Copyright (c) 2017 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.
/**
 * Copyright (c) 2017 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 android.app;

import android.annotation.NonNull;
import android.app.ActivityManager.StackInfo;
import android.content.Context;
import android.content.Intent;
import android.hardware.display.DisplayManager;
import android.hardware.display.VirtualDisplay;
import android.hardware.input.InputManager;
import android.os.RemoteException;
import android.os.UserHandle;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.IWindowManager;
import android.view.InputDevice;
import android.view.InputEvent;
import android.view.MotionEvent;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.view.WindowManagerGlobal;

import dalvik.system.CloseGuard;

import java.util.List;

Activity container that allows launching activities into itself and does input forwarding.
Creation of this view is only allowed to callers who have INJECT_EVENTS.INJECT_EVENTS permission. 
Activity launching into this container is restricted by the same rules that apply to launching
on VirtualDisplays.
@hide
/**
 * Activity container that allows launching activities into itself and does input forwarding.
 * <p>Creation of this view is only allowed to callers who have
 * {@link android.Manifest.permission#INJECT_EVENTS} permission.
 * <p>Activity launching into this container is restricted by the same rules that apply to launching
 * on VirtualDisplays.
 * @hide
 */
public class ActivityView extends ViewGroup {

    private static final String DISPLAY_NAME = "ActivityViewVirtualDisplay";
    private static final String TAG = "ActivityView";

    private VirtualDisplay mVirtualDisplay;
    private final SurfaceView mSurfaceView;
    private Surface mSurface;

    private final SurfaceCallback mSurfaceCallback;
    private StateCallback mActivityViewCallback;

    private IActivityManager mActivityManager;
    private IInputForwarder mInputForwarder;
    // Temp container to store view coordinates on screen.
    private final int[] mLocationOnScreen = new int[2];

    private TaskStackListener mTaskStackListener;

    private final CloseGuard mGuard = CloseGuard.get();
    private boolean mOpened; // Protected by mGuard.

    public ActivityView(Context context) {
        this(context, null /* attrs */);
    }

    public ActivityView(Context context, AttributeSet attrs) {
        this(context, attrs, 0 /* defStyle */);
    }

    public ActivityView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        mActivityManager = ActivityManager.getService();
        mSurfaceView = new SurfaceView(context);
        mSurfaceCallback = new SurfaceCallback();
        mSurfaceView.getHolder().addCallback(mSurfaceCallback);
        addView(mSurfaceView);

        mOpened = true;
        mGuard.open("release");
    }

    
Callback that notifies when the container is ready or destroyed. /** Callback that notifies when the container is ready or destroyed. */
    public abstract static class StateCallback {
        
Called when the container is ready for launching activities. Calling ActivityView.startActivity(Intent) prior to this callback will result in an IllegalStateException. 
See Also:
ActivityView.startActivity(Intent)/**
         * Called when the container is ready for launching activities. Calling
         * {@link #startActivity(Intent)} prior to this callback will result in an
         * {@link IllegalStateException}.
         *
         * @see #startActivity(Intent)
         */
        public abstract void onActivityViewReady(ActivityView view);
        
Called when the container can no longer launch activities. Calling ActivityView.startActivity(Intent) after this callback will result in an IllegalStateException. 
See Also:
ActivityView.startActivity(Intent)/**
         * Called when the container can no longer launch activities. Calling
         * {@link #startActivity(Intent)} after this callback will result in an
         * {@link IllegalStateException}.
         *
         * @see #startActivity(Intent)
         */
        public abstract void onActivityViewDestroyed(ActivityView view);
        
Called when a task is moved to the front of the stack inside the container. This is a filtered version of TaskStackListener /**
         * Called when a task is moved to the front of the stack inside the container.
         * This is a filtered version of {@link TaskStackListener}
         */
        public void onTaskMovedToFront(ActivityManager.StackInfo stackInfo) { }
    }

    
Set the callback to be notified about state changes.
This class must finish initializing before startActivity(Intent) can be called. 
Note: If the instance was ready prior to this call being made, then StateCallback.onActivityViewReady(ActivityView) will be called from within this method call. 
Params:
callback – The callback to report events to.
See Also:
StateCallback
startActivity(Intent)/**
     * Set the callback to be notified about state changes.
     * <p>This class must finish initializing before {@link #startActivity(Intent)} can be called.
     * <p>Note: If the instance was ready prior to this call being made, then
     * {@link StateCallback#onActivityViewReady(ActivityView)} will be called from within
     * this method call.
     *
     * @param callback The callback to report events to.
     *
     * @see StateCallback
     * @see #startActivity(Intent)
     */
    public void setCallback(StateCallback callback) {
        mActivityViewCallback = callback;

        if (mVirtualDisplay != null && mActivityViewCallback != null) {
            mActivityViewCallback.onActivityViewReady(this);
        }
    }

