Animate Handle Menu Open & Caption Handle Vanish

Animate the handle menu’s opening. For full screen, the caption handle should expand until it assumes the shape of the top handle menu pill (app info pill). The spec for freeform is not yet specified. As the handle menu opens, the caption handle vanishes.

Test: Manually tested in freeform, splitscreen, and fullscreen modes
Bug: 301494758
Change-Id: I8cc7305813c083a2b2ad6c19a523173162bc021e

8 files changed, 321 insertions, 9 deletions

diff --git a/libs/WindowManager/Shell/res/layout/desktop_mode_window_decor_handle_menu.xml b/libs/WindowManager/Shell/res/layout/desktop_mode_window_decor_handle_menu.xml
index ee9f070f6765..87e0b2867090 100644
--- a/libs/WindowManager/Shell/res/layout/desktop_mode_window_decor_handle_menu.xml
+++ b/libs/WindowManager/Shell/res/layout/desktop_mode_window_decor_handle_menu.xml
@@ -22,6 +22,7 @@
     android:orientation="vertical">
 
     <LinearLayout
+        android:id="@+id/app_info_pill"
         android:layout_width="match_parent"
         android:layout_height="@dimen/desktop_mode_handle_menu_app_info_pill_height"
         android:layout_marginTop="@dimen/desktop_mode_handle_menu_margin_top"
@@ -66,6 +67,7 @@
     </LinearLayout>
 
     <LinearLayout
+        android:id="@+id/windowing_pill"
         android:layout_width="match_parent"
         android:layout_height="@dimen/desktop_mode_handle_menu_windowing_pill_height"
         android:layout_marginTop="@dimen/desktop_mode_handle_menu_pill_spacing_margin"
@@ -116,6 +118,7 @@
     </LinearLayout>
 
     <LinearLayout
+        android:id="@+id/more_actions_pill"
         android:layout_width="match_parent"
         android:layout_height="@dimen/desktop_mode_handle_menu_more_actions_pill_height"
         android:layout_marginTop="@dimen/desktop_mode_handle_menu_pill_spacing_margin"
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java
index bb262d3df07f..3aed9ebc6c5e 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecoration.java
@@ -455,7 +455,7 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
     }
 
     /**
-     * Create and display handle menu window
+     * Create and display handle menu window.
      */
     void createHandleMenu() {
         mHandleMenu = new HandleMenu.Builder(this)
@@ -466,15 +466,18 @@ public class DesktopModeWindowDecoration extends WindowDecoration<WindowDecorLin
                 .setLayoutId(mRelayoutParams.mLayoutResId)
                 .setCaptionPosition(mRelayoutParams.mCaptionX, mRelayoutParams.mCaptionY)
                 .setWindowingButtonsVisible(DesktopModeStatus.isEnabled())
+                .setCaptionHeight(mResult.mCaptionHeight)
                 .build();
+        mWindowDecorViewHolder.onHandleMenuOpened();
         mHandleMenu.show();
     }
 
     /**
-     * Close the handle menu window
+     * Close the handle menu window.
      */
     void closeHandleMenu() {
         if (!isHandleMenuActive()) return;
+        mWindowDecorViewHolder.onHandleMenuClosed();
         mHandleMenu.close();
         mHandleMenu = null;
     }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenu.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenu.java
index 15f8f1cfadf2..6391518b5911 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenu.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenu.java
@@ -71,10 +71,13 @@ class HandleMenu {
     private int mMenuHeight;
     private int mMenuWidth;
 
+    private final int mCaptionHeight;
+
 
     HandleMenu(WindowDecoration parentDecor, int layoutResId, int captionX, int captionY,
             View.OnClickListener onClickListener, View.OnTouchListener onTouchListener,
-            Drawable appIcon, CharSequence appName, boolean shouldShowWindowingPill) {
+            Drawable appIcon, CharSequence appName, boolean shouldShowWindowingPill,
+            int captionHeight) {
         mParentDecor = parentDecor;
         mContext = mParentDecor.mDecorWindowContext;
         mTaskInfo = mParentDecor.mTaskInfo;
@@ -86,6 +89,7 @@ class HandleMenu {
         mAppIcon = appIcon;
         mAppName = appName;
         mShouldShowWindowingPill = shouldShowWindowingPill;
+        mCaptionHeight = captionHeight;
         loadHandleMenuDimensions();
         updateHandleMenuPillPositions();
     }
@@ -98,6 +102,7 @@ class HandleMenu {
         ssg.addTransaction(t);
         ssg.markSyncReady();
         setupHandleMenu();
+        animateHandleMenu();
     }
 
     private void createHandleMenuWindow(SurfaceControl.Transaction t, SurfaceSyncGroup ssg) {
@@ -109,6 +114,21 @@ class HandleMenu {
     }
 
