicate that the cursor may safely be displayed there */
+      if ( line == 0 || ( lineStarts[ line - 1 ] != bufLen &&
+                         lineEnd != nextLineStart ) ) {
+        lineStarts[ line ] = bufLen;
+        line++;
+      }
+      break;
+    }
+    lineStarts[ line ] = startPos;
+  }
+  
+  /* Set any entries beyond the end of the text to -1 */
+  for ( ; line <= endLine; line++ )
+    lineStarts[ line ] = -1;
+}
+
+
+
+/**
+ \brief Update last display character index.
+ 
+ Given a Fl_Text_Display with a complete, up-to-date lineStarts array, update
+ the lastChar entry to point to the last buffer position displayed.
+ */
+void Fl_Text_Display::calc_last_char() {
+  int i;
+  for (i = mNVisibleLines - 1; i >= 0 && mLineStarts[i] == -1; i--) ;
+  mLastChar = i < 0 ? 0 : line_end(mLineStarts[i], true);
+}
+
+
+
+/**  
+ \brief Scrolls the current buffer to start at the specified line and column.
+ \param topLineNum top line number
+ \param horizOffset column number
+ \todo Column numbers make little sense here.
+ */
+void Fl_Text_Display::scroll(int topLineNum, int horizOffset) {
+  mTopLineNumHint = topLineNum;
+  mHorizOffsetHint = horizOffset;
+  resize(x(), y(), w(), h());
+}
+
+
+
+/**  
+ \brief Scrolls the current buffer to start at the specified line and column.
+ \param topLineNum top line number
+ \param horizOffset in pixels
+ \return 0 if nothing changed, 1 if we scrolled
+ */
+int Fl_Text_Display::scroll_(int topLineNum, int horizOffset) {
+  /* Limit the requested scroll position to allowable values */
+  if (topLineNum > mNBufferLines + 3 - mNVisibleLines)
+    topLineNum = mNBufferLines + 3 - mNVisibleLines;
+  if (topLineNum < 1) topLineNum = 1;
+  
+  if (horizOffset > longest_vline() - text_area.w)
+    horizOffset = longest_vline() - text_area.w;
+  if (horizOffset < 0) horizOffset = 0;
+  
+  /* Do nothing if scroll position hasn't actually changed or there's no
+   window to draw in yet */
+  if (mHorizOffset == horizOffset && mTopLineNum == topLineNum)
+    return 0;
+  
+  /* If the vertical scroll position has changed, update the line
+   starts array and related counters in the text display */
+  offset_line_starts(topLineNum);
+  
+  /* Just setting mHorizOffset is enough information for redisplay */
+  mHorizOffset = horizOffset;
+  
+  // redraw all text
+  damage(FL_DAMAGE_EXPOSE);
+  return 1;
+}
+
+
+
+/**
+ \brief Update vertical scrollbar.
+ 
+ Update the minimum, maximum, slider size, page increment, and value
+ for vertical scrollbar.
+ */
+void Fl_Text_Display::update_v_scrollbar() {
+  /* The vertical scrollbar value and slider size directly represent the top
+   line number, and the number of visible lines respectively.  The scroll
+   bar maximum value is chosen to generally represent the size of the whole
+   buffer, with minor adjustments to keep the scrollbar widget happy */
+#ifdef DEBUG
+  printf("Fl_Text_Display::update_v_scrollbar():\n"
+         "    mTopLineNum=%d, mNVisibleLines=%d, mNBufferLines=%d\n",
+	 mTopLineNum, mNVisibleLines, mNBufferLines);
+#endif // DEBUG
+  
+  mVScrollBar->value(mTopLineNum, mNVisibleLines, 1, mNBufferLines+2);
+  mVScrollBar->linesize(3);
+}
+
+
+/**
+ \brief Update vertical scrollbar.
+ 
+ Update the minimum, maximum, slider size, page increment, and value
+ for the horizontal scrollbar.
+ */
+void Fl_Text_Display::update_h_scrollbar() {
+  int sliderMax = max(longest_vline(), text_area.w + mHorizOffset);
+  mHScrollBar->value( mHorizOffset, text_area.w, 0, sliderMax );
+}
+
+
+
+/**
+ \brief Callbacks for drag or valueChanged on scrollbars.
+ */
+void Fl_Text_Display::v_scrollbar_cb(Fl_Scrollbar* b, Fl_Text_Display* textD) {
+  if (b->value() == textD->mTopLineNum) return;
+  textD->scroll(b->value(), textD->mHorizOffset);
+}
+
+
+
+/**
+ \brief Callbacks for drag or valueChanged on scrollbars.
+ */
+void Fl_Text_Display::h_scrollbar_cb(Fl_Scrollbar* b, Fl_Text_Display* textD) {
+  if (b->value() == textD->mHorizOffset) return;
+  textD->scroll(textD->mTopLineNum, b->value());
+}
+
+
+
+/**
+ \brief Refresh the line number area.  
+ 
+ If clearAll is False, writes only over the character cell areas.  Setting 
+ clearAll to True will clear out any stray marks outside of the character cell 
+ area, which might have been left from before a resize or font change.
+ 
+ This function is not used.
