Add full-width caption on Shell.

This CL adds a default full-width caption implementation on Shell to act
as a stable caption implementation in freeform windowing environment,
since the desktop mode caption is not yet finalized.
Currently, this caption is used unless the desktop mode flag is turned
on.

Bug: 260276028
Test: atest WMShellUnitTests
Change-Id: I354330cfb959b453e382fed44d87ca7f0308a4e2

9 files changed, 712 insertions, 43 deletions

diff --git a/libs/WindowManager/Shell/res/drawable/caption_decor_title.xml b/libs/WindowManager/Shell/res/drawable/caption_decor_title.xml
new file mode 100644
index 000000000000..6114ad6e277a
--- /dev/null
+++ b/libs/WindowManager/Shell/res/drawable/caption_decor_title.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ 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.
+  -->
+<shape android:shape="rectangle"
+       android:tintMode="multiply"
+       android:tint="@color/decor_title_color"
+       xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="@android:color/white" />
+</shape>
diff --git a/libs/WindowManager/Shell/res/drawable/decor_minimize_button_dark.xml b/libs/WindowManager/Shell/res/drawable/decor_minimize_button_dark.xml
index b7ff96e64eec..91edbf1a7bd4 100644
--- a/libs/WindowManager/Shell/res/drawable/decor_minimize_button_dark.xml
+++ b/libs/WindowManager/Shell/res/drawable/decor_minimize_button_dark.xml
@@ -14,10 +14,10 @@
   ~ limitations under the License.
   -->
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
-        android:width="24dp"
-        android:height="24dp"
-        android:viewportWidth="24"
-        android:viewportHeight="24"
+        android:width="32.0dp"
+        android:height="32.0dp"
+        android:viewportWidth="32.0"
+        android:viewportHeight="32.0"
         android:tint="@color/decor_button_dark_color">
     <path
         android:fillColor="@android:color/white" android:pathData="M6,21V19H18V21Z"/>
diff --git a/libs/WindowManager/Shell/res/layout/caption_window_decor.xml b/libs/WindowManager/Shell/res/layout/caption_window_decor.xml
new file mode 100644
index 000000000000..f3d219872001
--- /dev/null
+++ b/libs/WindowManager/Shell/res/layout/caption_window_decor.xml
@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ 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.
+  -->
+<com.android.wm.shell.windowdecor.WindowDecorLinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/caption"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:gravity="end"
+    android:background="@drawable/caption_decor_title">
+    <Button
+        style="@style/CaptionButtonStyle"
+        android:id="@+id/back_button"
+        android:layout_gravity="center_vertical|end"
+        android:contentDescription="@string/back_button_text"
+        android:background="@drawable/decor_back_button_dark"
+        android:duplicateParentState="true"/>
+    <Space
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_weight="1"
+        android:elevation="2dp"/>
+    <Button
+        style="@style/CaptionButtonStyle"
+        android:id="@+id/minimize_window"
+        android:layout_gravity="center_vertical|end"
+        android:contentDescription="@string/minimize_button_text"
+        android:background="@drawable/decor_minimize_button_dark"
+        android:duplicateParentState="true"/>
+    <Button
+        style="@style/CaptionButtonStyle"
+        android:id="@+id/maximize_window"
+        android:layout_gravity="center_vertical|end"
+        android:contentDescription="@string/maximize_button_text"
+        android:background="@drawable/decor_maximize_button_dark"
+        android:duplicateParentState="true"/>
+    <Button
+        style="@style/CaptionButtonStyle"
+        android:id="@+id/close_window"
+        android:contentDescription="@string/close_button_text"
+        android:background="@drawable/decor_close_button_dark"
+        android:duplicateParentState="true"/>
+</com.android.wm.shell.windowdecor.WindowDecorLinearLayout>
\ No newline at end of file
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
index d3b9fa5e628d..512a4ef386bb 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
@@ -49,6 +49,7 @@ import com.android.wm.shell.common.TransactionPool;
 import com.android.wm.shell.common.annotations.ShellBackgroundThread;
 import com.android.wm.shell.common.annotations.ShellMainThread;
 import com.android.wm.shell.desktopmode.DesktopModeController;
+import com.android.wm.shell.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.desktopmode.DesktopModeTaskRepository;
 import com.android.wm.shell.desktopmode.DesktopTasksController;
 import com.android.wm.shell.draganddrop.DragAndDropController;
@@ -93,6 +94,7 @@ import com.android.wm.shell.unfold.animation.SplitTaskUnfoldAnimator;
 import com.android.wm.shell.unfold.animation.UnfoldTaskAnimator;
 import com.android.wm.shell.unfold.qualifier.UnfoldShellTransition;
 import com.android.wm.shell.unfold.qualifier.UnfoldTransition;
+import com.android.wm.shell.windowdecor.CaptionWindowDecorViewModel;
 import com.android.wm.shell.windowdecor.DesktopModeWindowDecorViewModel;
 import com.android.wm.shell.windowdecor.WindowDecorViewModel;
 