     /**
+     * Animates the appearance of the handle menu and its three pills.
+     */
+    private void animateHandleMenu() {
+        final View handleMenuView = mHandleMenuWindow.mWindowViewHost.getView();
+        final HandleMenuAnimator handleMenuAnimator = new HandleMenuAnimator(handleMenuView,
+                mMenuWidth, mCaptionHeight);
+        if (mTaskInfo.getWindowingMode() == WINDOWING_MODE_FULLSCREEN
+                || mTaskInfo.getWindowingMode() == WINDOWING_MODE_MULTI_WINDOW) {
+            handleMenuAnimator.animateCaptionHandleExpandToOpen();
+        } else {
+            handleMenuAnimator.animateOpen();
+        }
+    }
+
+    /**
      * Set up all three pills of the handle menu: app info pill, windowing pill, & more actions
      * pill.
      */
@@ -322,6 +342,7 @@ class HandleMenu {
         private int mCaptionX;
         private int mCaptionY;
         private boolean mShowWindowingPill;
+        private int mCaptionHeight;
 
 
         Builder(@NonNull WindowDecoration parent) {
@@ -364,9 +385,14 @@ class HandleMenu {
             return this;
         }
 
+        Builder setCaptionHeight(int captionHeight) {
+            mCaptionHeight = captionHeight;
+            return this;
+        }
+
         HandleMenu build() {
             return new HandleMenu(mParent, mLayoutId, mCaptionX, mCaptionY, mOnClickListener,
-                    mOnTouchListener, mAppIcon, mName, mShowWindowingPill);
+                    mOnTouchListener, mAppIcon, mName, mShowWindowingPill, mCaptionHeight);
         }
     }
 }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenuAnimator.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenuAnimator.kt
new file mode 100644
index 000000000000..531de1f79ea8
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/HandleMenuAnimator.kt
@@ -0,0 +1,245 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor
+
+import android.animation.Animator
+import android.animation.AnimatorSet
+import android.animation.ObjectAnimator
+import android.view.View
+import android.view.View.ALPHA
+import android.view.View.SCALE_X
+import android.view.View.SCALE_Y
+import android.view.View.TRANSLATION_Y
+import android.view.View.TRANSLATION_Z
+import android.view.ViewGroup
+import androidx.core.view.children
+import com.android.wm.shell.R
+import com.android.wm.shell.animation.Interpolators
+
+/** Animates the Handle Menu opening. */
+class HandleMenuAnimator(
+    private val handleMenu: View,
+    private val menuWidth: Int,
+    private val captionHeight: Float
+) {
+    companion object {
+        private const val MENU_Y_TRANSLATION_DURATION: Long = 150
+        private const val HEADER_NONFREEFORM_SCALE_DURATION: Long = 150
+        private const val HEADER_FREEFORM_SCALE_DURATION: Long = 217
+        private const val HEADER_ELEVATION_DURATION: Long = 83
+        private const val HEADER_CONTENT_ALPHA_DURATION: Long = 100
+        private const val BODY_SCALE_DURATION: Long = 180
+        private const val BODY_ALPHA_DURATION: Long = 150
+        private const val BODY_ELEVATION_DURATION: Long = 83
+        private const val BODY_CONTENT_ALPHA_DURATION: Long = 167
+
+        private const val ELEVATION_DELAY: Long = 33
+        private const val HEADER_CONTENT_ALPHA_DELAY: Long = 67
+        private const val BODY_SCALE_DELAY: Long = 50
+        private const val BODY_ALPHA_DELAY: Long = 133
+
+        private const val HALF_INITIAL_SCALE: Float = 0.5f
+        private const val NONFREEFORM_HEADER_INITIAL_SCALE_X: Float = 0.6f
+        private const val NONFREEFORM_HEADER_INITIAL_SCALE_Y: Float = 0.05f
+    }
+
+    private val animators: MutableList<Animator> = mutableListOf()
+
+    private val appInfoPill: ViewGroup = handleMenu.requireViewById(R.id.app_info_pill)
+    private val windowingPill: ViewGroup = handleMenu.requireViewById(R.id.windowing_pill)
+    private val moreActionsPill: ViewGroup = handleMenu.requireViewById(R.id.more_actions_pill)
+
+    /** Animates the opening of the handle menu. */
+    fun animateOpen() {
+        prepareMenuForAnimation()
+        appInfoPillExpand()
+        animateAppInfoPill()
+        animateWindowingPill()
+        animateMoreActionsPill()
+        runAnimations()
+    }
+
+    /**
+     * Animates the opening of the handle menu. The caption handle in full screen and split screen
+     * will expand until it assumes the shape of the app info pill. Then, the other two pills will
+     * appear.
+     */
+    fun animateCaptionHandleExpandToOpen() {
+        prepareMenuForAnimation()
+        captionHandleExpandIntoAppInfoPill()
+        animateAppInfoPill()
+        animateWindowingPill()
+        animateMoreActionsPill()
+        runAnimations()
+    }
+
+    /**
+     * Prepares the handle menu for animation. Presets the opacity of necessary menu components.
+     * Presets pivots of handle menu and body pills for scaling animation.
+     */
+    private fun prepareMenuForAnimation() {
+        // Preset opacity
+        appInfoPill.children.forEach { it.alpha = 0f }
+        windowingPill.alpha = 0f
+        moreActionsPill.alpha = 0f
+
+        // Setup pivots.
+        handleMenu.pivotX = menuWidth / 2f
+        handleMenu.pivotY = 0f
+
+        windowingPill.pivotX = menuWidth / 2f
+        windowingPill.pivotY = appInfoPill.measuredHeight.toFloat()
+
