From 390120b925398c754b4f785fc12a8def0d09c09b Mon Sep 17 00:00:00 2001
From: Michael Kwan <mkwan@google.com>
Date: Tue, 14 Feb 2017 12:04:38 -0800
Subject: [PATCH] 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
---
 .../internal/widget/SwipeDismissLayout.java     | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/core/java/com/android/internal/widget/SwipeDismissLayout.java b/core/java/com/android/internal/widget/SwipeDismissLayout.java
index 261fa43274948..6d814bf14bc0a 100644
--- a/core/java/com/android/internal/widget/SwipeDismissLayout.java
+++ b/core/java/com/android/internal/widget/SwipeDismissLayout.java
@@ -79,7 +79,6 @@ public class SwipeDismissLayout extends FrameLayout {
     private boolean mDismissed;
     private boolean mDiscardIntercept;
     private VelocityTracker mVelocityTracker;
-    private float mTranslationX;
     private boolean mBlockGesture = false;
     private boolean mActivityTranslucencyConverted = false;
 
@@ -166,8 +165,10 @@ public class SwipeDismissLayout extends FrameLayout {
             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 @@ public class SwipeDismissLayout extends FrameLayout {
         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 @@ public class SwipeDismissLayout extends FrameLayout {
     }
 
     private void setProgress(float deltaX) {
-        mTranslationX = deltaX;
         if (mProgressListener != null && deltaX >= 0)  {
             mProgressListener.onSwipeProgressChanged(
                     this, progressToAlpha(deltaX / getWidth()), deltaX);
@@ -300,7 +304,6 @@ public class SwipeDismissLayout extends FrameLayout {
             mVelocityTracker.recycle();
         }
         mVelocityTracker = null;
-        mTranslationX = 0;
         mDownX = 0;
         mLastX = Integer.MIN_VALUE;
         mDownY = 0;