@@ -192,7 +194,8 @@ public abstract class WMShellModule {
             SyncTransactionQueue syncQueue,
             Optional<DesktopModeController> desktopModeController,
             Optional<DesktopTasksController> desktopTasksController) {
-        return new DesktopModeWindowDecorViewModel(
+        if (DesktopModeStatus.isAnyEnabled()) {
+            return new DesktopModeWindowDecorViewModel(
                     context,
                     mainHandler,
                     mainChoreographer,
@@ -201,6 +204,14 @@ public abstract class WMShellModule {
                     syncQueue,
                     desktopModeController,
                     desktopTasksController);
+        }
+        return new CaptionWindowDecorViewModel(
+                    context,
+                    mainHandler,
+                    mainChoreographer,
+                    taskOrganizer,
+                    displayController,
+                    syncQueue);
     }
 
     //
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
new file mode 100644
index 000000000000..1e72c565157a
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
@@ -0,0 +1,266 @@
+/*
+ * 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 static android.app.WindowConfiguration.ACTIVITY_TYPE_STANDARD;
+import static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
+import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
+
+import android.app.ActivityManager.RunningTaskInfo;
+import android.content.Context;
+import android.os.Handler;
+import android.util.SparseArray;
+import android.view.Choreographer;
+import android.view.MotionEvent;
+import android.view.SurfaceControl;
+import android.view.View;
+import android.window.WindowContainerToken;
+import android.window.WindowContainerTransaction;
+
+import com.android.wm.shell.R;
+import com.android.wm.shell.ShellTaskOrganizer;
+import com.android.wm.shell.common.DisplayController;
+import com.android.wm.shell.common.SyncTransactionQueue;
+import com.android.wm.shell.freeform.FreeformTaskTransitionStarter;
+
+/**
+ * View model for the window decoration with a caption and shadows. Works with
+ * {@link CaptionWindowDecoration}.
+ */
+public class CaptionWindowDecorViewModel implements WindowDecorViewModel {
+    private final ShellTaskOrganizer mTaskOrganizer;
+    private final Context mContext;
+    private final Handler mMainHandler;
+    private final Choreographer mMainChoreographer;
+    private final DisplayController mDisplayController;
+    private final SyncTransactionQueue mSyncQueue;
+    private TaskOperations mTaskOperations;
+
+    private final SparseArray<CaptionWindowDecoration> mWindowDecorByTaskId = new SparseArray<>();
+
+    public CaptionWindowDecorViewModel(
+            Context context,
+            Handler mainHandler,
+            Choreographer mainChoreographer,
+            ShellTaskOrganizer taskOrganizer,
+            DisplayController displayController,
+            SyncTransactionQueue syncQueue) {
+        mContext = context;
+        mMainHandler = mainHandler;
+        mMainChoreographer = mainChoreographer;
+        mTaskOrganizer = taskOrganizer;
+        mDisplayController = displayController;
+        mSyncQueue = syncQueue;
+    }
+
+    @Override
+    public void setFreeformTaskTransitionStarter(FreeformTaskTransitionStarter transitionStarter) {
+        mTaskOperations = new TaskOperations(transitionStarter, mContext, mSyncQueue);
+    }
+
+    @Override
+    public boolean onTaskOpening(
+            RunningTaskInfo taskInfo,
+            SurfaceControl taskSurface,
+            SurfaceControl.Transaction startT,
+            SurfaceControl.Transaction finishT) {
+        if (!shouldShowWindowDecor(taskInfo)) return false;
+        createWindowDecoration(taskInfo, taskSurface, startT, finishT);
+        return true;
+    }
+
+    @Override
+    public void onTaskInfoChanged(RunningTaskInfo taskInfo) {
+        final CaptionWindowDecoration decoration = mWindowDecorByTaskId.get(taskInfo.taskId);
+
+        if (decoration == null) return;
+
+        decoration.relayout(taskInfo);
+        setupCaptionColor(taskInfo, decoration);
+    }
+
+    @Override
+    public void onTaskChanging(
+            RunningTaskInfo taskInfo,