+        moreActionsPill.pivotX = menuWidth / 2f
+        moreActionsPill.pivotY = appInfoPill.measuredHeight.toFloat()
+    }
+
+    private fun animateAppInfoPill() {
+        // Header Elevation Animation
+        animators +=
+            ObjectAnimator.ofFloat(appInfoPill, TRANSLATION_Z, 1f).apply {
+                startDelay = ELEVATION_DELAY
+                duration = HEADER_ELEVATION_DURATION
+            }
+
+        // Content Opacity Animation
+        appInfoPill.children.forEach {
+            animators +=
+                ObjectAnimator.ofFloat(it, ALPHA, 1f).apply {
+                    startDelay = HEADER_CONTENT_ALPHA_DELAY
+                    duration = HEADER_CONTENT_ALPHA_DURATION
+                }
+        }
+    }
+
+    private fun captionHandleExpandIntoAppInfoPill() {
+        // Header scaling animation
+        animators +=
+            ObjectAnimator.ofFloat(appInfoPill, SCALE_X, NONFREEFORM_HEADER_INITIAL_SCALE_X, 1f)
+                .apply { duration = HEADER_NONFREEFORM_SCALE_DURATION }
+
+        animators +=
+            ObjectAnimator.ofFloat(appInfoPill, SCALE_Y, NONFREEFORM_HEADER_INITIAL_SCALE_Y, 1f)
+                .apply { duration = HEADER_NONFREEFORM_SCALE_DURATION }
+
+        // Downward y-translation animation
+        val yStart: Float = -captionHeight / 2
+        animators +=
+            ObjectAnimator.ofFloat(handleMenu, TRANSLATION_Y, yStart, 0f).apply {
+                duration = MENU_Y_TRANSLATION_DURATION
+            }
+    }
+
+    private fun appInfoPillExpand() {
+        // Header scaling animation
+        animators +=
+            ObjectAnimator.ofFloat(appInfoPill, SCALE_X, HALF_INITIAL_SCALE, 1f).apply {
+                duration = HEADER_FREEFORM_SCALE_DURATION
+            }
+
+        animators +=
+            ObjectAnimator.ofFloat(appInfoPill, SCALE_Y, HALF_INITIAL_SCALE, 1f).apply {
+                duration = HEADER_FREEFORM_SCALE_DURATION
+            }
+    }
+
+    private fun animateWindowingPill() {
+        // Windowing X & Y Scaling Animation
+        animators +=
+            ObjectAnimator.ofFloat(windowingPill, SCALE_X, HALF_INITIAL_SCALE, 1f).apply {
+                startDelay = BODY_SCALE_DELAY
+                duration = BODY_SCALE_DURATION
+            }
+
+        animators +=
+            ObjectAnimator.ofFloat(windowingPill, SCALE_Y, HALF_INITIAL_SCALE, 1f).apply {
+                startDelay = BODY_SCALE_DELAY
+                duration = BODY_SCALE_DURATION
+            }
+
+        // Windowing Opacity Animation
+        animators +=
+            ObjectAnimator.ofFloat(windowingPill, ALPHA, 1f).apply {
+                startDelay = BODY_ALPHA_DELAY
+                duration = BODY_ALPHA_DURATION
+            }
+
+        // Windowing Elevation Animation
+        animators +=
+            ObjectAnimator.ofFloat(windowingPill, TRANSLATION_Z, 1f).apply {
+                startDelay = ELEVATION_DELAY
+                duration = BODY_ELEVATION_DURATION
+            }
+
+        // Windowing Content Opacity Animation
+        windowingPill.children.forEach {
+            animators +=
+                ObjectAnimator.ofFloat(it, ALPHA, 1f).apply {
+                    startDelay = BODY_ALPHA_DELAY
+                    duration = BODY_CONTENT_ALPHA_DURATION
+                    interpolator = Interpolators.FAST_OUT_SLOW_IN
+                }
+        }
+    }
+
+    private fun animateMoreActionsPill() {
+        // More Actions X & Y Scaling Animation
+        animators +=
+            ObjectAnimator.ofFloat(moreActionsPill, SCALE_X, HALF_INITIAL_SCALE, 1f).apply {
+                startDelay = BODY_SCALE_DELAY
+                duration = BODY_SCALE_DURATION
+            }
+
+        animators +=
+            ObjectAnimator.ofFloat(moreActionsPill, SCALE_Y, HALF_INITIAL_SCALE, 1f).apply {
+                startDelay = BODY_SCALE_DELAY
+                duration = BODY_SCALE_DURATION
+            }
+
+        // More Actions Opacity Animation
+        animators +=
+            ObjectAnimator.ofFloat(moreActionsPill, ALPHA, 1f).apply {
+                startDelay = BODY_ALPHA_DELAY
+                duration = BODY_ALPHA_DURATION
+            }
+
+        // More Actions Elevation Animation
+        animators +=
+            ObjectAnimator.ofFloat(moreActionsPill, TRANSLATION_Z, 1f).apply {
+                startDelay = ELEVATION_DELAY
+                duration = BODY_ELEVATION_DURATION
+            }
+
+        // More Actions Content Opacity Animation
+        moreActionsPill.children.forEach {
+            animators +=
+                ObjectAnimator.ofFloat(it, ALPHA, 1f).apply {
+                    startDelay = BODY_ALPHA_DELAY
+                    duration = BODY_CONTENT_ALPHA_DURATION
+                    interpolator = Interpolators.FAST_OUT_SLOW_IN
+                }
+        }
+    }
+
+    /** Runs the list of animators concurrently. */
+    private fun runAnimations() {
+        val animatorSet = AnimatorSet()
+        animatorSet.playTogether(animators)
+        animatorSet.start()
+        animators.clear()
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
index 044c0331282c..634b7558c7d8 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
@@ -269,10 +269,10 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
                     .build();
         }
 