+ */
+void Fl_Text_Display::draw_line_numbers(bool /*clearAll*/) {
+#if 0
+  int y, line, visLine, nCols, lineStart;
+  char lineNumString[12];
+  int lineHeight = mMaxsize ? mMaxsize : textsize_;
+  int charWidth = TMPFONTWIDTH;   //mFontStruct->max_bounds.width;
+  
+  /* Don't draw if mLineNumWidth == 0 (line numbers are hidden), or widget is
+   not yet realized */
+  if (mLineNumWidth == 0 || visible_r())
+    return;
+  
+  /* GC is allocated on demand, since not everyone will use line numbering */
+  if (textD->lineNumGC == NULL) {
+    XGCValues values;
+    values.foreground = textD->lineNumFGPixel;
+    values.background = textD->bgPixel;
+    values.font = textD->fontStruct->fid;
+    textD->lineNumGC = XtGetGC(textD->w,
+                               GCFont| GCForeground | GCBackground, &values);
+  }
+  
+  /* Erase the previous contents of the line number area, if requested */
+  if (clearAll)
+    XClearArea(XtDisplay(textD->w), XtWindow(textD->w), textD->lineNumLeft,
+               textD->top, textD->lineNumWidth, textD->height, False);
+  
+  /* Draw the line numbers, aligned to the text */
+  nCols = min(11, textD->lineNumWidth / charWidth);
+  y = textD->top;
+  line = getAbsTopLineNum(textD);
+  for (visLine=0; visLine < textD->nVisibleLines; visLine++) {
+    lineStart = textD->lineStarts[visLine];
+    if (lineStart != -1 && (lineStart==0 ||
+                            BufGetCharacter(textD->buffer, lineStart-1)=='\n')) {
+      sprintf(lineNumString, "%*d", nCols, line);
+      XDrawImageString(XtDisplay(textD->w), XtWindow(textD->w),
+                       textD->lineNumGC, textD->lineNumLeft, y + textD->ascent,
+                       lineNumString, strlen(lineNumString));
+      line++;
+    } else {
+      XClearArea(XtDisplay(textD->w), XtWindow(textD->w),
+                 textD->lineNumLeft, y, textD->lineNumWidth,
+                 textD->ascent + textD->descent, False);
+      if (visLine == 0)
+        line++;
+    }
+    y += lineHeight;
+  }
+#endif
+}
+
+static int max( int i1, int i2 ) {
+  return i1 >= i2 ? i1 : i2;
+}
+
+static int min( int i1, int i2 ) {
+  return i1 <= i2 ? i1 : i2;
+}
+
+
+
+/**
+ Count the number of newlines in a null-terminated text string;
+ */
+static int countlines( const char *string ) {
+  IS_UTF8_ALIGNED(string)
+
+  const char * c;
+  int lineCount = 0;
+  
+  if (!string) return 0;
+  
+  for ( c = string; *c != '\0'; c++ )
+    if ( *c == '\n' ) lineCount++;
+  return lineCount;
+}
+
+
+
+
+/**
+ \brief Returns the width in pixels of the displayed line pointed to by "visLineNum".
+ \param visLineNum index into visible lines array
+ \return width of line in pixels
+ */
+int Fl_Text_Display::measure_vline( int visLineNum ) const {
+  int lineLen = vline_length( visLineNum );
+  int lineStartPos = mLineStarts[ visLineNum ];
+  if (lineStartPos < 0 || lineLen == 0) return 0;
+  return handle_vline(GET_WIDTH, lineStartPos, lineLen, 0, 0, 0, 0, 0, 0);
+}
+
+
+
+/**
+ \brief Return true if there are lines visible with no corresponding buffer text.
+ \return 1 if there are empty lines
+ */
+int Fl_Text_Display::empty_vlines() const {
+  return (mNVisibleLines > 0) && (mLineStarts[ mNVisibleLines - 1 ] == -1);
+}
+
+
+
+/**
+ \brief Count number of bytes in a visible line.
+ 
+ Return the length of a line (number of bytes) by examining
+ entries in the line starts array rather than by scanning for newlines.
+ 
+ \param visLineNum index of line in visible line array
+ \return number of bytes in this line
+ */
+int Fl_Text_Display::vline_length( int visLineNum ) const {
+  int nextLineStart, lineStartPos;
+  
+  if (visLineNum < 0 || visLineNum >= mNVisibleLines)
+    return (0);
+  
+  lineStartPos = mLineStarts[ visLineNum ];
+  
+  if ( lineStartPos == -1 )
+    return 0;
+  
+  if ( visLineNum + 1 >= mNVisibleLines )
+    return mLastChar - lineStartPos;
+  
+  nextLineStart = mLineStarts[ visLineNum + 1 ];
+  if ( nextLineStart == -1 )
+    return mLastChar - lineStartPos;
+  
+  int nextLineStartMinus1 = buffer()->prev_char(nextLineStart);
+  if (wrap_uses_character(nextLineStartMinus1))
+    return nextLineStartMinus1 - lineStartPos;
+  
+  return nextLineStart - lineStartPos;
+}
+
+
+
+/**
+ \brief Wrapping calculations.
+ 
+ When continuous wrap is on, and the user inserts or deletes characters,
+ wrapping can happen before and beyond the changed position.  This routine
+ finds the extent of the changes, and counts the deleted and inserted lines
+ over that range.  It also attempts to minimize the size of the range to
+ what has to be counted and re-displayed, so the results can be useful
+ both for delimiting where the line starts need to be recalculated, and
+ for deciding what part of the text to redisplay.
+ 
+ \param deletedText
+ \param pos
+ \param nInserted
+ \param nDeleted
+ \param modRangeStart
+ \param modRangeEnd
+ \param linesInserted
+ \param linesDeleted
+ */
+void Fl_Text_Display::find_wrap_range(const char *deletedText, int pos,
+                                      int nInserted, int nDeleted, 
+                                      int *modRangeStart, int *modRangeEnd,
+                                      int *linesInserted, int *linesDeleted) {
+  IS_UTF8_ALIGNED(deletedText)
+  IS_UTF8_ALIGNED2(buffer(), pos)
+
+  int length, retPos, retLines, retLineStart, retLineEnd;
+  Fl_Text_Buffer *deletedTextBuf, *buf = buffer();
+  int nVisLines = mNVisibleLines;
+  int *lineStarts = mLineStarts;
+  int countFrom, countTo, lineStart, adjLineStart, i;
+  int visLineNum = 0, nLines = 0;
+  
+  /*
+   ** Determine where to begin searching: either the previous newline, or
+   ** if possible, limit to the start of the (original) previous displayed
+   ** line, using information from the existing line starts array
+   */
+  if (pos >= mFirstChar && pos <= mLastChar) {
+    for (i=nVisLines-1; i>0; i--) {
+      if (lineStarts[i] != -1 && pos >= lineStarts[i]) {
+        break;
+      }
+    }
+    if (i > 0) {
+      countFrom = lineStarts[i-1];
+      visLineNum = i-1;
+    } else {
+      countFrom = buf->line_start(pos);
+    }
+  } else {
+    countFrom = buf->line_start(pos);
+  }
+  
+  IS_UTF8_ALIGNED2(buf, countFrom)
+  
+  /*
+   ** Move forward through the (new) text one line at a time, counting
+   ** displayed lines, and looking for either a real newline, or for the
+   ** line starts to re-sync with the original line starts array
+   */
+  lineStart = countFrom;
+  *modRangeStart = countFrom;
+  for (;;) {
+    
+    /* advance to the next line.  If the line ended in a real newline
+     or the end of the buffer, that's far enough */
+    wrapped_line_counter(buf, lineStart, buf->length(), 1, true, 0,
+                         &retPos, &retLines, &retLineStart, &retLineEnd);
+    if (retPos >= buf->length()) {
+      countTo = buf->length();
+      *modRangeEnd = countTo;
+      if (retPos != retLineEnd)
+        nLines++;
+      break;
+    } else {
+      lineStart = retPos;
+    }
+    nLines++;
+    if (lineStart > pos + nInserted && buf->char_at(buf->prev_char(lineStart)) == '\n') {
+      countTo = lineStart;
+      *modRangeEnd = lineStart;
+      break;
+    }
+    
+    /* Don't try to resync in continuous wrap mode with non-fixed font
+     sizes; it would result in a chicken-and-egg dependency between
+     the calculations for the inserted and the deleted lines. 
