commit 51e224a121b1f42f86cc9e022f6ecc63461e61a5
author Hyunyoung Song <hyunyoungs@google.com> Fri Jul 14 13:34:55 2017 -0700
committer Hyunyoung Song <hyunyoungs@google.com> Tue Jul 18 14:59:48 2017 -0700
tree 1231decf3389d8c3367a16da7be27e90665d488c
parent 6cd0e46a8ee384a5255b6189cd46ed694fcbecac

SwipeDetector should work on multi touch finger points
Bug: 63815304
Change-Id: I66b0bedeed0bd3fadc5f2f73fd76e64010170c97

src/com/android/launcher3/touch/SwipeDetector.java

diff --git a/src/com/android/launcher3/touch/SwipeDetector.java b/src/com/android/launcher3/touch/SwipeDetector.java
index b470654..ec5493b 100644
--- a/src/com/android/launcher3/touch/SwipeDetector.java
+++ b/src/com/android/launcher3/touch/SwipeDetector.java
@@ -1,5 +1,6 @@
 package com.android.launcher3.touch;
 
+import static android.view.MotionEvent.INVALID_POINTER_ID;
 import android.content.Context;
 import android.util.Log;
 import android.view.MotionEvent;
@@ -24,6 +25,8 @@
     private static final float ANIMATION_DURATION = 1200;
     private static final float FAST_FLING_PX_MS = 10;
 
+    protected int mActivePointerId = INVALID_POINTER_ID;
+
     /**
      * The minimum release velocity in pixels per millisecond that triggers fling..
      */
@@ -97,7 +100,8 @@
     private long mCurrentMillis;
 
     private float mVelocity;
-    private float mLastDisplacement;
+    private float mLastDisplacementX;
+    private float mLastDisplacementY;
     private float mDisplacementY;
     private float mDisplacementX;
 
@@ -149,11 +153,13 @@
     }
 
     public boolean onTouchEvent(MotionEvent ev) {
-        switch (ev.getAction()) {
+        switch (ev.getActionMasked()) {
             case MotionEvent.ACTION_DOWN:
                 mDownX = ev.getX();
                 mDownY = ev.getY();
-                mLastDisplacement = 0;
+                mActivePointerId = ev.getPointerId(0);
+                mLastDisplacementX = 0;
+                mLastDisplacementY = 0;
                 mDisplacementY = 0;
                 mVelocity = 0;
 
@@ -161,9 +167,26 @@
                     setState(ScrollState.DRAGGING);
                 }
                 break;
+            //case MotionEvent.ACTION_POINTER_DOWN:
+            case MotionEvent.ACTION_POINTER_UP:
+                int ptrIdx = (ev.getActionIndex() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
+                        MotionEvent.ACTION_POINTER_INDEX_SHIFT;
+                int ptrId = ev.getPointerId(ptrIdx);
+                if (ptrId == mActivePointerId) {
+                    final int newPointerIdx = ptrIdx == 0 ? 1 : 0;
+                    mDownX = ev.getX(newPointerIdx) - mLastDisplacementX;
+                    mDownY = ev.getY(newPointerIdx) - mLastDisplacementY;
+                    mActivePointerId = ev.getPointerId(newPointerIdx);
+                }
+                break;
             case MotionEvent.ACTION_MOVE:
-                mDisplacementX = ev.getX() - mDownX;
-                mDisplacementY = ev.getY() - mDownY;
+                int pointerIndex = ev.findPointerIndex(mActivePointerId);
+                if (pointerIndex == INVALID_POINTER_ID) {
+                    break;
+                }
+                mDisplacementX = ev.getX(pointerIndex) - mDownX;
+                mDisplacementY = ev.getY(pointerIndex) - mDownY;
+
                 computeVelocity(ev);
 
                 // handle state and listener calls.
@@ -186,8 +209,12 @@
                 break;
         }
         // Do house keeping.
-        mLastDisplacement = mDisplacementY;
-        mLastY = ev.getY();
+        mLastDisplacementX = mDisplacementX;
+        mLastDisplacementY = mDisplacementY;
+        int pointerIndex = ev.findPointerIndex(mActivePointerId);
+        if (pointerIndex != INVALID_POINTER_ID) {
+            mLastY = ev.getY(pointerIndex);
+        }
         return true;
     }
 
@@ -215,7 +242,7 @@
     }
 
     private boolean reportDragging() {
-        float delta = mDisplacementY - mLastDisplacement;
+        float delta = mDisplacementY - mLastDisplacementY;
         if (delta != 0) {
             if (DBG) {
                 Log.d(TAG, String.format("onDrag disp=%.1f, velocity=%.1f",