From 6dfed24158b8fc9150abee23992db621cd82aa43 Mon Sep 17 00:00:00 2001
From: Romain Guy <romainguy@android.com>
Date: Mon, 11 May 2009 18:25:05 -0700
Subject: [PATCH] Fixes 1844680. Interrupted scrolling could lead to rendering
 artifacts. The ListView was invalidating itself in opaque mode but before the
 drawing could happen, it was getting rid of its scrolling cache, thus
 becoming translucent again.

---
 core/java/android/widget/AbsListView.java | 40 ++++++++++++++---------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/core/java/android/widget/AbsListView.java b/core/java/android/widget/AbsListView.java
index ffb6785dca275..4f503b4884603 100644
--- a/core/java/android/widget/AbsListView.java
+++ b/core/java/android/widget/AbsListView.java
@@ -433,7 +433,9 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
 
     private InputConnection mDefInputConnection;
     private InputConnectionWrapper mPublicInputConnection;
-    
+
+    private Runnable mClearScrollingCache;
+
     /**
      * Interface definition for a callback to be invoked when the list or grid
      * has been scrolled.
@@ -1947,7 +1949,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
                 if (y != mLastY) {
                     deltaY -= mMotionCorrection;
                     int incrementalDeltaY = mLastY != Integer.MIN_VALUE ? y - mLastY : deltaY;
-                    trackMotionScroll(deltaY, incrementalDeltaY, true);
+                    trackMotionScroll(deltaY, incrementalDeltaY);
 
                     // Check to see if we have bumped into the scroll limit
                     View motionView = this.getChildAt(mMotionPosition - mFirstPosition);
@@ -2286,7 +2288,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
                 delta = Math.max(-(getHeight() - mPaddingBottom - mPaddingTop - 1), delta);
             }
 
-            trackMotionScroll(delta, delta, false);
+            trackMotionScroll(delta, delta);
 
             // Check to see if we have bumped into the scroll limit
             View motionView = getChildAt(mMotionPosition - mFirstPosition);
@@ -2323,16 +2325,23 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
     }
 
     private void clearScrollingCache() {
-        if (mCachingStarted) {
-            mCachingStarted = false;
-            setChildrenDrawnWithCacheEnabled(false);
-            if ((mPersistentDrawingCache & PERSISTENT_SCROLLING_CACHE) == 0) {
-                setChildrenDrawingCacheEnabled(false);
-            }
-            if (!isAlwaysDrawnWithCacheEnabled()) {
-                invalidate();
-            }
+        if (mClearScrollingCache == null) {
+            mClearScrollingCache = new Runnable() {
+                public void run() {
+                    if (mCachingStarted) {
+                        mCachingStarted = false;
+                        setChildrenDrawnWithCacheEnabled(false);
+                        if ((mPersistentDrawingCache & PERSISTENT_SCROLLING_CACHE) == 0) {
+                            setChildrenDrawingCacheEnabled(false);
+                        }
+                        if (!isAlwaysDrawnWithCacheEnabled()) {
+                            invalidate();
+                        }
+                    }
+                }
+            };
         }
+        post(mClearScrollingCache);
     }
 
     /**
@@ -2341,9 +2350,8 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
      * @param deltaY Amount to offset mMotionView. This is the accumulated delta since the motion
      *        began. Positive numbers mean the user's finger is moving down the screen.
      * @param incrementalDeltaY Change in deltaY from the previous event.
-     * @param invalidate True to make this method call invalidate(), false otherwise.
      */
-    void trackMotionScroll(int deltaY, int incrementalDeltaY, boolean invalidate) {
+    void trackMotionScroll(int deltaY, int incrementalDeltaY) {
         final int childCount = getChildCount();
         if (childCount == 0) {
             return;
@@ -2377,7 +2385,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
         if (spaceAbove >= absIncrementalDeltaY && spaceBelow >= absIncrementalDeltaY) {
             hideSelector();
             offsetChildrenTopAndBottom(incrementalDeltaY);
-            if (invalidate) invalidate();
+            invalidate();
             mMotionViewNewTop = mMotionViewOriginalTop + deltaY;
         } else {
             final int firstPosition = mFirstPosition;
@@ -2455,7 +2463,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
                 mFirstPosition += count;
             }
 
-            if (invalidate) invalidate();
+            invalidate();
             fillGap(down);
             mBlockLayoutRequests = false;