+     If we're in that mode, the number of deleted lines is calculated in
+     advance, without resynchronization, so we shouldn't resynchronize
+     for the inserted lines either. */
+    if (mSuppressResync)
+      continue;
+    
+    /* check for synchronization with the original line starts array
+     before pos, if so, the modified range can begin later */
+    if (lineStart <= pos) {
+      while (visLineNum<nVisLines && lineStarts[visLineNum] < lineStart)
+        visLineNum++;
+      if (visLineNum < nVisLines && lineStarts[visLineNum] == lineStart) {
+        countFrom = lineStart;
+        nLines = 0;
+        if (visLineNum+1 < nVisLines && lineStarts[visLineNum+1] != -1)
+          *modRangeStart = min(pos, buf->prev_char(lineStarts[visLineNum+1]));
+        else
+          *modRangeStart = countFrom;
+      } else
+        *modRangeStart = min(*modRangeStart, buf->prev_char(lineStart));
+    }
+    
+    /* check for synchronization with the original line starts array
+     after pos, if so, the modified range can end early */
+    else if (lineStart > pos + nInserted) {
+      adjLineStart = lineStart - nInserted + nDeleted;
+      while (visLineNum<nVisLines && lineStarts[visLineNum]<adjLineStart)
+        visLineNum++;
+      if (visLineNum < nVisLines && lineStarts[visLineNum] != -1 &&
+          lineStarts[visLineNum] == adjLineStart) {
+        countTo = line_end(lineStart, true);
+        *modRangeEnd = lineStart;
+        break;
+      }
+    }
+  }
+  *linesInserted = nLines;
+  
+  
+  /* Count deleted lines between countFrom and countTo as the text existed
+   before the modification (that is, as if the text between pos and
+   pos+nInserted were replaced by "deletedText").  This extra context is
+   necessary because wrapping can occur outside of the modified region
+   as a result of adding or deleting text in the region. This is done by
+   creating a textBuffer containing the deleted text and the necessary
+   additional context, and calling the wrappedLineCounter on it.
+   
+   NOTE: This must not be done in continuous wrap mode when the font
+   width is not fixed. In that case, the calculation would try
+   to access style information that is no longer available (deleted
+   text), or out of date (updated highlighting), possibly leading 
+   to completely wrong calculations and/or even crashes eventually.
+   (This is not theoretical; it really happened.)
+   
+   In that case, the calculation of the number of deleted lines
+   has happened before the buffer was modified (only in that case,
+   because resynchronization of the line starts is impossible
+   in that case, which makes the whole calculation less efficient).
+   */
+  if (mSuppressResync) {
+    *linesDeleted = mNLinesDeleted;
+    mSuppressResync = 0;
+    return;
+  }
+  
+  length = (pos-countFrom) + nDeleted +(countTo-(pos+nInserted));
+  deletedTextBuf = new Fl_Text_Buffer(length);
+  deletedTextBuf->copy(buffer(), countFrom, pos, 0);
+  if (nDeleted != 0)
+    deletedTextBuf->insert(pos-countFrom, deletedText);
+  deletedTextBuf->copy(buffer(), pos+nInserted, countTo, pos-countFrom+nDeleted);
+  /* Note that we need to take into account an offset for the style buffer:
+   the deletedTextBuf can be out of sync with the style buffer. */
+  wrapped_line_counter(deletedTextBuf, 0, length, INT_MAX, true, countFrom, 
+                       &retPos, &retLines, &retLineStart, &retLineEnd, false);
+  delete deletedTextBuf;
+  *linesDeleted = retLines;
+  mSuppressResync = 0;
+}
+
+
+
+/**
+ \brief Wrapping calculations.
+ 
+ This is a stripped-down version of the findWrapRange() function above,
+ intended to be used to calculate the number of "deleted" lines during
+ a buffer modification. It is called _before_ the modification takes place.
+ 
+ This function should only be called in continuous wrap mode with a
+ non-fixed font width. In that case, it is impossible to calculate
+ the number of deleted lines, because the necessary style information 
+ is no longer available _after_ the modification. In other cases, we
+ can still perform the calculation afterwards (possibly even more
+ efficiently).
+
+ \param pos
+ \param nDeleted
+ */
+void Fl_Text_Display::measure_deleted_lines(int pos, int nDeleted) {
+  IS_UTF8_ALIGNED2(buffer(), pos)
+
+  int retPos, retLines, retLineStart, retLineEnd;
+  Fl_Text_Buffer *buf = buffer();
+  int nVisLines = mNVisibleLines;
+  int *lineStarts = mLineStarts;
+  int countFrom, lineStart;
+  int visLineNum = 0, nLines = 0, i;
+  /*
+   ** Determine where to begin searching: either the previous newline, or
+   ** if possible, limit to the start of the (original) previous displayed
+   ** line, using information from the existing line starts array
+   */
+  if (pos >= mFirstChar && pos <= mLastChar) {
+    for (i=nVisLines-1; i>0; i--)
+      if (lineStarts[i] != -1 && pos >= lineStarts[i])
+        break;
+    if (i > 0) {
+      countFrom = lineStarts[i-1];
+      visLineNum = i-1;
+    } else
+      countFrom = buf->line_start(pos);
+  } else
+    countFrom = buf->line_start(pos);
+  
+  /*
+   ** Move forward through the (new) text one line at a time, counting
+   ** displayed lines, and looking for either a real newline, or for the
+   ** line starts to re-sync with the original line starts array
+   */
+  lineStart = countFrom;
+  for (;;) {
+    /* advance to the next line.  If the line ended in a real newline
+     or the end of the buffer, that's far enough */
+    wrapped_line_counter(buf, lineStart, buf->length(), 1, true, 0,
+                         &retPos, &retLines, &retLineStart, &retLineEnd);
+    if (retPos >= buf->length()) {
+      if (retPos != retLineEnd)
+        nLines++;
+      break;
+    } else
+      lineStart = retPos;
+    nLines++;
+    if (lineStart > pos + nDeleted && buf->char_at(lineStart-1) == '\n') {
+      break;
+    }
+    
+    /* Unlike in the findWrapRange() function above, we don't try to 
+     resync with the line starts, because we don't know the length 
+     of the inserted text yet, nor the updated style information. 