+            SurfaceControl taskSurface,
+            SurfaceControl.Transaction startT,
+            SurfaceControl.Transaction finishT) {
+        final CaptionWindowDecoration decoration = mWindowDecorByTaskId.get(taskInfo.taskId);
+
+        if (!shouldShowWindowDecor(taskInfo)) {
+            if (decoration != null) {
+                destroyWindowDecoration(taskInfo);
+            }
+            return;
+        }
+
+        if (decoration == null) {
+            createWindowDecoration(taskInfo, taskSurface, startT, finishT);
+        } else {
+            decoration.relayout(taskInfo, startT, finishT);
+        }
+    }
+
+    @Override
+    public void onTaskClosing(
+            RunningTaskInfo taskInfo,
+            SurfaceControl.Transaction startT,
+            SurfaceControl.Transaction finishT) {
+        final CaptionWindowDecoration decoration = mWindowDecorByTaskId.get(taskInfo.taskId);
+        if (decoration == null) return;
+
+        decoration.relayout(taskInfo, startT, finishT);
+    }
+
+    @Override
+    public void destroyWindowDecoration(RunningTaskInfo taskInfo) {
+        final CaptionWindowDecoration decoration =
+                mWindowDecorByTaskId.removeReturnOld(taskInfo.taskId);
+        if (decoration == null) return;
+
+        decoration.close();
+    }
+
+    private void setupCaptionColor(RunningTaskInfo taskInfo, CaptionWindowDecoration decoration) {
+        int statusBarColor = taskInfo.taskDescription.getStatusBarColor();
+        decoration.setCaptionColor(statusBarColor);
+    }
+
+    private boolean shouldShowWindowDecor(RunningTaskInfo taskInfo) {
+        return taskInfo.getWindowingMode() == WINDOWING_MODE_FREEFORM
+                || (taskInfo.getActivityType() == ACTIVITY_TYPE_STANDARD
+                    && taskInfo.configuration.windowConfiguration.getDisplayWindowingMode()
+                        == WINDOWING_MODE_FREEFORM);
+    }
+
+    private void createWindowDecoration(
+            RunningTaskInfo taskInfo,
+            SurfaceControl taskSurface,
+            SurfaceControl.Transaction startT,
+            SurfaceControl.Transaction finishT) {
+        CaptionWindowDecoration oldDecoration = mWindowDecorByTaskId.get(taskInfo.taskId);
+        if (oldDecoration != null) {
+            // close the old decoration if it exists to avoid two window decorations being added
+            oldDecoration.close();
+        }
+        final CaptionWindowDecoration windowDecoration =
+                new CaptionWindowDecoration(
+                        mContext,
+                        mDisplayController,
+                        mTaskOrganizer,
+                        taskInfo,
+                        taskSurface,
+                        mMainHandler,
+                        mMainChoreographer,
+                        mSyncQueue);
+        mWindowDecorByTaskId.put(taskInfo.taskId, windowDecoration);
+
+        TaskPositioner taskPositioner =
+                new TaskPositioner(mTaskOrganizer, windowDecoration);
+        CaptionTouchEventListener touchEventListener =
+                new CaptionTouchEventListener(taskInfo, taskPositioner);
+        windowDecoration.setCaptionListeners(touchEventListener, touchEventListener);
+        windowDecoration.setDragResizeCallback(taskPositioner);
+        windowDecoration.relayout(taskInfo, startT, finishT);
+        setupCaptionColor(taskInfo, windowDecoration);
+    }
+
+    private class CaptionTouchEventListener implements
+            View.OnClickListener, View.OnTouchListener {
+
+        private final int mTaskId;
+        private final WindowContainerToken mTaskToken;
+        private final DragResizeCallback mDragResizeCallback;
+
+        private int mDragPointerId = -1;
+
+        private CaptionTouchEventListener(
+                RunningTaskInfo taskInfo,
+                DragResizeCallback dragResizeCallback) {
+            mTaskId = taskInfo.taskId;
+            mTaskToken = taskInfo.token;
+            mDragResizeCallback = dragResizeCallback;
+        }
+
+        @Override
+        public void onClick(View v) {
+            final int id = v.getId();
+            if (id == R.id.close_window) {
+                mTaskOperations.closeTask(mTaskToken);