    
Launch a new activity into this container.
Activity resolved by the provided Intent must have resizeableActivity.resizeableActivity attribute set to true in order to be launched here. Also, if activity is not owned by the owner of this container, it must allow embedding and the caller must have permission to embed. 
Note: This class must finish initializing and StateCallback.onActivityViewReady(ActivityView) callback must be triggered before this method can be called. 
Params:
intent – Intent used to launch an activity.
See Also:
StateCallback
startActivity(PendingIntent)/**
     * Launch a new activity into this container.
     * <p>Activity resolved by the provided {@link Intent} must have
     * {@link android.R.attr#resizeableActivity} attribute set to {@code true} in order to be
     * launched here. Also, if activity is not owned by the owner of this container, it must allow
     * embedding and the caller must have permission to embed.
     * <p>Note: This class must finish initializing and
     * {@link StateCallback#onActivityViewReady(ActivityView)} callback must be triggered before
     * this method can be called.
     *
     * @param intent Intent used to launch an activity.
     *
     * @see StateCallback
     * @see #startActivity(PendingIntent)
     */
    public void startActivity(@NonNull Intent intent) {
        final ActivityOptions options = prepareActivityOptions();
        getContext().startActivity(intent, options.toBundle());
    }

    
Launch a new activity into this container.
Activity resolved by the provided Intent must have resizeableActivity.resizeableActivity attribute set to true in order to be launched here. Also, if activity is not owned by the owner of this container, it must allow embedding and the caller must have permission to embed. 
Note: This class must finish initializing and StateCallback.onActivityViewReady(ActivityView) callback must be triggered before this method can be called. 
Params:
intent – Intent used to launch an activity.
user – The UserHandle of the user to start this activity for.
See Also:
StateCallback
startActivity(PendingIntent)/**
     * Launch a new activity into this container.
     * <p>Activity resolved by the provided {@link Intent} must have
     * {@link android.R.attr#resizeableActivity} attribute set to {@code true} in order to be
     * launched here. Also, if activity is not owned by the owner of this container, it must allow
     * embedding and the caller must have permission to embed.
     * <p>Note: This class must finish initializing and
     * {@link StateCallback#onActivityViewReady(ActivityView)} callback must be triggered before
     * this method can be called.
     *
     * @param intent Intent used to launch an activity.
     * @param user The UserHandle of the user to start this activity for.
     *
     *
     * @see StateCallback
     * @see #startActivity(PendingIntent)
     */
    public void startActivity(@NonNull Intent intent, UserHandle user) {
        final ActivityOptions options = prepareActivityOptions();
        getContext().startActivityAsUser(intent, options.toBundle(), user);
    }

    
Launch a new activity into this container.
Activity resolved by the provided PendingIntent must have resizeableActivity.resizeableActivity attribute set to true in order to be launched here. Also, if activity is not owned by the owner of this container, it must allow embedding and the caller must have permission to embed. 
Note: This class must finish initializing and StateCallback.onActivityViewReady(ActivityView) callback must be triggered before this method can be called. 
Params:
pendingIntent – Intent used to launch an activity.
See Also:
StateCallback
startActivity(Intent)/**
     * Launch a new activity into this container.
     * <p>Activity resolved by the provided {@link PendingIntent} must have
     * {@link android.R.attr#resizeableActivity} attribute set to {@code true} in order to be
     * launched here. Also, if activity is not owned by the owner of this container, it must allow
     * embedding and the caller must have permission to embed.
     * <p>Note: This class must finish initializing and
     * {@link StateCallback#onActivityViewReady(ActivityView)} callback must be triggered before
     * this method can be called.
     *
     * @param pendingIntent Intent used to launch an activity.
     *
     * @see StateCallback
     * @see #startActivity(Intent)
     */
    public void startActivity(@NonNull PendingIntent pendingIntent) {
        final ActivityOptions options = prepareActivityOptions();
        try {
            pendingIntent.send(null /* context */, 0 /* code */, null /* intent */,
                    null /* onFinished */, null /* handler */, null /* requiredPermission */,
                    options.toBundle());
        } catch (PendingIntent.CanceledException e) {
            throw new RuntimeException(e);
        }
    }

    
Check if container is ready to launch and create ActivityOptions to target the virtual display. /**
     * Check if container is ready to launch and create {@link ActivityOptions} to target the
     * virtual display.
     */
    private ActivityOptions prepareActivityOptions() {
        if (mVirtualDisplay == null) {
            throw new IllegalStateException(
                    "Trying to start activity before ActivityView is ready.");
        }
        final ActivityOptions options = ActivityOptions.makeBasic();
        options.setLaunchDisplayId(mVirtualDisplay.getDisplay().getDisplayId());
        return options;
    }