+     
+     Because of that, we also shouldn't resync with the line starts
+     after the modification either, because we must perform the
+     calculations for the deleted and inserted lines in the same way. 
+     
+     This can result in some unnecessary recalculation and redrawing
+     overhead, and therefore we should only use this two-phase mode
+     of calculation when it's really needed (continuous wrap + variable
+     font width). */
+  }
+  mNLinesDeleted = nLines;
+  mSuppressResync = 1;
+}
+
+
+
+/**
+ \brief Wrapping calculations.
+ 
+ Count forward from startPos to either maxPos or maxLines (whichever is
+ reached first), and return all relevant positions and line count.
+ The provided textBuffer may differ from the actual text buffer of the
+ widget. In that case it must be a (partial) copy of the actual text buffer
+ and the styleBufOffset argument must indicate the starting position of the
+ copy, to take into account the correct style information.
+
+ \param buf
+ \param startPos
+ \param maxPos
+ \param maxLines
+ \param startPosIsLineStart
+ \param styleBufOffset
+
+ \param[out] retPos Position where counting ended.  When counting lines, the
+    position returned is the start of the line "maxLines" lines 
+    beyond "startPos".
+ \param[out] retLines Number of line breaks counted
+ \param[out] retLineStart Start of the line where counting ended
+ \param[out] retLineEnd End position of the last line traversed
+ \param[out] countLastLineMissingNewLine
+ */
+void Fl_Text_Display::wrapped_line_counter(Fl_Text_Buffer *buf, int startPos,
+                                           int maxPos, int maxLines, bool startPosIsLineStart, int styleBufOffset,
+                                           int *retPos, int *retLines, int *retLineStart, int *retLineEnd,
+                                           bool countLastLineMissingNewLine) const {
+  IS_UTF8_ALIGNED2(buf, startPos)
+  IS_UTF8_ALIGNED2(buf, maxPos)
+
+  int lineStart, newLineStart = 0, b, p, colNum, wrapMarginPix;
+  int i, foundBreak;
+  double width;
+  int nLines = 0;
+  unsigned int c;
+  
+  /* Set the wrap margin to the wrap column or the view width */
+  if (mWrapMarginPix != 0) {
+    wrapMarginPix = mWrapMarginPix;
+  } else {
+    wrapMarginPix = text_area.w;
+  }
+  
+  /* Find the start of the line if the start pos is not marked as a
+   line start. */
+  if (startPosIsLineStart)
+    lineStart = startPos;
+  else
+    lineStart = line_start(startPos);
+  
+  /*
+   ** Loop until position exceeds maxPos or line count exceeds maxLines.
+   ** (actually, continues beyond maxPos to end of line containing maxPos,
+   ** in case later characters cause a word wrap back before maxPos)
+   */
+  colNum = 0;
+  width = 0;
+  for (p=lineStart; p<buf->length(); p=buf->next_char(p)) {
+    c = buf->char_at(p);  // UCS-4
+    
+    /* If the character was a newline, count the line and start over,
+     otherwise, add it to the width and column counts */
+    if (c == '\n') {
+      if (p >= maxPos) {
+        *retPos = maxPos;
+        *retLines = nLines;
+        *retLineStart = lineStart;
+        *retLineEnd = maxPos;
+        return;
+      }
+      nLines++;
+      int p1 = buf->next_char(p);
+      if (nLines >= maxLines) {
+        *retPos = p1;
+        *retLines = nLines;
+        *retLineStart = p1;
+        *retLineEnd = p;
+        return;
+      }
+      lineStart = p1;
+      colNum = 0;
+      width = 0;
+    } else {
+      const char *s = buf->address(p);
+      colNum++;
+      // FIXME: it is not a good idea to simply add character widths because on
+      // some platforms, the width is a floating point value and depends on the 
+      // previous character as well.
+      width += measure_proportional_character(s, (int)width, p+styleBufOffset);
+    }
+    
+    /* If character exceeded wrap margin, find the break point and wrap there */
+    if (width > wrapMarginPix) {
+      foundBreak = false;
+      for (b=p; b>=lineStart; b=buf->prev_char(b)) {
+        c = buf->char_at(b);
+        if (c == '\t' || c == ' ') {
+          newLineStart = buf->next_char(b);
+          colNum = 0;
+          width = 0;
+          int iMax = buf->next_char(p);
+          for (i=buf->next_char(b); i<iMax; i = buf->next_char(i)) {
+            width += measure_proportional_character(buf->address(i), (int)width, 
+                                                    i+styleBufOffset);
+            colNum++;
+          }
+          foundBreak = true;
+          break;
+        }
+      }
+      if (!foundBreak) { /* no whitespace, just break at margin */
+        newLineStart = max(p, buf->next_char(lineStart));
+        const char *s = buf->address(b);
+        colNum++;
+        width = measure_proportional_character(s, 0, p+styleBufOffset);
+      }
+      if (p >= maxPos) {
+        *retPos = maxPos;
+        *retLines = maxPos < newLineStart ? nLines : nLines + 1;
+        *retLineStart = maxPos < newLineStart ? lineStart : newLineStart;
+        *retLineEnd = maxPos;
+        return;
+      }
+      nLines++;
+      if (nLines >= maxLines) {
+        *retPos = foundBreak ? buf->next_char(b) : max(p, buf->next_char(lineStart));
+        *retLines = nLines;
+        *retLineStart = lineStart;
+        *retLineEnd = foundBreak ? b : p;
+        return;
+      }
+      lineStart = newLineStart;
+    }
+  }
+  
+  /* reached end of buffer before reaching pos or line target */
+  *retPos = buf->length();
+  *retLines = nLines;
+  if (countLastLineMissingNewLine && colNum > 0) 
+    *retLines = buf->next_char(*retLines);
+  *retLineStart = lineStart;
+  *retLineEnd = buf->length();
+}
+
+
+
+/**
+ \brief Wrapping calculations.
