Add stagger and "springs" to app closing transition.

The "spring" is actually three sequential animations: 1) a slide,
2) an oscillation, and 3) a settle.

Bug: 109828964
Change-Id: I0a2c55f877446a6408952a1201636760283be57b

1 files changed, 23 insertions, 0 deletions

diff --git a/src/com/android/launcher3/anim/Interpolators.java b/src/com/android/launcher3/anim/Interpolators.java
index a4cba4f62..efb08a11a 100644
--- a/src/com/android/launcher3/anim/Interpolators.java
+++ b/src/com/android/launcher3/anim/Interpolators.java
@@ -112,6 +112,29 @@ public class Interpolators {
         }
     };
 
+    /**
+     * Interpolates using a particular section of the damped oscillation function.
+     * The section is selected by scaling and shifting the function.
+     */
+    public static final Interpolator OSCILLATE = new Interpolator() {
+
+        // Used to scale the oscillations horizontally
+        private final float horizontalScale = 1f;
+        // Used to shift the oscillations horizontally
+        private final float horizontalShift = 05f;
+        // Used to scale the oscillations vertically
+        private final float verticalScale = 1f;
+        // Used to shift the oscillations vertically
+        private final float verticalShift = 1f;
+
+        @Override
+        public float getInterpolation(float t) {
+            t = horizontalScale * (t + horizontalShift);
+            return (float) ((verticalScale * (Math.exp(-t) * Math.cos(2 * Math.PI * t)))
+                    + verticalShift);
+        }
+    };
+
     private static final float FAST_FLING_PX_MS = 10;
 
     public static Interpolator scrollInterpolatorForVelocity(float velocity) {