    
Release this container. Activity launching will no longer be permitted.
Note: Calling this method is allowed after StateCallback.onActivityViewReady(ActivityView) callback was triggered and before StateCallback.onActivityViewDestroyed(ActivityView). 
See Also:
StateCallback/**
     * Release this container. Activity launching will no longer be permitted.
     * <p>Note: Calling this method is allowed after
     * {@link StateCallback#onActivityViewReady(ActivityView)} callback was triggered and before
     * {@link StateCallback#onActivityViewDestroyed(ActivityView)}.
     *
     * @see StateCallback
     */
    public void release() {
        if (mVirtualDisplay == null) {
            throw new IllegalStateException(
                    "Trying to release container that is not initialized.");
        }
        performRelease();
    }

    
Triggers an update of ActivityView's location on screen to properly set touch exclude regions and avoid focus switches by touches on this view. /**
     * Triggers an update of {@link ActivityView}'s location on screen to properly set touch exclude
     * regions and avoid focus switches by touches on this view.
     */
    public void onLocationChanged() {
        updateLocation();
    }

    @Override
    public void onLayout(boolean changed, int l, int t, int r, int b) {
        mSurfaceView.layout(0 /* left */, 0 /* top */, r - l /* right */, b - t /* bottom */);
    }

    
Send current location and size to the WM to set tap exclude region for this view. /** Send current location and size to the WM to set tap exclude region for this view. */
    private void updateLocation() {
        try {
            getLocationOnScreen(mLocationOnScreen);
            WindowManagerGlobal.getWindowSession().updateTapExcludeRegion(getWindow(), hashCode(),
                    mLocationOnScreen[0], mLocationOnScreen[1], getWidth(), getHeight());
        } catch (RemoteException e) {
            e.rethrowAsRuntimeException();
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return injectInputEvent(event) || super.onTouchEvent(event);
    }

    @Override
    public boolean onGenericMotionEvent(MotionEvent event) {
        if (event.isFromSource(InputDevice.SOURCE_CLASS_POINTER)) {
            if (injectInputEvent(event)) {
                return true;
            }
        }
        return super.onGenericMotionEvent(event);
    }

    private boolean injectInputEvent(InputEvent event) {
        if (mInputForwarder != null) {
            try {
                return mInputForwarder.forwardEvent(event);
            } catch (RemoteException e) {
                e.rethrowAsRuntimeException();
            }
        }
        return false;
    }

    private class SurfaceCallback implements SurfaceHolder.Callback {
        @Override
        public void surfaceCreated(SurfaceHolder surfaceHolder) {
            mSurface = mSurfaceView.getHolder().getSurface();
            if (mVirtualDisplay == null) {
                initVirtualDisplay();
                if (mVirtualDisplay != null && mActivityViewCallback != null) {
                    mActivityViewCallback.onActivityViewReady(ActivityView.this);
                }
            } else {
                mVirtualDisplay.setSurface(surfaceHolder.getSurface());
            }
            updateLocation();
        }

        @Override
        public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) {
            if (mVirtualDisplay != null) {
                mVirtualDisplay.resize(width, height, getBaseDisplayDensity());
            }
            updateLocation();
        }

        @Override
        public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
            mSurface.release();
            mSurface = null;
            if (mVirtualDisplay != null) {
                mVirtualDisplay.setSurface(null);
            }
            cleanTapExcludeRegion();
        }
    }

    private void initVirtualDisplay() {
        if (mVirtualDisplay != null) {
            throw new IllegalStateException("Trying to initialize for the second time.");
        }

        final int width = mSurfaceView.getWidth();
        final int height = mSurfaceView.getHeight();
        final DisplayManager displayManager = mContext.getSystemService(DisplayManager.class);
        mVirtualDisplay = displayManager.createVirtualDisplay(
                DISPLAY_NAME + "@" + System.identityHashCode(this),
                width, height, getBaseDisplayDensity(), mSurface,
                DisplayManager.VIRTUAL_DISPLAY_FLAG_PUBLIC
                        | DisplayManager.VIRTUAL_DISPLAY_FLAG_OWN_CONTENT_ONLY);
        if (mVirtualDisplay == null) {
            Log.e(TAG, "Failed to initialize ActivityView");
            return;
        }

        final int displayId = mVirtualDisplay.getDisplay().getDisplayId();
        final IWindowManager wm = WindowManagerGlobal.getWindowManagerService();
        try {
            wm.dontOverrideDisplayInfo(displayId);
        } catch (RemoteException e) {
            e.rethrowAsRuntimeException();
        }
        mInputForwarder = InputManager.getInstance().createInputForwarder(displayId);
        mTaskStackListener = new TaskStackListenerImpl();
        try {
            mActivityManager.registerTaskStackListener(mTaskStackListener);
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to register task stack listener", e);
        }
    }

