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

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

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