+            } else if (id == R.id.back_button) {
+                mTaskOperations.injectBackKey();
+            } else if (id == R.id.minimize_window) {
+                mTaskOperations.minimizeTask(mTaskToken);
+            } else if (id == R.id.maximize_window) {
+                RunningTaskInfo taskInfo = mTaskOrganizer.getRunningTaskInfo(mTaskId);
+                mTaskOperations.maximizeTask(taskInfo);
+            }
+        }
+
+        @Override
+        public boolean onTouch(View v, MotionEvent e) {
+            if (v.getId() != R.id.caption) {
+                return false;
+            }
+            handleEventForMove(e);
+
+            if (e.getAction() != MotionEvent.ACTION_DOWN) {
+                return false;
+            }
+            RunningTaskInfo taskInfo = mTaskOrganizer.getRunningTaskInfo(mTaskId);
+            if (taskInfo.isFocused) {
+                return false;
+            }
+            WindowContainerTransaction wct = new WindowContainerTransaction();
+            wct.reorder(mTaskToken, true /* onTop */);
+            mSyncQueue.queue(wct);
+            return true;
+        }
+
+        /**
+         * @param e {@link MotionEvent} to process
+         * @return {@code true} if a drag is happening; or {@code false} if it is not
+         */
+        private void handleEventForMove(MotionEvent e) {
+            RunningTaskInfo taskInfo = mTaskOrganizer.getRunningTaskInfo(mTaskId);
+            if (taskInfo.getWindowingMode() == WINDOWING_MODE_FULLSCREEN) {
+                return;
+            }
+            switch (e.getActionMasked()) {
+                case MotionEvent.ACTION_DOWN: {
+                    mDragPointerId = e.getPointerId(0);
+                    mDragResizeCallback.onDragResizeStart(
+                            0 /* ctrlType */, e.getRawX(0), e.getRawY(0));
+                    break;
+                }
+                case MotionEvent.ACTION_MOVE: {
+                    int dragPointerIdx = e.findPointerIndex(mDragPointerId);
+                    mDragResizeCallback.onDragResizeMove(
+                            e.getRawX(dragPointerIdx), e.getRawY(dragPointerIdx));
+                    break;
+                }
+                case MotionEvent.ACTION_UP:
+                case MotionEvent.ACTION_CANCEL: {
+                    int dragPointerIdx = e.findPointerIndex(mDragPointerId);
+                    mDragResizeCallback.onDragResizeEnd(
+                            e.getRawX(dragPointerIdx), e.getRawY(dragPointerIdx));
+                    break;
+                }
+            }
+        }
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
new file mode 100644
index 000000000000..8609c6b0302a
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
@@ -0,0 +1,228 @@
+/*
+ * 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.app.ActivityManager.RunningTaskInfo;
+import android.app.WindowConfiguration;
+import android.content.Context;
+import android.content.res.ColorStateList;
+import android.graphics.Color;
+import android.graphics.drawable.GradientDrawable;
+import android.graphics.drawable.VectorDrawable;
+import android.os.Handler;
+import android.view.Choreographer;
+import android.view.SurfaceControl;
+import android.view.View;
+import android.view.ViewConfiguration;
+import android.window.WindowContainerTransaction;
+
+import com.android.wm.shell.R;
+import com.android.wm.shell.ShellTaskOrganizer;
+import com.android.wm.shell.common.DisplayController;
+import com.android.wm.shell.common.SyncTransactionQueue;
+
+/**
+ * Defines visuals and behaviors of a window decoration of a caption bar and shadows. It works with
+ * {@link CaptionWindowDecorViewModel}. The caption bar contains a back button, minimize button,
+ * maximize button and close button.
+ */
+public class CaptionWindowDecoration extends WindowDecoration<WindowDecorLinearLayout> {
+    private final Handler mHandler;
+    private final Choreographer mChoreographer;
+    private final SyncTransactionQueue mSyncQueue;
+
+    private View.OnClickListener mOnCaptionButtonClickListener;
+    private View.OnTouchListener mOnCaptionTouchListener;
+    private DragResizeCallback mDragResizeCallback;
+