+ 
+ Measure the width in pixels of the first character of string "s" at a
+ particular column "colNum" and buffer position "pos".  This is for measuring
+ characters in proportional or mixed-width highlighting fonts.
+
+ A note about proportional and mixed-width fonts: the mixed width and
+ proportional font code in nedit does not get much use in general editing,
+ because nedit doesn't allow per-language-mode fonts, and editing programs
+ in a proportional font is usually a bad idea, so very few users would
+ choose a proportional font as a default.  There are still probably mixed-
+ width syntax highlighting cases where things don't redraw properly for
+ insertion/deletion, though static display and wrapping and resizing
+ should now be solid because they are now used for online help display.
+ 
+ \param s text string
+ \param xPix x pixel position needed for calculating tab widths
+ \param pos offset within string
+ \return width of character in pixels
+ */
+double Fl_Text_Display::measure_proportional_character(const char *s, int xPix, int pos) const {
+  IS_UTF8_ALIGNED(s)
+  
+  if (*s=='\t') {
+    int tab = (int)col_to_x(mBuffer->tab_distance());
+    return (((xPix/tab)+1)*tab) - xPix;
+  }
+  
+  int charLen = fl_utf8len1(*s), style = 0;
+  if (mStyleBuffer) {
+    style = mStyleBuffer->byte_at(pos);
+  }
+  return string_width(s, charLen, style);
+}
+
+
+
+/**
+ \brief Finds both the end of the current line and the start of the next line.  
+ 
+ Why?
+ In continuous wrap mode, if you need to know both, figuring out one from the
+ other can be expensive or error prone.  The problem comes when there's a
+ trailing space or tab just before the end of the buffer.  To translate an
+ end of line value to or from the next lines start value, you need to know
+ whether the trailing space or tab is being used as a line break or just a
+ normal character, and to find that out would otherwise require counting all
+ the way back to the beginning of the line.
+ 
+ \param startPos
+ \param startPosIsLineStart
+ \param[out] lineEnd
+ \param[out] nextLineStart
+ */
+void Fl_Text_Display::find_line_end(int startPos, bool startPosIsLineStart,
+                                    int *lineEnd, int *nextLineStart) const {
+  IS_UTF8_ALIGNED2(buffer(), startPos)
+
+  int retLines, retLineStart;
+  
+  /* if we're not wrapping use more efficient BufEndOfLine */
+  if (!mContinuousWrap) {
+    int le = buffer()->line_end(startPos);
+    int ls = buffer()->next_char(le);
+    *lineEnd = le;
+    *nextLineStart = min(buffer()->length(), ls);
+    return;
+  }
+  
+  /* use the wrapped line counter routine to count forward one line */
+  wrapped_line_counter(buffer(), startPos, buffer()->length(),
+                       1, startPosIsLineStart, 0, nextLineStart, &retLines,
+                       &retLineStart, lineEnd);
+}
+
+
+
+/**
+ \brief Check if the line break is caused by a \\n or by line wrapping.
+ 
+ Line breaks in continuous wrap mode usually happen at newlines or
+ whitespace.  This line-terminating character is not included in line
+ width measurements and has a special status as a non-visible character.
+ However, lines with no whitespace are wrapped without the benefit of a
+ line terminating character, and this distinction causes endless trouble
+ with all of the text display code which was originally written without
+ continuous wrap mode and always expects to wrap at a newline character.
+
+ Given the position of the end of the line, as returned by TextDEndOfLine
+ or BufEndOfLine, this returns true if there is a line terminating
+ character, and false if there's not.  On the last character in the
+ buffer, this function can't tell for certain whether a trailing space was
+ used as a wrap point, and just guesses that it wasn't.  So if an exact
+ accounting is necessary, don't use this function.
+ 
+ \param lineEndPos index of character where the line wraps
+ \return 1 if a \\n character causes the line wrap
+ */ 
+int Fl_Text_Display::wrap_uses_character(int lineEndPos) const {
+  IS_UTF8_ALIGNED2(buffer(), lineEndPos)
+
+  unsigned int c;
+  
+  if (!mContinuousWrap || lineEndPos == buffer()->length())
+    return 1;
+  
+  c = buffer()->char_at(lineEndPos);
+  return c == '\n' || ((c == '\t' || c == ' ') &&
+                       lineEndPos + 1 < buffer()->length());
+}
+
+
+
+/**
+ \brief I don't know what this does!
+ 
+ Extend the range of a redraw request (from *start to *end) with additional
+ redraw requests resulting from changes to the attached style buffer (which
+ contains auxiliary information for coloring or styling text).
+ 
+ \param startpos ??
+ \param endpos ??
+ 
+ \todo Unicode?
+ */
+void Fl_Text_Display::extend_range_for_styles( int *startpos, int *endpos ) {
+  IS_UTF8_ALIGNED2(buffer(), (*startpos))  
+  IS_UTF8_ALIGNED2(buffer(), (*endpos))  
+  
+  Fl_Text_Selection * sel = mStyleBuffer->primary_selection();
+  int extended = 0;
+  
+  /* The peculiar protocol used here is that modifications to the style
+   buffer are marked by selecting them with the buffer's primary Fl_Text_Selection.
+   The style buffer is usually modified in response to a modify callback on
+   the text buffer BEFORE Fl_Text_Display.c's modify callback, so that it can keep
+   the style buffer in step with the text buffer.  The style-update
+   callback can't just call for a redraw, because Fl_Text_Display hasn't processed
+   the original text changes yet.  Anyhow, to minimize redrawing and to
+   avoid the complexity of scheduling redraws later, this simple protocol
+   tells the text display's buffer modify callback to extend its redraw
+   range to show the text color/and font changes as well. */
+  if ( sel->selected() ) {
+    if ( sel->start() < *startpos ) {
+      *startpos = sel->start();
+      // somewhere while deleting, alignment is lost. We do this just to be sure.
