src/com/android/launcher3/ButtonDropTarget.java

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.launcher3;

import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.graphics.PointF;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.TransitionDrawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.LinearInterpolator;
import android.widget.TextView;

import com.android.launcher3.util.Thunk;

/**
 * Implements a DropTarget.
 */
public abstract class ButtonDropTarget extends TextView
        implements DropTarget, DragController.DragListener, OnClickListener {

    private static int DRAG_VIEW_DROP_DURATION = 285;

    protected final int mTransitionDuration;

    protected Launcher mLauncher;
    private int mBottomDragPadding;
    protected TextView mText;
    protected SearchDropTargetBar mSearchDropTargetBar;

    /** Whether this drop target is active for the current drag */
    protected boolean mActive;

    /** The paint applied to the drag view on hover */
    protected int mHoverColor = 0;

    protected ColorStateList mOriginalTextColor;
    protected TransitionDrawable mDrawable;

    public ButtonDropTarget(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ButtonDropTarget(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        Resources r = getResources();
        mTransitionDuration = r.getInteger(R.integer.config_dropTargetBgTransitionDuration);
        mBottomDragPadding = r.getDimensionPixelSize(R.dimen.drop_target_drag_padding);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        mOriginalTextColor = getTextColors();

        // Remove the text in the Phone UI in landscape
        int orientation = getResources().getConfiguration().orientation;
        if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
            if (!LauncherAppState.getInstance().isScreenLarge()) {
                setText("");
            }
        }
    }

    protected void setDrawable(int resId) {
        // Get the hover color
        mDrawable = (TransitionDrawable) getCurrentDrawable();

        if (mDrawable == null) {
            // TODO: investigate why this is ever happening. Presently only on one known device.
            mDrawable = (TransitionDrawable) getResources().getDrawable(resId);
            setCompoundDrawablesRelativeWithIntrinsicBounds(mDrawable, null, null, null);
        }

        if (null != mDrawable) {
            mDrawable.setCrossFadeEnabled(true);
        }
    }

    public void setLauncher(Launcher launcher) {
        mLauncher = launcher;
    }

    public void setSearchDropTargetBar(SearchDropTargetBar searchDropTargetBar) {
        mSearchDropTargetBar = searchDropTargetBar;
    }

    protected Drawable getCurrentDrawable() {
        Drawable[] drawables = getCompoundDrawablesRelative();
        for (int i = 0; i < drawables.length; ++i) {
            if (drawables[i] != null) {
                return drawables[i];
            }
        }
        return null;
    }

    @Override
    public void onFlingToDelete(DragObject d, int x, int y, PointF vec) { }

    @Override
    public final void onDragEnter(DragObject d) {
        d.dragView.setColor(mHoverColor);
        mDrawable.startTransition(mTransitionDuration);
        setTextColor(mHoverColor);
    }

    @Override
    public void onDragOver(DragObject d) {
        // Do nothing
    }

    protected void resetHoverColor() {
        mDrawable.resetTransition();
        setTextColor(mOriginalTextColor);
    }

    @Override
    public final void onDragExit(DragObject d) {
        if (!d.dragComplete) {
            d.dragView.setColor(0);
            resetHoverColor();
        } else {
            // Restore the hover color
            d.dragView.setColor(mHoverColor);
        }
    }

    @Override
    public final void onDragStart(DragSource source, Object info, int dragAction) {
        mActive = supportsDrop(source, info);
        mDrawable.resetTransition();
        setTextColor(mOriginalTextColor);
        ((ViewGroup) getParent()).setVisibility(mActive ? View.VISIBLE : View.GONE);
    }

    @Override
    public final boolean acceptDrop(DragObject dragObject) {
        return supportsDrop(dragObject.dragSource, dragObject.dragInfo);
    }

    protected abstract boolean supportsDrop(DragSource source, Object info);

    @Override
    public boolean isDropEnabled() {
        return mActive;
    }

    @Override
    public void onDragEnd() {
        mActive = false;
    }

    /**
     * On drop animate the dropView to the icon.
     */
    @Override
    public void onDrop(final DragObject d) {
        final DragLayer dragLayer = mLauncher.getDragLayer();
        final Rect from = new Rect();
        dragLayer.getViewRectRelativeToSelf(d.dragView, from);

        int width = mDrawable.getIntrinsicWidth();
        int height = mDrawable.getIntrinsicHeight();
        final Rect to = getIconRect(d.dragView.getMeasuredWidth(), d.dragView.getMeasuredHeight(),
                width, height);
        final float scale = (float) to.width() / from.width();
        mSearchDropTargetBar.deferOnDragEnd();

        Runnable onAnimationEndRunnable = new Runnable() {
            @Override
            public void run() {
                completeDrop(d);
                mSearchDropTargetBar.onDragEnd();
                mLauncher.exitSpringLoadedDragModeDelayed(true, 0, null);
            }
        };
        dragLayer.animateView(d.dragView, from, to, scale, 1f, 1f, 0.1f, 0.1f,
                DRAG_VIEW_DROP_DURATION, new DecelerateInterpolator(2),
                new LinearInterpolator(), onAnimationEndRunnable,
                DragLayer.ANIMATION_END_DISAPPEAR, null);
    }

    @Override
    public void prepareAccessibilityDrop() { }

    @Thunk abstract void completeDrop(DragObject d);

    @Override
    public void getHitRectRelativeToDragLayer(android.graphics.Rect outRect) {
        super.getHitRect(outRect);
        outRect.bottom += mBottomDragPadding;

        int[] coords = new int[2];
        mLauncher.getDragLayer().getDescendantCoordRelativeToSelf(this, coords);
        outRect.offsetTo(coords[0], coords[1]);
    }

    private boolean isRtl() {
        return (getLayoutDirection() == LAYOUT_DIRECTION_RTL);
    }

    protected Rect getIconRect(int viewWidth, int viewHeight, int drawableWidth, int drawableHeight) {
        DragLayer dragLayer = mLauncher.getDragLayer();

        // Find the rect to animate to (the view is center aligned)
        Rect to = new Rect();
        dragLayer.getViewRectRelativeToSelf(this, to);

        final int width = drawableWidth;
        final int height = drawableHeight;

        final int left;
        final int right;

        if (isRtl()) {
            right = to.right - getPaddingRight();
            left = right - width;
        } else {
            left = to.left + getPaddingLeft();
            right = left + width;
        }

        final int top = to.top + (getMeasuredHeight() - height) / 2;
        final int bottom = top +  height;

        to.set(left, top, right, bottom);

        // Center the destination rect about the trash icon
        final int xOffset = (int) -(viewWidth - width) / 2;
        final int yOffset = (int) -(viewHeight - height) / 2;
        to.offset(xOffset, yOffset);

        return to;
    }

    @Override
    public void getLocationInDragLayer(int[] loc) {
        mLauncher.getDragLayer().getLocationInDragLayer(this, loc);
    }

    public void enableAccessibleDrag(boolean enable) {
        setOnClickListener(enable ? this : null);
    }

    protected String getAccessibilityDropConfirmation() {
        return null;
    }

    @Override
    public void onClick(View v) {
        LauncherAppState.getInstance().getAccessibilityDelegate()
            .handleAccessibleDrop(this, null, getAccessibilityDropConfirmation());
    }
}