https://source.android.com/ 
/*
 * Copyright (C) 2006 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.view;

import static android.view.WindowManagerPolicyConstants.APPLICATION_MEDIA_OVERLAY_SUBLAYER;
import static android.view.WindowManagerPolicyConstants.APPLICATION_MEDIA_SUBLAYER;
import static android.view.WindowManagerPolicyConstants.APPLICATION_PANEL_SUBLAYER;

import android.content.Context;
import android.content.res.CompatibilityInfo.Translator;
import android.content.res.Configuration;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.graphics.Rect;
import android.graphics.Region;
import android.os.Build;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.util.Log;

import com.android.internal.view.SurfaceCallbackHelper;

import java.util.ArrayList;
import java.util.concurrent.locks.ReentrantLock;


Provides a dedicated drawing surface embedded inside of a view hierarchy.
You can control the format of this surface and, if you like, its size; the
SurfaceView takes care of placing the surface at the correct location on the
screen

The surface is Z ordered so that it is behind the window holding its
SurfaceView; the SurfaceView punches a hole in its window to allow its
surface to be displayed. The view hierarchy will take care of correctly
compositing with the Surface any siblings of the SurfaceView that would
normally appear on top of it. This can be used to place overlays such as
buttons on top of the Surface, though note however that it can have an
impact on performance since a full alpha-blended composite will be performed
each time the Surface changes.

 The transparent region that makes the surface visible is based on the
layout positions in the view hierarchy. If the post-layout transform
properties are used to draw a sibling view on top of the SurfaceView, the
view may not be properly composited with the surface.

Access to the underlying surface is provided via the SurfaceHolder interface, which can be retrieved by calling getHolder. 
The Surface will be created for you while the SurfaceView's window is visible; you should implement Callback.surfaceCreated and Callback.surfaceDestroyed to discover when the Surface is created and destroyed as the window is shown and hidden. 
One of the purposes of this class is to provide a surface in which a
secondary thread can render into the screen. If you are going to use it
this way, you need to be aware of some threading semantics:



Note: Starting in platform version VERSION_CODES.N, SurfaceView's window position is updated synchronously with other View rendering. This means that translating and scaling a SurfaceView on screen will not cause rendering artifacts. Such artifacts may occur on previous versions of the platform when its window is positioned asynchronously.


/**
 * Provides a dedicated drawing surface embedded inside of a view hierarchy.
 * You can control the format of this surface and, if you like, its size; the
 * SurfaceView takes care of placing the surface at the correct location on the
 * screen
 *
 * <p>The surface is Z ordered so that it is behind the window holding its
 * SurfaceView; the SurfaceView punches a hole in its window to allow its
 * surface to be displayed. The view hierarchy will take care of correctly
 * compositing with the Surface any siblings of the SurfaceView that would
 * normally appear on top of it. This can be used to place overlays such as
 * buttons on top of the Surface, though note however that it can have an
 * impact on performance since a full alpha-blended composite will be performed
 * each time the Surface changes.
 *
 * <p> The transparent region that makes the surface visible is based on the
 * layout positions in the view hierarchy. If the post-layout transform
 * properties are used to draw a sibling view on top of the SurfaceView, the
 * view may not be properly composited with the surface.
 *
 * <p>Access to the underlying surface is provided via the SurfaceHolder interface,
 * which can be retrieved by calling {@link #getHolder}.
 *
 * <p>The Surface will be created for you while the SurfaceView's window is
 * visible; you should implement {@link SurfaceHolder.Callback#surfaceCreated}
 * and {@link SurfaceHolder.Callback#surfaceDestroyed} to discover when the
 * Surface is created and destroyed as the window is shown and hidden.
 *
 * <p>One of the purposes of this class is to provide a surface in which a
 * secondary thread can render into the screen. If you are going to use it
 * this way, you need to be aware of some threading semantics:
 *
 * <ul>
 * <li> All SurfaceView and
 * {@link SurfaceHolder.Callback SurfaceHolder.Callback} methods will be called
 * from the thread running the SurfaceView's window (typically the main thread
 * of the application). They thus need to correctly synchronize with any
 * state that is also touched by the drawing thread.
 * <li> You must ensure that the drawing thread only touches the underlying
 * Surface while it is valid -- between
 * {@link SurfaceHolder.Callback#surfaceCreated SurfaceHolder.Callback.surfaceCreated()}
 * and
 * {@link SurfaceHolder.Callback#surfaceDestroyed SurfaceHolder.Callback.surfaceDestroyed()}.
 * </ul>
 *
 * <p class="note"><strong>Note:</strong> Starting in platform version
 * {@link android.os.Build.VERSION_CODES#N}, SurfaceView's window position is
 * updated synchronously with other View rendering. This means that translating
 * and scaling a SurfaceView on screen will not cause rendering artifacts. Such
 * artifacts may occur on previous versions of the platform when its window is
 * positioned asynchronously.</p>
 */
public class SurfaceView extends View implements ViewRootImpl.WindowStoppedCallback {
    private static final String TAG = "SurfaceView";
    private static final boolean DEBUG = false;