+      *startpos = buffer()->utf8_align(*startpos);
+      IS_UTF8_ALIGNED2(buffer(), (*startpos))  
+      extended = 1;
+    }
+    if ( sel->end() > *endpos ) {
+      *endpos = sel->end();
+      *endpos = buffer()->utf8_align(*endpos);
+      IS_UTF8_ALIGNED2(buffer(), (*endpos))  
+      extended = 1;
+    }
+  }
+  
+  /* If the Fl_Text_Selection was extended due to a style change, and some of the
+   fonts don't match in spacing, extend redraw area to end of line to
+   redraw characters exposed by possible font size changes */
+  if ( extended )
+    *endpos = mBuffer->line_end( *endpos ) + 1;
+  
+  IS_UTF8_ALIGNED2(buffer(), (*endpos))
+}
+
+
+
+/**
+ \brief Draw the widget.
+ 
+ This function tries to limit drawing to smaller areas if possible.
+ */
+void Fl_Text_Display::draw(void) {
+  // don't even try if there is no associated text buffer!
+  if (!buffer()) { draw_box(); return; }
+  
+  fl_push_clip(x(),y(),w(),h());	// prevent drawing outside widget area
+  
+  // draw the non-text, non-scrollbar areas.
+  if (damage() & FL_DAMAGE_ALL) {
+    //    printf("drawing all (box = %d)\n", box());
+    if (Fl_Surface_Device::surface()->class_name() == Fl_Printer::class_id) {
+      // if to printer, draw the background
+      fl_rectf(text_area.x, text_area.y, text_area.w, text_area.h, color() );
+    }
+    // draw the box()
+    int W = w(), H = h();
+    draw_box(box(), x(), y(), W, H, color());
+    
+    if (mHScrollBar->visible())
+      W -= scrollbar_width();
+    if (mVScrollBar->visible())
+      H -= scrollbar_width();
+    
+    // left margin
+    fl_rectf(text_area.x-LEFT_MARGIN, text_area.y-TOP_MARGIN,
+             LEFT_MARGIN, text_area.h+TOP_MARGIN+BOTTOM_MARGIN,
+             color());
+    
+    // right margin
+    fl_rectf(text_area.x+text_area.w, text_area.y-TOP_MARGIN,
+             RIGHT_MARGIN, text_area.h+TOP_MARGIN+BOTTOM_MARGIN,
+             color());
+    
+    // top margin
+    fl_rectf(text_area.x, text_area.y-TOP_MARGIN,
+             text_area.w, TOP_MARGIN, color());
+    
+    // bottom margin
+    fl_rectf(text_area.x, text_area.y+text_area.h,
+             text_area.w, BOTTOM_MARGIN, color());
+    
+    // draw that little box in the corner of the scrollbars
+    if (mVScrollBar->visible() && mHScrollBar->visible())
+      fl_rectf(mVScrollBar->x(), mHScrollBar->y(),
+               mVScrollBar->w(), mHScrollBar->h(),
+               FL_GRAY);
+    
+    // blank the previous cursor protrusions
+  }
+  else if (damage() & (FL_DAMAGE_SCROLL | FL_DAMAGE_EXPOSE)) {
+    //    printf("blanking previous cursor extrusions at Y: %d\n", mCursorOldY);
+    // CET - FIXME - save old cursor position instead and just draw side needed?
+    fl_push_clip(text_area.x-LEFT_MARGIN,
+                 text_area.y,
+                 text_area.w+LEFT_MARGIN+RIGHT_MARGIN,
+                 text_area.h);
+    fl_rectf(text_area.x-LEFT_MARGIN, mCursorOldY,
+             LEFT_MARGIN, mMaxsize, color());
+    fl_rectf(text_area.x+text_area.w, mCursorOldY,
+             RIGHT_MARGIN, mMaxsize, color());
+    fl_pop_clip();
+  }
+  
+  // draw the scrollbars
+  if (damage() & (FL_DAMAGE_ALL | FL_DAMAGE_CHILD)) {
+    mVScrollBar->damage(FL_DAMAGE_ALL);
+    mHScrollBar->damage(FL_DAMAGE_ALL);
+  }
+  update_child(*mVScrollBar);
+  update_child(*mHScrollBar);
+  
+  // draw all of the text
+  if (damage() & (FL_DAMAGE_ALL | FL_DAMAGE_EXPOSE)) {
+    //printf("drawing all text\n");
+    int X, Y, W, H;
+    if (fl_clip_box(text_area.x, text_area.y, text_area.w, text_area.h,
+                    X, Y, W, H)) {
+      // Draw text using the intersected clipping box...
+      // (this sets the clipping internally)
+      draw_text(X, Y, W, H);
+    } else {
+      // Draw the whole area...
