Polish for all apps physics.

By adjusting the start value based on the direction of the scroll,
the springs will appear more smooth.

This only changes the appearance of the spring when scrolling down,
since the start value has always been 1 and thus looked fine when
scrolling up.

Bug: 38349031
Change-Id: I563e6e7cfdbc74c4a95adb22f90d5efe17dfa453

3 files changed, 8 insertions, 4 deletions

diff --git a/src/com/android/launcher3/allapps/AllAppsContainerView.java b/src/com/android/launcher3/allapps/AllAppsContainerView.java
index 189b9358f..499eb4588 100644
--- a/src/com/android/launcher3/allapps/AllAppsContainerView.java
+++ b/src/com/android/launcher3/allapps/AllAppsContainerView.java
@@ -423,8 +423,9 @@ public class AllAppsContainerView extends BaseContainerView implements DragSourc
 
             // We only show the spring animation when at the top or bottom, so we wait until the
             // first or last row is visible to ensure that all animations run in sync.
-            if ((first == 0 && dy < 0) || (last == mAdapter.getItemCount() - 1 && dy > 0)) {
-                mSpringAnimationHandler.animateToFinalPosition(0);
+            boolean scrollUp = dy < 0;
+            if ((first == 0 && scrollUp) || (last == mAdapter.getItemCount() - 1 && dy > 0)) {
+                mSpringAnimationHandler.animateToFinalPosition(0, scrollUp ? 1 : -1);
             }
         }
 
diff --git a/src/com/android/launcher3/allapps/AllAppsRecyclerView.java b/src/com/android/launcher3/allapps/AllAppsRecyclerView.java
index a2bd43d84..34421bdac 100644
--- a/src/com/android/launcher3/allapps/AllAppsRecyclerView.java
+++ b/src/com/android/launcher3/allapps/AllAppsRecyclerView.java
@@ -511,7 +511,9 @@ public class AllAppsRecyclerView extends BaseRecyclerView {
                 if (FeatureFlags.LAUNCHER3_PHYSICS) {
                     // We calculate our own velocity to give the springs the desired effect.
                     velocity = y / getDampedOverScroll(getHeight()) * MAX_RELEASE_VELOCITY;
-                    mSpringAnimationHandler.animateToPositionWithVelocity(0, -velocity);
+                    // We want to negate the velocity because we are moving to 0 from -1 due to the
+                    // downward motion. (y-axis -1 is above 0).
+                    mSpringAnimationHandler.animateToPositionWithVelocity(0, -1, -velocity);
                 }
 
                 ObjectAnimator.ofFloat(AllAppsRecyclerView.this,
diff --git a/src/com/android/launcher3/allapps/AllAppsTransitionController.java b/src/com/android/launcher3/allapps/AllAppsTransitionController.java
index 4d112c632..0859e0658 100644
--- a/src/com/android/launcher3/allapps/AllAppsTransitionController.java
+++ b/src/com/android/launcher3/allapps/AllAppsTransitionController.java
@@ -228,7 +228,8 @@ public class AllAppsTransitionController implements TouchController, VerticalPul
                 }
                 mLauncher.showAppsView(true /* animated */, false /* updatePredictedApps */);
                 if (hasSpringAnimationHandler()) {
-                    mSpringAnimationHandler.animateToFinalPosition(0);
+                    // The icons are moving upwards, so we go to 0 from 1. (y-axis 1 is below 0.)
+                    mSpringAnimationHandler.animateToFinalPosition(0 /* pos */, 1 /* startValue */);
                 }
             } else {
                 calculateDuration(velocity, Math.abs(mShiftRange - mAppsView.getTranslationY()));