Apply alpha to status bar during unfold

Status bar icons are displayed only in the last 25% of the unfold progress. Otherwise, during unfold to app scenario, they were going outside the app window.

+ Minor kotlin fixes.

Test: Unfold while app opened
Bug: 210997078
Change-Id: I26ab9cb28ce4d894ad33b6b26e11ae59e28234bd

packages/SystemUI/shared/src/com/android/systemui/shared/animation/UnfoldMoveFromCenterAnimator.kt

@@ -42,7 +42,9 @@ class UnfoldMoveFromCenterAnimator @JvmOverloads constructor(
      * are different than actual bounds (e.g. view container may
      * have larger width than width of the items in the container)
      */
-    private val viewCenterProvider: ViewCenterProvider = object : ViewCenterProvider {}
+    private val viewCenterProvider: ViewCenterProvider = object : ViewCenterProvider {},
+    /** Allows to set the alpha based on the progress. */
+    private val alphaProvider: AlphaProvider? = null
 ) : UnfoldTransitionProgressProvider.TransitionProgressListener {
 
     private val screenSize = Point()
@@ -99,17 +101,27 @@ class UnfoldMoveFromCenterAnimator @JvmOverloads constructor(
 
     override fun onTransitionProgress(progress: Float) {
         animatedViews.forEach {
-            it.view.get()?.let { view ->
-                translationApplier.apply(
-                    view = view,
-                    x = it.startTranslationX * (1 - progress),
-                    y = it.startTranslationY * (1 - progress)
-                )
-            }
+            it.applyTransition(progress)
+            it.applyAlpha(progress)
         }
         lastAnimationProgress = progress
     }
 
+    private fun AnimatedView.applyTransition(progress: Float) {
+        view.get()?.let { view ->
+            translationApplier.apply(
+                view = view,
+                x = startTranslationX * (1 - progress),
+                y = startTranslationY * (1 - progress)
+            )
+        }
+    }
+
+    private fun AnimatedView.applyAlpha(progress: Float) {
+        if (alphaProvider == null) return
+        view.get()?.alpha = alphaProvider.getAlpha(progress)
+    }
+
     private fun createAnimatedView(view: View): AnimatedView =
         AnimatedView(view = WeakReference(view)).updateAnimatedView(view)
 
@@ -146,6 +158,13 @@ class UnfoldMoveFromCenterAnimator @JvmOverloads constructor(
         }
     }
 
+    /** Allows to set a custom alpha based on the progress. */
+    interface AlphaProvider {
+
+        /** Returns the alpha views should have at a given progress. */
+        fun getAlpha(progress: Float): Float
+    }
+
     /**
      * Interface that allows to use custom logic to get the center of the view
      */

packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarViewController.kt

@@ -49,29 +49,29 @@ class PhoneStatusBarViewController private constructor(
     }
 
     override fun onViewAttached() {
-        moveFromCenterAnimationController?.let { animationController ->
-            val statusBarLeftSide: View = mView.findViewById(R.id.status_bar_left_side)
-            val systemIconArea: ViewGroup = mView.findViewById(R.id.system_icon_area)
+        if (moveFromCenterAnimationController == null) return
 
-            val viewsToAnimate = arrayOf(
-                statusBarLeftSide,
-                systemIconArea
-            )
+        val statusBarLeftSide: View = mView.findViewById(R.id.status_bar_left_side)
+        val systemIconArea: ViewGroup = mView.findViewById(R.id.system_icon_area)
 
-            mView.viewTreeObserver.addOnPreDrawListener(object :
-                ViewTreeObserver.OnPreDrawListener {
-                override fun onPreDraw(): Boolean {
-                    animationController.onViewsReady(viewsToAnimate)
-                    mView.viewTreeObserver.removeOnPreDrawListener(this)
-                    return true
-                }
-            })
+        val viewsToAnimate = arrayOf(
+            statusBarLeftSide,
+            systemIconArea
+        )
 
-            mView.addOnLayoutChangeListener { _, left, _, right, _, oldLeft, _, oldRight, _ ->
-                val widthChanged = right - left != oldRight - oldLeft
-                if (widthChanged) {
-                    moveFromCenterAnimationController.onStatusBarWidthChanged()
-                }
+        mView.viewTreeObserver.addOnPreDrawListener(object :
+            ViewTreeObserver.OnPreDrawListener {
+            override fun onPreDraw(): Boolean {
+                moveFromCenterAnimationController.onViewsReady(viewsToAnimate)
+                mView.viewTreeObserver.removeOnPreDrawListener(this)
+                return true
+            }
+        })
+
+        mView.addOnLayoutChangeListener { _, left, _, right, _, oldLeft, _, oldRight, _ ->
+            val widthChanged = right - left != oldRight - oldLeft
+            if (widthChanged) {
+                moveFromCenterAnimationController.onStatusBarWidthChanged()
             }
         }
 
@@ -162,9 +162,7 @@ class PhoneStatusBarViewController private constructor(
             PhoneStatusBarViewController(
                 view,
                 progressProvider.getOrNull(),
-                unfoldComponent.map {
-                    it.getStatusBarMoveFromCenterAnimationController()
-                }.getOrNull(),
+                unfoldComponent.getOrNull()?.getStatusBarMoveFromCenterAnimationController(),
                 touchEventHandler,
                 configurationController
             )

packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarMoveFromCenterAnimationController.kt

@@ -18,11 +18,13 @@ package com.android.systemui.statusbar.phone
 import android.view.View
 import android.view.WindowManager
 import com.android.systemui.shared.animation.UnfoldMoveFromCenterAnimator
+import com.android.systemui.shared.animation.UnfoldMoveFromCenterAnimator.AlphaProvider
 import com.android.systemui.statusbar.phone.PhoneStatusBarViewController.StatusBarViewsCenterProvider
 import com.android.systemui.unfold.SysUIUnfoldScope
 import com.android.systemui.unfold.UnfoldTransitionProgressProvider.TransitionProgressListener
 import com.android.systemui.unfold.util.ScopedUnfoldTransitionProgressProvider
 import javax.inject.Inject
+import kotlin.math.max
 
 @SysUIUnfoldScope
 class StatusBarMoveFromCenterAnimationController @Inject constructor(
@@ -31,8 +33,11 @@ class StatusBarMoveFromCenterAnimationController @Inject constructor(
 ) {
 
     private val transitionListener = TransitionListener()
-    private val moveFromCenterAnimator = UnfoldMoveFromCenterAnimator(windowManager,
-        viewCenterProvider = StatusBarViewsCenterProvider())
+    private val moveFromCenterAnimator = UnfoldMoveFromCenterAnimator(
+        windowManager,
+        viewCenterProvider = StatusBarViewsCenterProvider(),
+        alphaProvider = StatusBarIconsAlphaProvider()
+    )
 
     fun onViewsReady(viewsToAnimate: Array<View>) {
         moveFromCenterAnimator.updateDisplayProperties()
@@ -65,4 +70,15 @@ class StatusBarMoveFromCenterAnimationController @Inject constructor(
             moveFromCenterAnimator.onTransitionProgress(1f)
         }
     }
+
+    private class StatusBarIconsAlphaProvider : AlphaProvider {
+        override fun getAlpha(progress: Float): Float {
+            return max(
+                0f,
+                (progress - ICONS_START_APPEARING_PROGRESS) / (1 - ICONS_START_APPEARING_PROGRESS)
+            )
+        }
+    }
 }
+
+private const val ICONS_START_APPEARING_PROGRESS = 0.75F