2 files changed, 69 insertions, 0 deletions
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/back/TouchTracker.java b/libs/WindowManager/Shell/src/com/android/wm/shell/back/TouchTracker.java
index 6213f628dfd3..8f04f126960c 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/back/TouchTracker.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/back/TouchTracker.java
@@ -63,6 +63,10 @@ class TouchTracker {
         if ((touchX < mStartThresholdX && mSwipeEdge == BackEvent.EDGE_LEFT)
                 || (touchX > mStartThresholdX && mSwipeEdge == BackEvent.EDGE_RIGHT)) {
             mStartThresholdX = touchX;
+            if ((mSwipeEdge == BackEvent.EDGE_LEFT && mStartThresholdX < mInitTouchX)
+                    || (mSwipeEdge == BackEvent.EDGE_RIGHT && mStartThresholdX > mInitTouchX)) {
+                mInitTouchX = mStartThresholdX;
+            }
         }
         mLatestTouchX = touchX;
         mLatestTouchY = touchY;
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/TouchTrackerTest.kt b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/TouchTrackerTest.kt
index bf07dccd0658..6dbb1e2b8d92 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/TouchTrackerTest.kt
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/TouchTrackerTest.kt
@@ -170,6 +170,71 @@ class TouchTrackerTest {
         nonLinearTracker.assertProgress((touchX - INITIAL_X_LEFT_EDGE) / nonLinearTarget)
     }
 
+    @Test
+    fun restartingGesture_resetsInitialTouchX_leftEdge() {
+        val linearTracker = linearTouchTracker()
+        linearTracker.setGestureStartLocation(INITIAL_X_LEFT_EDGE, 0f, BackEvent.EDGE_LEFT)
+        var touchX = 100f
+        val velocityX = 0f
+        val velocityY = 0f
+
+        // assert that progress is increased when increasing touchX
+        linearTracker.update(touchX, 0f, velocityX, velocityY)
+        linearTracker.assertProgress((touchX - INITIAL_X_LEFT_EDGE) / MAX_DISTANCE)
+
+        // assert that progress is reset to 0 when start location is updated
+        linearTracker.updateStartLocation()
+        linearTracker.assertProgress(0f)
+
+        // assert that progress remains 0 when touchX is decreased
+        touchX -= 50
+        linearTracker.update(touchX, 0f, velocityX, velocityY)
+        linearTracker.assertProgress(0f)
+
+        // assert that progress uses new minimal touchX for progress calculation
+        val newInitialTouchX = touchX
+        touchX += 100
+        linearTracker.update(touchX, 0f, velocityX, velocityY)
+        linearTracker.assertProgress((touchX - newInitialTouchX) / MAX_DISTANCE)
+
+        // assert the same for triggerBack==true
+        linearTracker.triggerBack = true
+        linearTracker.assertProgress((touchX - newInitialTouchX) / MAX_DISTANCE)
+    }
+
+    @Test
+    fun restartingGesture_resetsInitialTouchX_rightEdge() {
+        val linearTracker = linearTouchTracker()
+        linearTracker.setGestureStartLocation(INITIAL_X_RIGHT_EDGE, 0f, BackEvent.EDGE_RIGHT)
+
+        var touchX = INITIAL_X_RIGHT_EDGE - 100f
+        val velocityX = 0f
+        val velocityY = 0f
+
+        // assert that progress is increased when decreasing touchX
+        linearTracker.update(touchX, 0f, velocityX, velocityY)
+        linearTracker.assertProgress((INITIAL_X_RIGHT_EDGE - touchX) / MAX_DISTANCE)
+
+        // assert that progress is reset to 0 when start location is updated
+        linearTracker.updateStartLocation()
+        linearTracker.assertProgress(0f)
+
+        // assert that progress remains 0 when touchX is increased
+        touchX += 50
+        linearTracker.update(touchX, 0f, velocityX, velocityY)
+        linearTracker.assertProgress(0f)
+
+        // assert that progress uses new maximal touchX for progress calculation
+        val newInitialTouchX = touchX
+        touchX -= 100
+        linearTracker.update(touchX, 0f, velocityX, velocityY)
+        linearTracker.assertProgress((newInitialTouchX - touchX) / MAX_DISTANCE)
+
+        // assert the same for triggerBack==true
+        linearTracker.triggerBack = true
+        linearTracker.assertProgress((newInitialTouchX - touchX) / MAX_DISTANCE)
+    }
+
     companion object {
         private const val MAX_DISTANCE = 500f
         private const val LINEAR_DISTANCE = 400f