-        final int captionHeight = loadDimensionPixelSize(resources, params.mCaptionHeightId);
+        outResult.mCaptionHeight = loadDimensionPixelSize(resources, params.mCaptionHeightId);
         final int captionWidth = taskBounds.width();
 
-        startT.setWindowCrop(mCaptionContainerSurface, captionWidth, captionHeight)
+        startT.setWindowCrop(mCaptionContainerSurface, captionWidth, outResult.mCaptionHeight)
                 .setLayer(mCaptionContainerSurface, CAPTION_LAYER_Z_ORDER)
                 .show(mCaptionContainerSurface);
 
@@ -283,7 +283,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
             mCaptionInsetsRect.set(taskBounds);
             if (mIsCaptionVisible) {
                 mCaptionInsetsRect.bottom =
-                        mCaptionInsetsRect.top + captionHeight + params.mCaptionY;
+                        mCaptionInsetsRect.top + outResult.mCaptionHeight + params.mCaptionY;
                 wct.addInsetsSource(mTaskInfo.token,
                         mOwner, 0 /* index */, WindowInsets.Type.captionBar(), mCaptionInsetsRect);
                 wct.addInsetsSource(mTaskInfo.token,
@@ -348,7 +348,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
         // Caption view
         mCaptionWindowManager.setConfiguration(taskConfig);
         final WindowManager.LayoutParams lp =
-                new WindowManager.LayoutParams(captionWidth, captionHeight,
+                new WindowManager.LayoutParams(captionWidth, outResult.mCaptionHeight,
                         WindowManager.LayoutParams.TYPE_APPLICATION,
                         WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE, PixelFormat.TRANSPARENT);
         lp.setTitle("Caption of Task=" + mTaskInfo.taskId);
@@ -569,6 +569,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
     }
 