+    private DragResizeInputListener mDragResizeListener;
+
+    private RelayoutParams mRelayoutParams = new RelayoutParams();
+    private final RelayoutResult<WindowDecorLinearLayout> mResult =
+            new RelayoutResult<>();
+
+    private DragDetector mDragDetector;
+
+    CaptionWindowDecoration(
+            Context context,
+            DisplayController displayController,
+            ShellTaskOrganizer taskOrganizer,
+            RunningTaskInfo taskInfo,
+            SurfaceControl taskSurface,
+            Handler handler,
+            Choreographer choreographer,
+            SyncTransactionQueue syncQueue) {
+        super(context, displayController, taskOrganizer, taskInfo, taskSurface);
+
+        mHandler = handler;
+        mChoreographer = choreographer;
+        mSyncQueue = syncQueue;
+        mDragDetector = new DragDetector(ViewConfiguration.get(context).getScaledTouchSlop());
+    }
+
+    void setCaptionListeners(
+            View.OnClickListener onCaptionButtonClickListener,
+            View.OnTouchListener onCaptionTouchListener) {
+        mOnCaptionButtonClickListener = onCaptionButtonClickListener;
+        mOnCaptionTouchListener = onCaptionTouchListener;
+    }
+
+    void setDragResizeCallback(DragResizeCallback dragResizeCallback) {
+        mDragResizeCallback = dragResizeCallback;
+    }
+
+    @Override
+    void relayout(RunningTaskInfo taskInfo) {
+        final SurfaceControl.Transaction t = new SurfaceControl.Transaction();
+        relayout(taskInfo, t, t);
+        mSyncQueue.runInSync(transaction -> {
+            transaction.merge(t);
+            t.close();
+        });
+    }
+
+    void relayout(RunningTaskInfo taskInfo,
+            SurfaceControl.Transaction startT, SurfaceControl.Transaction finishT) {
+        final int shadowRadiusID = taskInfo.isFocused
+                ? R.dimen.freeform_decor_shadow_focused_thickness
+                : R.dimen.freeform_decor_shadow_unfocused_thickness;
+        final boolean isFreeform =
+                taskInfo.getWindowingMode() == WindowConfiguration.WINDOWING_MODE_FREEFORM;
+        final boolean isDragResizeable = isFreeform && taskInfo.isResizeable;
+
+        WindowDecorLinearLayout oldRootView = mResult.mRootView;
+        final SurfaceControl oldDecorationSurface = mDecorationContainerSurface;
+        final WindowContainerTransaction wct = new WindowContainerTransaction();
+
+        int outsetLeftId = R.dimen.freeform_resize_handle;
+        int outsetTopId = R.dimen.freeform_resize_handle;
+        int outsetRightId = R.dimen.freeform_resize_handle;
+        int outsetBottomId = R.dimen.freeform_resize_handle;
+
+        mRelayoutParams.reset();
+        mRelayoutParams.mRunningTaskInfo = taskInfo;
+        mRelayoutParams.mLayoutResId = R.layout.caption_window_decor;
+        mRelayoutParams.mCaptionHeightId = R.dimen.freeform_decor_caption_height;
+        mRelayoutParams.mShadowRadiusId = shadowRadiusID;
+        if (isDragResizeable) {
+            mRelayoutParams.setOutsets(outsetLeftId, outsetTopId, outsetRightId, outsetBottomId);
+        }
+
+        relayout(mRelayoutParams, startT, finishT, wct, oldRootView, mResult);
+        taskInfo = null; // Clear it just in case we use it accidentally
+
+        mTaskOrganizer.applyTransaction(wct);
+
+        if (mResult.mRootView == null) {
+            // This means something blocks the window decor from showing, e.g. the task is hidden.
+            // Nothing is set up in this case including the decoration surface.
+            return;
+        }
+        if (oldRootView != mResult.mRootView) {
+            setupRootView();
+        }
+
+        if (!isDragResizeable) {
+            closeDragResizeListener();
+            return;
+        }
+
+        if (oldDecorationSurface != mDecorationContainerSurface || mDragResizeListener == null) {
+            closeDragResizeListener();
+            mDragResizeListener = new DragResizeInputListener(
+                    mContext,
+                    mHandler,
+                    mChoreographer,
+                    mDisplay.getDisplayId(),
+                    mDecorationContainerSurface,
+                    mDragResizeCallback);
+        }
+
