Subtracting the touchSlop when dragging the window, to prevent initial jump

Change-Id: I26a79076312d4641693a9610c17cf925d5d104ea
diff --git a/quickstep/src/com/android/quickstep/NavBarSwipeInteractionHandler.java b/quickstep/src/com/android/quickstep/NavBarSwipeInteractionHandler.java
index e03a2ff..102f859 100644
--- a/quickstep/src/com/android/quickstep/NavBarSwipeInteractionHandler.java
+++ b/quickstep/src/com/android/quickstep/NavBarSwipeInteractionHandler.java
@@ -61,7 +61,8 @@
 
     private static final long RECENTS_VIEW_VISIBILITY_DELAY = 120;
     private static final long RECENTS_VIEW_VISIBILITY_DURATION = 150;
-    private static final long DEFAULT_SWIPE_DURATION = 200;
+    private static final long MAX_SWIPE_DURATION = 200;
+    private static final long MIN_SWIPE_DURATION = 80;
 
     // Ideal velocity for a smooth transition
     private static final float PIXEL_PER_MS = 2f;
@@ -127,8 +128,8 @@
         new Handler().postDelayed(() -> mStateCallback.setState(STATE_RECENTS_DELAY_COMPLETE),
                 RECENTS_VIEW_VISIBILITY_DELAY);
 
-        long duration = Math.min(DEFAULT_SWIPE_DURATION,
-                Math.max((long) (-mCurrentDisplacement / PIXEL_PER_MS), 0));
+        long duration = Math.min(MAX_SWIPE_DURATION,
+                Math.max((long) (-mCurrentDisplacement / PIXEL_PER_MS), MIN_SWIPE_DURATION));
         if (mCurrentShift.getCurrentAnimation() != null) {
             ObjectAnimator anim = mCurrentShift.getCurrentAnimation();
             long theirDuration = anim.getDuration() - anim.getCurrentPlayTime();
@@ -260,7 +261,7 @@
         float flingThreshold = res.getDimension(R.dimen.quickstep_fling_threshold_velocity);
         boolean isFling = Math.abs(endVelocity) > flingThreshold;
 
-        long duration = DEFAULT_SWIPE_DURATION;
+        long duration = MAX_SWIPE_DURATION;
         final float endShift;
         if (!isFling) {
             endShift = mCurrentShift.value >= MIN_PROGRESS_FOR_OVERVIEW ? 1 : 0;
diff --git a/quickstep/src/com/android/quickstep/TouchInteractionService.java b/quickstep/src/com/android/quickstep/TouchInteractionService.java
index ff26fb3..b34601d 100644
--- a/quickstep/src/com/android/quickstep/TouchInteractionService.java
+++ b/quickstep/src/com/android/quickstep/TouchInteractionService.java
@@ -87,6 +87,7 @@
     private int mActivePointerId = INVALID_POINTER_ID;
     private VelocityTracker mVelocityTracker;
     private int mTouchSlop;
+    private float mStartDisplacement;
     private NavBarSwipeInteractionHandler mInteractionHandler;
 
     private ISystemUiProxy mISystemUiProxy;
@@ -183,11 +184,12 @@
                 float displacement = ev.getY(pointerIndex) - mDownPos.y;
                 if (mInteractionHandler == null) {
                     if (Math.abs(displacement) >= mTouchSlop) {
+                        mStartDisplacement = Math.signum(displacement) * mTouchSlop;
                         startTouchTracking();
                     }
                 } else {
                     // Move
-                    mInteractionHandler.updateDisplacement(displacement);
+                    mInteractionHandler.updateDisplacement(displacement - mStartDisplacement);
                 }
                 break;
             }