+      draw_text(text_area.x, text_area.y, text_area.w, text_area.h);
+    }
+  }
+  else if (damage() & FL_DAMAGE_SCROLL) {
+    // draw some lines of text
+    fl_push_clip(text_area.x, text_area.y,
+                 text_area.w, text_area.h);
+    //printf("drawing text from %d to %d\n", damage_range1_start, damage_range1_end);
+    draw_range(damage_range1_start, damage_range1_end);
+    if (damage_range2_end != -1) {
+      //printf("drawing text from %d to %d\n", damage_range2_start, damage_range2_end);
+      draw_range(damage_range2_start, damage_range2_end);
+    }
+    damage_range1_start = damage_range1_end = -1;
+    damage_range2_start = damage_range2_end = -1;
+    fl_pop_clip();
+  }
+  
+  // draw the text cursor
+  if (damage() & (FL_DAMAGE_ALL | FL_DAMAGE_SCROLL | FL_DAMAGE_EXPOSE)
+      && !buffer()->primary_selection()->selected() &&
+      mCursorOn && Fl::focus() == (Fl_Widget*)this ) {
+    fl_push_clip(text_area.x-LEFT_MARGIN,
+                 text_area.y,
+                 text_area.w+LEFT_MARGIN+RIGHT_MARGIN,
+                 text_area.h);
+    
+    int X, Y;
+    if (position_to_xy(mCursorPos, &X, &Y)) draw_cursor(X, Y);
+    //    else puts("position_to_xy() failed - unable to draw cursor!");
+    //printf("drew cursor at pos: %d (%d,%d)\n", mCursorPos, X, Y);
+    mCursorOldY = Y;
+    fl_pop_clip();
+  }
+  fl_pop_clip();
+}
+
+
+
+// this processes drag events due to mouse for Fl_Text_Display and
+// also drags due to cursor movement with shift held down for
+// Fl_Text_Editor
+void fl_text_drag_me(int pos, Fl_Text_Display* d) {
+  if (d->dragType == Fl_Text_Display::DRAG_CHAR) {
+    if (pos >= d->dragPos) {
+      d->buffer()->select(d->dragPos, pos);
+    } else {
+      d->buffer()->select(pos, d->dragPos);
+    }
+    d->insert_position(pos);
+  } else if (d->dragType == Fl_Text_Display::DRAG_WORD) {
+    if (pos >= d->dragPos) {
+      d->insert_position(d->word_end(pos));
+      d->buffer()->select(d->word_start(d->dragPos), d->word_end(pos));
+    } else {
+      d->insert_position(d->word_start(pos));
+      d->buffer()->select(d->word_start(pos), d->word_end(d->dragPos));
+    }
+  } else if (d->dragType == Fl_Text_Display::DRAG_LINE) {
+    if (pos >= d->dragPos) {
+      d->insert_position(d->buffer()->line_end(pos)+1);
+      d->buffer()->select(d->buffer()->line_start(d->dragPos),
+                          d->buffer()->line_end(pos)+1);
+    } else {
+      d->insert_position(d->buffer()->line_start(pos));
+      d->buffer()->select(d->buffer()->line_start(pos),
+                          d->buffer()->line_end(d->dragPos)+1);
+    }
+  }
+}
+
+
+
+/**
+ \brief Timer callback for scroll events.
+ 
+ This timer event scrolls the text view proportionally to
+ how far the mouse pointer has left the text area. This 
+ allows for smooth scrolling without "wiggeling" the mouse.
+ */
+void Fl_Text_Display::scroll_timer_cb(void *user_data) {
+  Fl_Text_Display *w = (Fl_Text_Display*)user_data;
+  int pos;
+  switch (scroll_direction) {
+    case 1: // mouse is to the right, scroll left
+      w->scroll(w->mTopLineNum, w->mHorizOffset + scroll_amount);
+      pos = w->xy_to_position(w->text_area.x + w->text_area.w, scroll_y, CURSOR_POS);
+      break;
+    case 2: // mouse is to the left, scroll right
+      w->scroll(w->mTopLineNum, w->mHorizOffset + scroll_amount);
+      pos = w->xy_to_position(w->text_area.x, scroll_y, CURSOR_POS);
+      break;
+    case 3: // mouse is above, scroll down
+      w->scroll(w->mTopLineNum + scroll_amount, w->mHorizOffset);
+      pos = w->xy_to_position(scroll_x, w->text_area.y, CURSOR_POS);
+      break;
+    case 4: // mouse is below, scroll up
+      w->scroll(w->mTopLineNum + scroll_amount, w->mHorizOffset);
+      pos = w->xy_to_position(scroll_x, w->text_area.y + w->text_area.h, CURSOR_POS);
+      break;
+    default:
+      return;
+  }
+  fl_text_drag_me(pos, w);
+  Fl::repeat_timeout(.1, scroll_timer_cb, user_data);
+}
+
+
+
+/**
+ \brief Event handling.
+ */
+int Fl_Text_Display::handle(int event) {
+  if (!buffer()) return 0;
+  // This isn't very elegant!
+  if (!Fl::event_inside(text_area.x, text_area.y, text_area.w, text_area.h) &&
+      !dragging && event != FL_LEAVE && event != FL_ENTER &&
+      event != FL_MOVE && event != FL_FOCUS && event != FL_UNFOCUS &&
+      event != FL_KEYBOARD && event != FL_KEYUP) {
+    return Fl_Group::handle(event);
+  }
+  
+  switch (event) {
+    case FL_ENTER:
+    case FL_MOVE:
+      if (active_r()) {
+        if (Fl::event_inside(text_area.x, text_area.y, text_area.w,
+	                     text_area.h)) window()->cursor(FL_CURSOR_INSERT);
+	else window()->cursor(FL_CURSOR_DEFAULT);
+	return 1;
+      } else {
+        return 0;
+      }
+      
+    case FL_LEAVE:
+    case FL_HIDE:
+      if (active_r() && window()) {
+        window()->cursor(FL_CURSOR_DEFAULT);
+        
+	return 1;
+      } else {
+	return 0;
+      }
+      
+    case FL_PUSH: {
+      if (active_r() && window()) {
+        if (Fl::event_inside(text_area.x, text_area.y, text_area.w,
+                             text_area.h)) window()->cursor(FL_CURSOR_INSERT);
+        else window()->cursor(FL_CURSOR_DEFAULT);
+      }
+      
+      if (Fl::focus() != this) {
+        Fl::focus(this);
+        handle(FL_FOCUS);
+      }
+      if (Fl_Group::handle(event)) return 1;
+      if (Fl::event_state()&FL_SHIFT) return handle(FL_DRAG);
+      dragging = 1;
+      int pos = xy_to_position(Fl::event_x(), Fl::event_y(), CURSOR_POS);
+      dragPos = pos;
+      if (buffer()->primary_selection()->includes(pos)) {
+        dragType = DRAG_START_DND;
+        return 1;
+      }
+      dragType = Fl::event_clicks();
+      if (dragType == DRAG_CHAR) {
+        buffer()->unselect();