    private void performRelease() {
        if (!mOpened) {
            return;
        }

        mSurfaceView.getHolder().removeCallback(mSurfaceCallback);

        if (mInputForwarder != null) {
            mInputForwarder = null;
        }
        cleanTapExcludeRegion();

        if (mTaskStackListener != null) {
            try {
                mActivityManager.unregisterTaskStackListener(mTaskStackListener);
            } catch (RemoteException e) {
                Log.e(TAG, "Failed to unregister task stack listener", e);
            }
            mTaskStackListener = null;
        }

        final boolean displayReleased;
        if (mVirtualDisplay != null) {
            mVirtualDisplay.release();
            mVirtualDisplay = null;
            displayReleased = true;
        } else {
            displayReleased = false;
        }

        if (mSurface != null) {
            mSurface.release();
            mSurface = null;
        }

        if (displayReleased && mActivityViewCallback != null) {
            mActivityViewCallback.onActivityViewDestroyed(this);
        }

        mGuard.close();
        mOpened = false;
    }

    
Report to server that tap exclude region on hosting display should be cleared. /** Report to server that tap exclude region on hosting display should be cleared. */
    private void cleanTapExcludeRegion() {
        // Update tap exclude region with an empty rect to clean the state on server.
        try {
            WindowManagerGlobal.getWindowSession().updateTapExcludeRegion(getWindow(), hashCode(),
                    0 /* left */, 0 /* top */, 0 /* width */, 0 /* height */);
        } catch (RemoteException e) {
            e.rethrowAsRuntimeException();
        }
    }

    
Get density of the hosting display. /** Get density of the hosting display. */
    private int getBaseDisplayDensity() {
        final WindowManager wm = mContext.getSystemService(WindowManager.class);
        final DisplayMetrics metrics = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(metrics);
        return metrics.densityDpi;
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            if (mGuard != null) {
                mGuard.warnIfOpen();
                performRelease();
            }
        } finally {
            super.finalize();
        }
    }

    
A task change listener that detects background color change of the topmost stack on our virtual display and updates the background of the surface view. This background will be shown when surface view is resized, but the app hasn't drawn its content in new size yet. It also calls StateCallback.onTaskMovedToFront to notify interested parties that the stack associated with the ActivityView has had a Task moved to the front. This is useful when needing to also bring the host Activity to the foreground at the same time. /**
     * A task change listener that detects background color change of the topmost stack on our
     * virtual display and updates the background of the surface view. This background will be shown
     * when surface view is resized, but the app hasn't drawn its content in new size yet.
     * It also calls StateCallback.onTaskMovedToFront to notify interested parties that the stack
     * associated with the {@link ActivityView} has had a Task moved to the front. This is useful
     * when needing to also bring the host Activity to the foreground at the same time.
     */
    private class TaskStackListenerImpl extends TaskStackListener {

        @Override
        public void onTaskDescriptionChanged(int taskId, ActivityManager.TaskDescription td)
                throws RemoteException {
            if (mVirtualDisplay == null) {
                return;
            }

            StackInfo stackInfo = getTopMostStackInfo();
            if (stackInfo == null) {
                return;
            }
            // Found the topmost stack on target display. Now check if the topmost task's
            // description changed.
            if (taskId == stackInfo.taskIds[stackInfo.taskIds.length - 1]) {
                mSurfaceView.setResizeBackgroundColor(td.getBackgroundColor());
            }
        }

        @Override
        public void onTaskMovedToFront(int taskId) throws RemoteException {
            if (mActivityViewCallback  != null) {
                StackInfo stackInfo = getTopMostStackInfo();
                // if StackInfo was null or unrelated to the "move to front" then there's no use
                // notifying the callback
                if (stackInfo != null
                        && taskId == stackInfo.taskIds[stackInfo.taskIds.length - 1]) {
                    mActivityViewCallback.onTaskMovedToFront(stackInfo);
                }
            }
        }

        private StackInfo getTopMostStackInfo() throws RemoteException {
            // Find the topmost task on our virtual display - it will define the background
            // color of the surface view during resizing.
            final int displayId = mVirtualDisplay.getDisplay().getDisplayId();
            final List<StackInfo> stackInfoList = mActivityManager.getAllStackInfos();

            // Iterate through stacks from top to bottom.
            final int stackCount = stackInfoList.size();
            for (int i = 0; i < stackCount; i++) {
                final StackInfo stackInfo = stackInfoList.get(i);
                // Only look for stacks on our virtual display.
                if (stackInfo.displayId != displayId) {
                    continue;
                }
                // Found the topmost stack on target display.
                return stackInfo;
            }
            return null;
        }
    }
}