     static class RelayoutResult<T extends View & TaskFocusStateConsumer> {
+        int mCaptionHeight;
         int mWidth;
         int mHeight;
         T mRootView;
@@ -576,6 +577,7 @@ public abstract class WindowDecoration<T extends View & TaskFocusStateConsumer>
         void reset() {
             mWidth = 0;
             mHeight = 0;
+            mCaptionHeight = 0;
             mRootView = null;
         }
     }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeAppControlsWindowDecorationViewHolder.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeAppControlsWindowDecorationViewHolder.kt
index 6b59ccec5148..400dec4df506 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeAppControlsWindowDecorationViewHolder.kt
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeAppControlsWindowDecorationViewHolder.kt
@@ -48,7 +48,6 @@ internal class DesktopModeAppControlsWindowDecorationViewHolder(
     }
 
     override fun bindData(taskInfo: RunningTaskInfo) {
-
         val captionDrawable = captionView.background as GradientDrawable
         taskInfo.taskDescription?.statusBarColor?.let {
             captionDrawable.setColor(it)
@@ -63,6 +62,10 @@ internal class DesktopModeAppControlsWindowDecorationViewHolder(
         appNameTextView.setTextColor(getCaptionAppNameTextColor(taskInfo))
     }
 
+    override fun onHandleMenuOpened() {}
+
+    override fun onHandleMenuClosed() {}
+
     private fun getCaptionAppNameTextColor(taskInfo: RunningTaskInfo): Int {
         return if (shouldUseLightCaptionColors(taskInfo)) {
             context.getColor(R.color.desktop_mode_caption_app_name_light)
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeFocusedWindowDecorationViewHolder.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeFocusedWindowDecorationViewHolder.kt
index 9374ac95e83d..9dc86db4f59b 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeFocusedWindowDecorationViewHolder.kt
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeFocusedWindowDecorationViewHolder.kt
@@ -1,11 +1,13 @@
 package com.android.wm.shell.windowdecor.viewholder
 
+import android.animation.ObjectAnimator
 import android.app.ActivityManager.RunningTaskInfo
 import android.content.res.ColorStateList
 import android.graphics.drawable.GradientDrawable
 import android.view.View
 import android.widget.ImageButton
 import com.android.wm.shell.R
+import com.android.wm.shell.animation.Interpolators
 
 /**
  * A desktop mode window decoration used when the window is in full "focus" (i.e. fullscreen). It
@@ -17,6 +19,10 @@ internal class DesktopModeFocusedWindowDecorationViewHolder(
         onCaptionButtonClickListener: View.OnClickListener
 ) : DesktopModeWindowDecorationViewHolder(rootView) {
 
+    companion object {
+        private const val CAPTION_HANDLE_ANIMATION_DURATION: Long = 100
+    }
+
     private val captionView: View = rootView.requireViewById(R.id.desktop_mode_caption)
     private val captionHandle: ImageButton = rootView.requireViewById(R.id.caption_handle)
 
@@ -35,6 +41,14 @@ internal class DesktopModeFocusedWindowDecorationViewHolder(
         captionHandle.imageTintList = ColorStateList.valueOf(getCaptionHandleBarColor(taskInfo))
     }
 
+    override fun onHandleMenuOpened() {
+        animateCaptionHandleAlpha(startValue = 0f, endValue = 1f)
+    }
+
+    override fun onHandleMenuClosed() {
+        animateCaptionHandleAlpha(startValue = 1f, endValue = 0f)
+    }
+
     private fun getCaptionHandleBarColor(taskInfo: RunningTaskInfo): Int {
         return if (shouldUseLightCaptionColors(taskInfo)) {
             context.getColor(R.color.desktop_mode_caption_handle_bar_light)
@@ -42,4 +56,14 @@ internal class DesktopModeFocusedWindowDecorationViewHolder(
             context.getColor(R.color.desktop_mode_caption_handle_bar_dark)
         }
     }
+
+    /** Animate appearance/disappearance of caption handle as the handle menu is animated. */
+    private fun animateCaptionHandleAlpha(startValue: Float, endValue: Float) {
+        val animator =
+            ObjectAnimator.ofFloat(captionHandle, View.ALPHA, startValue, endValue).apply {
+                duration = CAPTION_HANDLE_ANIMATION_DURATION
+                interpolator = Interpolators.FAST_OUT_SLOW_IN
+            }
+        animator.start()
+    }
 }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeWindowDecorationViewHolder.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeWindowDecorationViewHolder.kt
index 49e8d15dcc02..8b405f02ef29 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeWindowDecorationViewHolder.kt
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/viewholder/DesktopModeWindowDecorationViewHolder.kt
@@ -35,4 +35,10 @@ internal abstract class DesktopModeWindowDecorationViewHolder(rootView: View) {
           }
         } ?: false
   }
+
+    /** Callback when the handle menu is opened. */
+    abstract fun onHandleMenuOpened()
+
+    /** Callback when the handle menu is closed. */
+    abstract fun onHandleMenuClosed()
 }