commit 390120b925398c754b4f785fc12a8def0d09c09b
author Michael Kwan <mkwan@google.com> Tue Feb 14 12:04:38 2017 -0800
committer Michael Kwan <mkwan@google.com> Tue Feb 14 12:04:38 2017 -0800
tree a7b665f3e49f81fecd55b0679c470a58294f17a4
parent 5758a9a94c7ca1a196b3d1c51b05ec2d937f0b59

Fix incorrect values for VelocityTracker in SwipeDismissLayout.

The offset used to adjust MotionEvents for swipe velocity tracking
was incorrect, and caused issues when touch points where close
together. Fixed the offset used, which resolved swiping issues.

Bug: 34673753
Change-Id: Ide6060b511510bcf299e3db778e6ffc6afda5e19

core/java/com/android/internal/widget/SwipeDismissLayout.java

diff --git a/core/java/com/android/internal/widget/SwipeDismissLayout.java b/core/java/com/android/internal/widget/SwipeDismissLayout.java
index 261fa43..6d814bf 100644
--- a/core/java/com/android/internal/widget/SwipeDismissLayout.java
+++ b/core/java/com/android/internal/widget/SwipeDismissLayout.java
@@ -79,7 +79,6 @@
     private boolean mDismissed;
     private boolean mDiscardIntercept;
     private VelocityTracker mVelocityTracker;
-    private float mTranslationX;
     private boolean mBlockGesture = false;
     private boolean mActivityTranslucencyConverted = false;
 
@@ -166,8 +165,10 @@
             return super.onInterceptTouchEvent(ev);
         }
 
-        // offset because the view is translated during swipe
-        ev.offsetLocation(mTranslationX, 0);
+        // Offset because the view is translated during swipe, match X with raw X. Active touch
+        // coordinates are mostly used by the velocity tracker, so offset it to match the raw
+        // coordinates which is what is primarily used elsewhere.
+        ev.offsetLocation(ev.getRawX() - ev.getX(), 0);
 
         switch (ev.getActionMasked()) {
             case MotionEvent.ACTION_DOWN:
@@ -232,8 +233,12 @@
         if (mVelocityTracker == null || !mDismissable) {
             return super.onTouchEvent(ev);
         }
-        // offset because the view is translated during swipe
-        ev.offsetLocation(mTranslationX, 0);
+
+        // Offset because the view is translated during swipe, match X with raw X. Active touch
+        // coordinates are mostly used by the velocity tracker, so offset it to match the raw
+        // coordinates which is what is primarily used elsewhere.
+        ev.offsetLocation(ev.getRawX() - ev.getX(), 0);
+
         switch (ev.getActionMasked()) {
             case MotionEvent.ACTION_UP:
                 updateDismiss(ev);
@@ -266,7 +271,6 @@
     }
 
     private void setProgress(float deltaX) {
-        mTranslationX = deltaX;
         if (mProgressListener != null && deltaX >= 0)  {
             mProgressListener.onSwipeProgressChanged(
                     this, progressToAlpha(deltaX / getWidth()), deltaX);
@@ -300,7 +304,6 @@
             mVelocityTracker.recycle();
         }
         mVelocityTracker = null;
-        mTranslationX = 0;
         mDownX = 0;
         mLastX = Integer.MIN_VALUE;
         mDownY = 0;