commit 9492fabadbae0b06a889b3604b4249e4cf9c7a45
author Josh Gargus <jjosh@google.com> Tue Apr 17 19:13:08 2012 -0700
committer Josh Gargus <jjosh@google.com> Wed Apr 18 10:52:34 2012 -0700
tree 10ce9dca063d7242fa434cfde49615127f1e9eeb
parent 49ea2d297269d80ca3a02fc05480a1276ccf294e

Dragging CarouselTab now moves ViewPager at correct speed.

Workaround for framework bug which calls onScrollChanged() twice,
causing the ViewPager to move twice as fast as it should.

Bug: 6354327
Change-Id: I4cb1df9523373628609fadcd98c279cbe6a47c0f

src/com/android/contacts/detail/ContactDetailTabCarousel.java

diff --git a/src/com/android/contacts/detail/ContactDetailTabCarousel.java b/src/com/android/contacts/detail/ContactDetailTabCarousel.java
index 9e3a352..657a774 100644
--- a/src/com/android/contacts/detail/ContactDetailTabCarousel.java
+++ b/src/com/android/contacts/detail/ContactDetailTabCarousel.java
@@ -19,6 +19,7 @@
 import com.android.contacts.R;
 import com.android.contacts.ContactLoader;
 import com.android.contacts.detail.ContactDetailPhotoSetter;
+import com.android.contacts.util.MoreMath;
 import com.android.contacts.util.PhoneCapabilityTester;
 
 import android.content.Context;
@@ -80,8 +81,7 @@
     private int mTabDisplayLabelHeight;
 
     private boolean mScrollToCurrentTab = false;
-    private int mLastScrollPosition;
-
+    private int mLastScrollPosition = Integer.MIN_VALUE;
     private int mAllowedHorizontalScrollLength = Integer.MIN_VALUE;
     private int mAllowedVerticalScrollLength = Integer.MIN_VALUE;
 
@@ -330,24 +330,31 @@
 
     private void updateAlphaLayers() {
         float alpha = mLastScrollPosition * MAX_ALPHA / mAllowedHorizontalScrollLength;
+        alpha = MoreMath.clamp(alpha, 0.0f, 1.0f);
         mAboutTab.setAlphaLayerValue(alpha);
         mUpdatesTab.setAlphaLayerValue(MAX_ALPHA - alpha);
     }
 
     @Override
-    protected void onScrollChanged(int l, int t, int oldL, int oldT) {
-        super.onScrollChanged(l, t, oldL, oldT);
+    protected void onScrollChanged(int x, int y, int oldX, int oldY) {
+        super.onScrollChanged(x, y, oldX, oldY);
+
+        // Guard against framework issue where onScrollChanged() is called twice
+        // for each touch-move event.  This wreaked havoc on the tab-carousel: the
+        // view-pager moved twice as fast as it should because we called fakeDragBy()
+        // twice with the same value.
+        if (mLastScrollPosition == x) return;
 
         // Since we never completely scroll the about/updates tabs off-screen,
         // the draggable range is less than the width of the carousel. Our
         // listeners don't care about this... if we scroll 75% percent of our
         // draggable range, they want to scroll 75% of the entire carousel
         // width, not the same number of pixels that we scrolled.
-        int scaledL = (int) (l * mScrollScaleFactor);
-        int oldScaledL = (int) (oldL * mScrollScaleFactor);
-        mListener.onScrollChanged(scaledL, t, oldScaledL, oldT);
+        int scaledL = (int) (x * mScrollScaleFactor);
+        int oldScaledL = (int) (oldX * mScrollScaleFactor);
+        mListener.onScrollChanged(scaledL, y, oldScaledL, oldY);
 
-        mLastScrollPosition = l;
+        mLastScrollPosition = x;
         updateAlphaLayers();
     }