From 9de91d3cba368cdb94ffc6475bd7ae5574597d37 Mon Sep 17 00:00:00 2001
From: Jordan Demeulenaere <jdemeulenaere@google.com>
Date: Fri, 9 Apr 2021 16:56:24 +0200
Subject: [PATCH] Scale the expanding view content towards the center.

This CL scales the content of the view that is expanding during an
animated activity launch. The content also now moves towards the center
of the final window position.

Bug: 184726377
Test: Manual
Change-Id: Ibca1c4f5f56d99878d6c79dab033a2e7d7a4928b
---
 .../animation/ActivityLaunchAnimator.kt       | 20 +++++++++++++++++++
 .../GhostedViewLaunchAnimatorController.kt    | 20 ++++++++++++++++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/packages/SystemUI/animation/src/com/android/systemui/animation/ActivityLaunchAnimator.kt b/packages/SystemUI/animation/src/com/android/systemui/animation/ActivityLaunchAnimator.kt
index fc03a9ee9c5f5..da78a7c24d0fd 100644
--- a/packages/SystemUI/animation/src/com/android/systemui/animation/ActivityLaunchAnimator.kt
+++ b/packages/SystemUI/animation/src/com/android/systemui/animation/ActivityLaunchAnimator.kt
@@ -223,8 +223,13 @@ class ActivityLaunchAnimator(context: Context) {
         var backgroundAlpha: Float = 1f
     ) {
         private val startTop = top
+        private val startBottom = bottom
         private val startLeft = left
         private val startRight = right
+        private val startWidth = width
+        private val startHeight = height
+        val startCenterX = centerX
+        val startCenterY = centerY
 
         val width: Int
             get() = right - left
@@ -235,11 +240,26 @@ class ActivityLaunchAnimator(context: Context) {
         open val topChange: Int
             get() = top - startTop
 
+        open val bottomChange: Int
+            get() = bottom - startBottom
+
         val leftChange: Int
             get() = left - startLeft
 
         val rightChange: Int
             get() = right - startRight
+
+        val widthRatio: Float
+            get() = width.toFloat() / startWidth
+
+        val heightRatio: Float
+            get() = height.toFloat() / startHeight
+
+        val centerX: Float
+            get() = left + width / 2f
+
+        val centerY: Float
+            get() = top + height / 2f
     }
 
     @VisibleForTesting
diff --git a/packages/SystemUI/animation/src/com/android/systemui/animation/GhostedViewLaunchAnimatorController.kt b/packages/SystemUI/animation/src/com/android/systemui/animation/GhostedViewLaunchAnimatorController.kt
index bbbe3dddcf8d4..01ec447e5685a 100644
--- a/packages/SystemUI/animation/src/com/android/systemui/animation/GhostedViewLaunchAnimatorController.kt
+++ b/packages/SystemUI/animation/src/com/android/systemui/animation/GhostedViewLaunchAnimatorController.kt
@@ -2,6 +2,7 @@ package com.android.systemui.animation
 
 import android.graphics.Canvas
 import android.graphics.ColorFilter
+import android.graphics.Matrix
 import android.graphics.PixelFormat
 import android.graphics.PorterDuff
 import android.graphics.PorterDuffXfermode
@@ -13,6 +14,7 @@ import android.view.GhostView
 import android.view.View
 import android.view.ViewGroup
 import android.widget.FrameLayout
+import kotlin.math.min
 
 /**
  * A base implementation of [ActivityLaunchAnimator.Controller] which creates a [ghost][GhostView]
@@ -34,7 +36,9 @@ open class GhostedViewLaunchAnimatorController(
     private val rootViewOverlay = rootView.overlay
 
     /** The ghost view that is drawn and animated instead of the ghosted view. */
-    private var ghostView: View? = null
+    private var ghostView: GhostView? = null
+    private val initialGhostViewMatrixValues = FloatArray(9) { 0f }
+    private val ghostViewMatrix = Matrix()
 
     /**
      * The expanding background view that will be added to [rootView] (below [ghostView]) and
@@ -125,6 +129,9 @@ open class GhostedViewLaunchAnimatorController(
         ghostView = GhostView.addGhost(ghostedView, rootView).apply {
             setLayerType(View.LAYER_TYPE_HARDWARE, null)
         }
+
+        val matrix = ghostView?.animationMatrix ?: Matrix.IDENTITY_MATRIX
+        matrix.getValues(initialGhostViewMatrixValues)
     }
 
     override fun onLaunchAnimationProgress(
@@ -133,10 +140,17 @@ open class GhostedViewLaunchAnimatorController(
         linearProgress: Float
     ) {
         val ghostView = this.ghostView!!
-        ghostView.translationX = (state.leftChange + state.rightChange) / 2.toFloat()
-        ghostView.translationY = state.topChange.toFloat()
         ghostView.alpha = state.contentAlpha
 
+        val scale = min(state.widthRatio, state.heightRatio)
+        ghostViewMatrix.setValues(initialGhostViewMatrixValues)
+        ghostViewMatrix.postScale(scale, scale, state.startCenterX, state.startCenterY)
+        ghostViewMatrix.postTranslate(
+                (state.leftChange + state.rightChange) / 2f,
+                (state.topChange + state.bottomChange) / 2f
+        )
+        ghostView.animationMatrix = ghostViewMatrix
+
         val backgroundView = this.backgroundView!!
         backgroundView.top = state.top
         backgroundView.bottom = state.bottom