+        int touchSlop = ViewConfiguration.get(mResult.mRootView.getContext()).getScaledTouchSlop();
+        mDragDetector.setTouchSlop(touchSlop);
+
+        int resize_handle = mResult.mRootView.getResources()
+                .getDimensionPixelSize(R.dimen.freeform_resize_handle);
+        int resize_corner = mResult.mRootView.getResources()
+                .getDimensionPixelSize(R.dimen.freeform_resize_corner);
+        mDragResizeListener.setGeometry(
+                mResult.mWidth, mResult.mHeight, resize_handle, resize_corner, touchSlop);
+    }
+
+    /**
+     * Sets up listeners when a new root view is created.
+     */
+    private void setupRootView() {
+        View caption = mResult.mRootView.findViewById(R.id.caption);
+        caption.setOnTouchListener(mOnCaptionTouchListener);
+        View close = caption.findViewById(R.id.close_window);
+        close.setOnClickListener(mOnCaptionButtonClickListener);
+        View back = caption.findViewById(R.id.back_button);
+        back.setOnClickListener(mOnCaptionButtonClickListener);
+        View minimize = caption.findViewById(R.id.minimize_window);
+        minimize.setOnClickListener(mOnCaptionButtonClickListener);
+        View maximize = caption.findViewById(R.id.maximize_window);
+        maximize.setOnClickListener(mOnCaptionButtonClickListener);
+    }
+
+    void setCaptionColor(int captionColor) {
+        if (mResult.mRootView == null) {
+            return;
+        }
+
+        View caption = mResult.mRootView.findViewById(R.id.caption);
+        GradientDrawable captionDrawable = (GradientDrawable) caption.getBackground();
+        captionDrawable.setColor(captionColor);
+
+        int buttonTintColorRes =
+                Color.valueOf(captionColor).luminance() < 0.5
+                        ? R.color.decor_button_light_color
+                        : R.color.decor_button_dark_color;
+        ColorStateList buttonTintColor =
+                caption.getResources().getColorStateList(buttonTintColorRes, null /* theme */);
+
+        View back = caption.findViewById(R.id.back_button);
+        VectorDrawable backBackground = (VectorDrawable) back.getBackground();
+        backBackground.setTintList(buttonTintColor);
+
+        View minimize = caption.findViewById(R.id.minimize_window);
+        VectorDrawable minimizeBackground = (VectorDrawable) minimize.getBackground();
+        minimizeBackground.setTintList(buttonTintColor);
+
+        View maximize = caption.findViewById(R.id.maximize_window);
+        VectorDrawable maximizeBackground = (VectorDrawable) maximize.getBackground();
+        maximizeBackground.setTintList(buttonTintColor);
+
+        View close = caption.findViewById(R.id.close_window);
+        VectorDrawable closeBackground = (VectorDrawable) close.getBackground();
+        closeBackground.setTintList(buttonTintColor);
+    }
+
+    private void closeDragResizeListener() {
+        if (mDragResizeListener == null) {
+            return;
+        }
+        mDragResizeListener.close();
+        mDragResizeListener = null;
+    }
+
+    @Override
+    public void close() {
+        closeDragResizeListener();
+        super.close();
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java
index 00aab6733369..13b4a956e4e5 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java
@@ -27,17 +27,12 @@ import android.content.Context;
 import android.hardware.input.InputManager;
 import android.os.Handler;
 import android.os.Looper;
-import android.os.SystemClock;
-import android.util.Log;
 import android.util.SparseArray;
 import android.view.Choreographer;
 import android.view.InputChannel;
-import android.view.InputDevice;
 import android.view.InputEvent;
 import android.view.InputEventReceiver;
 import android.view.InputMonitor;
-import android.view.KeyCharacterMap;
-import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.view.SurfaceControl;
 import android.view.View;
@@ -55,7 +50,6 @@ import com.android.wm.shell.desktopmode.DesktopModeController;
 import com.android.wm.shell.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.desktopmode.DesktopTasksController;
 import com.android.wm.shell.freeform.FreeformTaskTransitionStarter;
-import com.android.wm.shell.transition.Transitions;
 
