From bcc64e2cf47fe53bac1cea1548fd2049e4e38be6 Mon Sep 17 00:00:00 2001
From: ztenghui <ztenghui@google.com>
Date: Wed, 4 Oct 2017 15:45:44 -0700
Subject: [PATCH] Update ripple according to UX feedback.

1. Consistent enter and exit duration and speed. Both bounded and
unbouned. It used to be that exit is much faster than enter.

2. Instead of starting from 0 size radius, we start from some size
according to the current drawable's bound.

b/63635160
Test: demo app, settings app and calculator app

Change-Id: I1135fefc9d9103f170ab889269b38a9900835450
---
 .../graphics/drawable/RippleDrawable.java     |  1 -
 .../graphics/drawable/RippleForeground.java   | 23 +++++++++++--------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/graphics/java/android/graphics/drawable/RippleDrawable.java b/graphics/java/android/graphics/drawable/RippleDrawable.java
index b090681a6f91b..1727eca544a9f 100644
--- a/graphics/java/android/graphics/drawable/RippleDrawable.java
+++ b/graphics/java/android/graphics/drawable/RippleDrawable.java
@@ -269,7 +269,6 @@ public class RippleDrawable extends LayerDrawable {
         setRippleActive(focused || (enabled && pressed));
 
         setBackgroundActive(hovered, hovered);
-
         return changed;
     }
 
diff --git a/graphics/java/android/graphics/drawable/RippleForeground.java b/graphics/java/android/graphics/drawable/RippleForeground.java
index 0de3f114dc2ea..ed417b97bbeb7 100644
--- a/graphics/java/android/graphics/drawable/RippleForeground.java
+++ b/graphics/java/android/graphics/drawable/RippleForeground.java
@@ -41,7 +41,6 @@ class RippleForeground extends RippleComponent {
 
     // Pixel-based accelerations and velocities.
     private static final float WAVE_TOUCH_DOWN_ACCELERATION = 1024;
-    private static final float WAVE_TOUCH_UP_ACCELERATION = 3400;
     private static final float WAVE_OPACITY_DECAY_VELOCITY = 3;
 
     // Bounded ripple animation properties.
@@ -83,6 +82,11 @@ class RippleForeground extends RippleComponent {
     /** Whether this ripple has finished its exit animation. */
     private boolean mHasFinishedExit;
 
+    /**
+     * If we have a bound, don't start from 0. Start from 60% of the max out of width and height.
+     */
+    private float mStartRadius = 0;
+
     public RippleForeground(RippleDrawable owner, Rect bounds, float startingX, float startingY,
             boolean isBounded, boolean forceSoftware) {
         super(owner, bounds, forceSoftware);
@@ -96,6 +100,8 @@ class RippleForeground extends RippleComponent {
         } else {
             mBoundedRadius = 0;
         }
+        // Take 60% of the maximum of the width and height, then divided half to get the radius.
+        mStartRadius = Math.max(bounds.width(), bounds.height()) * 0.3f;
     }
 
     @Override
@@ -158,8 +164,7 @@ class RippleForeground extends RippleComponent {
 
     @Override
     protected Animator createSoftwareEnter(boolean fast) {
-        final int duration = (int)
-                (1000 * Math.sqrt(mTargetRadius / WAVE_TOUCH_DOWN_ACCELERATION * mDensityScale) + 0.5);
+        final int duration = getRadiusDuration();
 
         final ObjectAnimator tweenRadius = ObjectAnimator.ofFloat(this, TWEEN_RADIUS, 1);
         tweenRadius.setAutoCancel(true);
@@ -192,14 +197,14 @@ class RippleForeground extends RippleComponent {
         return MathUtils.lerp(mClampedStartingY - mBounds.exactCenterY(), mTargetY, mTweenY);
     }
 
-    private int getRadiusExitDuration() {
+    private int getRadiusDuration() {
         final float remainingRadius = mTargetRadius - getCurrentRadius();
-        return (int) (1000 * Math.sqrt(remainingRadius / (WAVE_TOUCH_UP_ACCELERATION
-                + WAVE_TOUCH_DOWN_ACCELERATION) * mDensityScale) + 0.5);
+        return (int) (1000 * Math.sqrt(remainingRadius / WAVE_TOUCH_DOWN_ACCELERATION *
+                mDensityScale) + 0.5);
     }
 
     private float getCurrentRadius() {
-        return MathUtils.lerp(0, mTargetRadius, mTweenRadius);
+        return MathUtils.lerp(mStartRadius, mTargetRadius, mTweenRadius);
     }
 
     private int getOpacityExitDuration() {
@@ -212,7 +217,7 @@ class RippleForeground extends RippleComponent {
         final int originDuration;
         final int opacityDuration;
 
-        radiusDuration = getRadiusExitDuration();
+        radiusDuration = getRadiusDuration();
         originDuration = radiusDuration;
         opacityDuration = getOpacityExitDuration();
 
@@ -244,7 +249,7 @@ class RippleForeground extends RippleComponent {
         final int originDuration;
         final int opacityDuration;
 
-        radiusDuration = getRadiusExitDuration();
+        radiusDuration = getRadiusDuration();
         originDuration = radiusDuration;
         opacityDuration = getOpacityExitDuration();