+//	Fl::copy("", 0, 0); /* removed for STR 2668 */
+      }
+      else if (dragType == DRAG_WORD) {
+        buffer()->select(word_start(pos), word_end(pos));
+	dragPos = word_start(pos);
+	}
+      
+      if (buffer()->primary_selection()->selected())
+        insert_position(buffer()->primary_selection()->end());
+      else
+        insert_position(pos);
+      show_insert_position();
+      return 1;
+    }
+      
+    case FL_DRAG: {
+      if (dragType==DRAG_NONE)
+        return 1;
+      if (dragType==DRAG_START_DND) {
+        if (!Fl::event_is_click() && Fl::dnd_text_ops()) {
+          const char* copy = buffer()->selection_text();
+          Fl::dnd();
+          free((void*)copy);
+        }
+        return 1;
+      }
+      int X = Fl::event_x(), Y = Fl::event_y(), pos = insert_position();
+      // if we leave the text_area, we start a timer event
+      // that will take care of scrolling and selecting
+      if (Y < text_area.y) {
+        scroll_x = X;
+        scroll_amount = (Y - text_area.y) / 5 - 1;
+        if (!scroll_direction) {
+          Fl::add_timeout(.01, scroll_timer_cb, this);
+        }
+        scroll_direction = 3;
+      } else if (Y >= text_area.y+text_area.h) {
+        scroll_x = X;
+        scroll_amount = (Y - text_area.y - text_area.h) / 5 + 1;
+        if (!scroll_direction) {
+          Fl::add_timeout(.01, scroll_timer_cb, this);
+        }
+        scroll_direction = 4;
+      } else if (X < text_area.x) {
+        scroll_y = Y;
+        scroll_amount = (X - text_area.x) / 2 - 1;
+        if (!scroll_direction) {
+          Fl::add_timeout(.01, scroll_timer_cb, this);
+        }
+        scroll_direction = 2;
+      } else if (X >= text_area.x+text_area.w) {
+        scroll_y = Y;
+        scroll_amount = (X - text_area.x - text_area.w) / 2 + 1;
+        if (!scroll_direction) {
+          Fl::add_timeout(.01, scroll_timer_cb, this);
+        }
+        scroll_direction = 1;
+      } else {
+        if (scroll_direction) {
+          Fl::remove_timeout(scroll_timer_cb, this);
+          scroll_direction = 0;
+        }
+        pos = xy_to_position(X, Y, CURSOR_POS);
+        pos = buffer()->next_char(pos);
+      }
+      fl_text_drag_me(pos, this);
+      return 1;
+    }
+      
+    case FL_RELEASE: {
+      if (Fl::event_is_click() && (! Fl::event_clicks()) && 
+	  buffer()->primary_selection()->includes(dragPos) && !(Fl::event_state()&FL_SHIFT) ) {
+	buffer()->unselect(); // clicking in the selection: unselect and move cursor
+	insert_position(dragPos);
+	return 1;
+      } else if (Fl::event_clicks() == DRAG_LINE && Fl::event_button() == FL_LEFT_MOUSE) {
+        buffer()->select(buffer()->line_start(dragPos), buffer()->next_char(buffer()->line_end(dragPos)));
+	dragPos = line_start(dragPos);
+	dragType = DRAG_CHAR;
+      } else {
+	dragging = 0;
+	if (scroll_direction) {
+	  Fl::remove_timeout(scroll_timer_cb, this);
+	  scroll_direction = 0;
+	}
+	
+	// convert from WORD or LINE selection to CHAR
+	/*if (insert_position() >= dragPos)
+	  dragPos = buffer()->primary_selection()->start();
+	else
+	  dragPos = buffer()->primary_selection()->end();*/
+	dragType = DRAG_CHAR;
+      }
+      
+      const char* copy = buffer()->selection_text();
+      if (*copy) Fl::copy(copy, strlen(copy), 0);
+      free((void*)copy);
+      return 1;
+    }
+      
+    case FL_MOUSEWHEEL:
+      if (Fl::event_dy()) return mVScrollBar->handle(event);
+      else return mHScrollBar->handle(event);
+      
+    case FL_UNFOCUS:
+      if (active_r() && window()) window()->cursor(FL_CURSOR_DEFAULT);
+    case FL_FOCUS:
+      if (buffer()->selected()) {
+        int start, end;
+        if (buffer()->selection_position(&start, &end))
+          redisplay_range(start, end);
+      }
+      if (buffer()->secondary_selected()) {
+        int start, end;
+        if (buffer()->secondary_selection_position(&start, &end))
+          redisplay_range(start, end);
+      }
+      if (buffer()->highlight()) {
+        int start, end;
+        if (buffer()->highlight_position(&start, &end))
+          redisplay_range(start, end);
+      }
+      return 1;
+      
+    case FL_KEYBOARD:
+      // Copy?
+      if ((Fl::event_state()&(FL_CTRL|FL_COMMAND)) && Fl::event_key()=='c') {
+        if (!buffer()->selected()) return 1;
+        const char *copy = buffer()->selection_text();
+        if (*copy) Fl::copy(copy, strlen(copy), 1);
+        free((void*)copy);
+        return 1;
+      }
+      
+      // Select all ?
+      if ((Fl::event_state()&(FL_CTRL|FL_COMMAND)) && Fl::event_key()=='a') {
+        buffer()->select(0,buffer()->length());
+        const char *copy = buffer()->selection_text();
+        if (*copy) Fl::copy(copy, strlen(copy), 0);
+        free((void*)copy);
+        return 1;
+      }
+      
+      if (mVScrollBar->handle(event)) return 1;
+      if (mHScrollBar->handle(event)) return 1;
+      
+      break;
+      
+    case FL_SHORTCUT:
+      if (!(shortcut() ? Fl::test_shortcut(shortcut()) : test_shortcut()))
+        return 0;
+      if (Fl::visible_focus() && handle(FL_FOCUS)) {
+        Fl::focus(this);
+        return 1;
+      }
+      break;
+      
+  }
+  
+  return 0;
+}
+
+
+/*
+ Convert an x pixel position into a column number.
+ */
+double Fl_Text_Display::x_to_col(double y) const
+{
+  if (!mColumnScale) {
+    mColumnScale = string_width("Mitg", 4, 'A') / 4.0;
+  }
+  return (y/mColumnScale)+0.5;
+}
+
+
+/**
+ Convert a column number into an x pixel position.
+ */
+double Fl_Text_Display::col_to_x(double col) const
+{
+  if (!mColumnScale) {
+    // recalculate column scale value
+    x_to_col(0); 
+  }
+  return col*mColumnScale;
+}
+
+
+
+
+//
+// End of "$Id: Fl_Text_Display.cxx 8808 2011-06-16 13:31:25Z manolo $".
+//