 import java.util.Optional;
 
@@ -85,6 +79,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             new SparseArray<>();
     private final DragStartListenerImpl mDragStartListener = new DragStartListenerImpl();
     private InputMonitorFactory mInputMonitorFactory;
+    private TaskOperations mTaskOperations;
 
     public DesktopModeWindowDecorViewModel(
             Context context,
@@ -136,7 +131,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
 
     @Override
     public void setFreeformTaskTransitionStarter(FreeformTaskTransitionStarter transitionStarter) {
-        mTransitionStarter = transitionStarter;
+        mTaskOperations = new TaskOperations(transitionStarter, mContext, mSyncQueue);
     }
 
     @Override
@@ -210,7 +205,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
         }
     }
 
-    private class CaptionTouchEventListener implements
+    private class DesktopModeTouchEventListener implements
             View.OnClickListener, View.OnTouchListener {
 
         private final int mTaskId;
@@ -220,7 +215,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
 
         private int mDragPointerId = -1;
 
-        private CaptionTouchEventListener(
+        private DesktopModeTouchEventListener(
                 RunningTaskInfo taskInfo,
                 DragResizeCallback dragResizeCallback,
                 DragDetector dragDetector) {
@@ -235,15 +230,9 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             DesktopModeWindowDecoration decoration = mWindowDecorByTaskId.get(mTaskId);
             final int id = v.getId();
             if (id == R.id.close_window) {
-                WindowContainerTransaction wct = new WindowContainerTransaction();
-                wct.removeTask(mTaskToken);
-                if (Transitions.ENABLE_SHELL_TRANSITIONS) {
-                    mTransitionStarter.startRemoveTransition(wct);
-                } else {
-                    mSyncQueue.queue(wct);
-                }
+                mTaskOperations.closeTask(mTaskToken);
             } else if (id == R.id.back_button) {
-                injectBackKey();
+                mTaskOperations.injectBackKey();
             } else if (id == R.id.caption_handle) {
                 decoration.createHandleMenu();
             } else if (id == R.id.desktop_button) {
@@ -258,25 +247,6 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             }
         }
 
-        private void injectBackKey() {
-            sendBackEvent(KeyEvent.ACTION_DOWN);
-            sendBackEvent(KeyEvent.ACTION_UP);
-        }
-
-        private void sendBackEvent(int action) {
-            final long when = SystemClock.uptimeMillis();
-            final KeyEvent ev = new KeyEvent(when, when, action, KeyEvent.KEYCODE_BACK,
-                    0 /* repeat */, 0 /* metaState */, KeyCharacterMap.VIRTUAL_KEYBOARD,
-                    0 /* scancode */, KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,
-                    InputDevice.SOURCE_KEYBOARD);
-
-            ev.setDisplayId(mContext.getDisplay().getDisplayId());
-            if (!InputManager.getInstance()
-                    .injectInputEvent(ev, InputManager.INJECT_INPUT_EVENT_MODE_ASYNC)) {
-                Log.e(TAG, "Inject input event fail");
-            }
-        }
-
         @Override
         public boolean onTouch(View v, MotionEvent e) {
             boolean isDrag = false;
@@ -590,8 +560,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
 
