DO NOT MERGE Adjust amount pull effects the glow and edge decay.

Edge decay is now based on the remaining height of the glow so that
as the glow reduces, the edge will reduce and not disappear entirely
before the glow is gone.

Change-Id: I03376ee3807e21ce6ac74c0cfad713b7fd5e4520

1 files changed, 21 insertions, 9 deletions

diff --git a/core/java/android/widget/EdgeGlow.java b/core/java/android/widget/EdgeGlow.java
index 1f7daabd426a..7a990adf6ba4 100644
--- a/core/java/android/widget/EdgeGlow.java
+++ b/core/java/android/widget/EdgeGlow.java
@@ -91,6 +91,7 @@ public class EdgeGlow {
     // How much dragging should effect the height of the glow image.
     // Number determined by user testing.
     private static final int PULL_DISTANCE_GLOW_FACTOR = 5;
+    private static final float PULL_DISTANCE_ALPHA_GLOW_FACTOR = 0.8f;
 
     private static final int VELOCITY_EDGE_FACTOR = 8;
     private static final int VELOCITY_GLOW_FACTOR = 16;
@@ -144,8 +145,10 @@ public class EdgeGlow {
         mEdgeScaleY = mEdgeScaleYStart = Math.max(
                 HELD_EDGE_SCALE_Y, Math.min(distance * PULL_DISTANCE_EDGE_FACTOR, 1.f));
 
-        mGlowAlpha = mGlowAlphaStart = Math.max(
-                0.5f, Math.min(mGlowAlpha + Math.abs(deltaDistance), MAX_ALPHA));
+        mGlowAlpha = mGlowAlphaStart = Math.min(
+                mGlowAlpha +
+                (Math.abs(deltaDistance) * PULL_DISTANCE_ALPHA_GLOW_FACTOR),
+                MAX_ALPHA);
 
         float glowChange = Math.abs(deltaDistance);
         if (deltaDistance > 0 && mPullDistance < 0) {
@@ -202,8 +205,8 @@ public class EdgeGlow {
 
         // The edge should always be at least partially visible, regardless
         // of velocity.
-        mEdgeAlphaStart = 0.5f;
-        mEdgeScaleYStart = 0.2f;
+        mEdgeAlphaStart = 0.f;
+        mEdgeScaleY = mEdgeScaleYStart = 0.f;
         // The glow depends more on the velocity, and therefore starts out
         // nearly invisible.
         mGlowAlphaStart = 0.5f;
@@ -213,7 +216,8 @@ public class EdgeGlow {
         // reflect the strength of the user's scrolling.
         mEdgeAlphaFinish = Math.max(0, Math.min(velocity * VELOCITY_EDGE_FACTOR, 1));
         // Edge should never get larger than the size of its asset.
-        mEdgeScaleYFinish = 1.f;
+        mEdgeScaleYFinish = Math.max(
+                HELD_EDGE_SCALE_Y, Math.min(velocity * VELOCITY_EDGE_FACTOR, 1.f));
 
         // Growth for the size of the glow should be quadratic to properly
         // respond
@@ -281,10 +285,11 @@ public class EdgeGlow {
                     mGlowAlphaStart = mGlowAlpha;
                     mGlowScaleYStart = mGlowScaleY;
 
+                    // After absorb, the glow and edge should fade to nothing.
                     mEdgeAlphaFinish = 0.f;
-                    mEdgeScaleYFinish = mEdgeScaleY;
+                    mEdgeScaleYFinish = 0.f;
                     mGlowAlphaFinish = 0.f;
-                    mGlowScaleYFinish = mGlowScaleY;
+                    mGlowScaleYFinish = 0.f;
                     break;
                 case STATE_PULL:
                     mState = STATE_PULL_DECAY;
@@ -296,14 +301,21 @@ public class EdgeGlow {
                     mGlowAlphaStart = mGlowAlpha;
                     mGlowScaleYStart = mGlowScaleY;
 
-                    // After a pull, the glow should fade to nothing.
+                    // After pull, the glow and edge should fade to nothing.
                     mEdgeAlphaFinish = 0.f;
                     mEdgeScaleYFinish = 0.f;
                     mGlowAlphaFinish = 0.f;
                     mGlowScaleYFinish = 0.f;
                     break;
                 case STATE_PULL_DECAY:
-                    // Do nothing; wait for release
+                    // When receding, we want edge to decrease more slowly
+                    // than the glow.
+                    float factor = mGlowScaleYFinish != 0 ? 1
+                            / (mGlowScaleYFinish * mGlowScaleYFinish)
+                            : Float.MAX_VALUE;
+                    mEdgeScaleY = mEdgeScaleYStart +
+                        (mEdgeScaleYFinish - mEdgeScaleYStart) *
+                            interp * factor;
                     break;
                 case STATE_RECEDE:
                     mState = STATE_IDLE;