         TaskPositioner taskPositioner =
                 new TaskPositioner(mTaskOrganizer, windowDecoration, mDragStartListener);
-        CaptionTouchEventListener touchEventListener =
-                new CaptionTouchEventListener(
+        DesktopModeTouchEventListener touchEventListener =
+                new DesktopModeTouchEventListener(
                         taskInfo, taskPositioner, windowDecoration.getDragDetector());
         windowDecoration.setCaptionListeners(touchEventListener, touchEventListener);
         windowDecoration.setDragResizeCallback(taskPositioner);
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskOperations.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskOperations.java
new file mode 100644
index 000000000000..aea340464304
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskOperations.java
@@ -0,0 +1,112 @@
+/*
+ * 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 static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
+import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
+import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
+
+import android.app.ActivityManager.RunningTaskInfo;
+import android.content.Context;
+import android.hardware.input.InputManager;
+import android.os.SystemClock;
+import android.util.Log;
+import android.view.InputDevice;
+import android.view.KeyCharacterMap;
+import android.view.KeyEvent;
+import android.window.WindowContainerToken;
+import android.window.WindowContainerTransaction;
+
+import com.android.wm.shell.common.SyncTransactionQueue;
+import com.android.wm.shell.freeform.FreeformTaskTransitionStarter;
+import com.android.wm.shell.transition.Transitions;
+
+/**
+ * Utility class to handle task operations performed on a window decoration.
+ */
+class TaskOperations {
+    private static final String TAG = "TaskOperations";
+
+    private final FreeformTaskTransitionStarter mTransitionStarter;
+    private final Context mContext;
+    private final SyncTransactionQueue mSyncQueue;
+
+    TaskOperations(FreeformTaskTransitionStarter transitionStarter, Context context,
+            SyncTransactionQueue syncQueue) {
+        mTransitionStarter = transitionStarter;
+        mContext = context;
+        mSyncQueue = syncQueue;
+    }
+
+    void injectBackKey() {
+        sendBackEvent(KeyEvent.ACTION_DOWN);
+        sendBackEvent(KeyEvent.ACTION_UP);
+    }
+
+    private void sendBackEvent(int action) {
+        final long when = SystemClock.uptimeMillis();
+        final KeyEvent ev = new KeyEvent(when, when, action, KeyEvent.KEYCODE_BACK,
+                0 /* repeat */, 0 /* metaState */, KeyCharacterMap.VIRTUAL_KEYBOARD,
+                0 /* scancode */, KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,
+                InputDevice.SOURCE_KEYBOARD);
+
+        ev.setDisplayId(mContext.getDisplay().getDisplayId());
+        if (!InputManager.getInstance()
+                .injectInputEvent(ev, InputManager.INJECT_INPUT_EVENT_MODE_ASYNC)) {
+            Log.e(TAG, "Inject input event fail");
+        }
+    }
+
+    void closeTask(WindowContainerToken taskToken) {
+        WindowContainerTransaction wct = new WindowContainerTransaction();
+        wct.removeTask(taskToken);
+        if (Transitions.ENABLE_SHELL_TRANSITIONS) {
+            mTransitionStarter.startRemoveTransition(wct);
+        } else {
+            mSyncQueue.queue(wct);
+        }
+    }
+
+    void minimizeTask(WindowContainerToken taskToken) {
+        WindowContainerTransaction wct = new WindowContainerTransaction();
+        wct.reorder(taskToken, false);
+        if (Transitions.ENABLE_SHELL_TRANSITIONS) {
+            mTransitionStarter.startMinimizedModeTransition(wct);
+        } else {
+            mSyncQueue.queue(wct);
+        }
+    }
+
+    void maximizeTask(RunningTaskInfo taskInfo) {
+        WindowContainerTransaction wct = new WindowContainerTransaction();
+        int targetWindowingMode = taskInfo.getWindowingMode() != WINDOWING_MODE_FULLSCREEN
+                ? WINDOWING_MODE_FULLSCREEN : WINDOWING_MODE_FREEFORM;
+        int displayWindowingMode =
+                taskInfo.configuration.windowConfiguration.getDisplayWindowingMode();
+        wct.setWindowingMode(taskInfo.token,
+                targetWindowingMode == displayWindowingMode
+                        ? WINDOWING_MODE_UNDEFINED : targetWindowingMode);
+        if (targetWindowingMode == WINDOWING_MODE_FULLSCREEN) {
+            wct.setBounds(taskInfo.token, null);
+        }
+        if (Transitions.ENABLE_SHELL_TRANSITIONS) {
+            mTransitionStarter.startWindowingModeTransition(targetWindowingMode, wct);
+        } else {
+            mSyncQueue.queue(wct);
+        }
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskPositioner.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskPositioner.java
index a49a300995e6..20631f85453f 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskPositioner.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskPositioner.java
@@ -47,6 +47,10 @@ class TaskPositioner implements DragResizeCallback {
     private int mCtrlType;
     private DragStartListener mDragStartListener;
 
+    TaskPositioner(ShellTaskOrganizer taskOrganizer, WindowDecoration windowDecoration) {
+        this(taskOrganizer, windowDecoration, dragStartListener -> {});
+    }
+
     TaskPositioner(ShellTaskOrganizer taskOrganizer, WindowDecoration windowDecoration,
             DragStartListener dragStartListener) {
         mTaskOrganizer = taskOrganizer;