    final ArrayList<SurfaceHolder.Callback> mCallbacks
            = new ArrayList<SurfaceHolder.Callback>();

    final int[] mLocation = new int[2];

    final ReentrantLock mSurfaceLock = new ReentrantLock();
    final Surface mSurface = new Surface();       // Current surface in use
    boolean mDrawingStopped = true;
    // We use this to track if the application has produced a frame
    // in to the Surface. Up until that point, we should be careful not to punch
    // holes.
    boolean mDrawFinished = false;

    final Rect mScreenRect = new Rect();
    SurfaceSession mSurfaceSession;

    SurfaceControlWithBackground mSurfaceControl;
    // In the case of format changes we switch out the surface in-place
    // we need to preserve the old one until the new one has drawn.
    SurfaceControl mDeferredDestroySurfaceControl;
    final Rect mTmpRect = new Rect();
    final Configuration mConfiguration = new Configuration();

    int mSubLayer = APPLICATION_MEDIA_SUBLAYER;

    boolean mIsCreating = false;
    private volatile boolean mRtHandlingPositionUpdates = false;

    private final ViewTreeObserver.OnScrollChangedListener mScrollChangedListener
            = new ViewTreeObserver.OnScrollChangedListener() {
                    @Override
                    public void onScrollChanged() {
                        updateSurface();
                    }
            };

    private final ViewTreeObserver.OnPreDrawListener mDrawListener =
            new ViewTreeObserver.OnPreDrawListener() {
                @Override
                public boolean onPreDraw() {
                    // reposition ourselves where the surface is
                    mHaveFrame = getWidth() > 0 && getHeight() > 0;
                    updateSurface();
                    return true;
                }
            };

    boolean mRequestedVisible = false;
    boolean mWindowVisibility = false;
    boolean mLastWindowVisibility = false;
    boolean mViewVisibility = false;
    boolean mWindowStopped = false;

    int mRequestedWidth = -1;
    int mRequestedHeight = -1;
    /* Set SurfaceView's format to 565 by default to maintain backward
     * compatibility with applications assuming this format.
     */
    int mRequestedFormat = PixelFormat.RGB_565;

    boolean mHaveFrame = false;
    boolean mSurfaceCreated = false;
    long mLastLockTime = 0;

    boolean mVisible = false;
    int mWindowSpaceLeft = -1;
    int mWindowSpaceTop = -1;
    int mSurfaceWidth = -1;
    int mSurfaceHeight = -1;
    int mFormat = -1;
    final Rect mSurfaceFrame = new Rect();
    int mLastSurfaceWidth = -1, mLastSurfaceHeight = -1;
    private Translator mTranslator;

    private boolean mGlobalListenersAdded;
    private boolean mAttachedToWindow;

    private int mSurfaceFlags = SurfaceControl.HIDDEN;

    private int mPendingReportDraws;

    private SurfaceControl.Transaction mRtTransaction = new SurfaceControl.Transaction();

    public SurfaceView(Context context) {
        this(context, null);
    }

    public SurfaceView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public SurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public SurfaceView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        mRenderNode.requestPositionUpdates(this);

        setWillNotDraw(true);
    }

    
Return the SurfaceHolder providing access and control over this
SurfaceView's underlying surface.

Returns:SurfaceHolder The holder of the surface.
/**
     * Return the SurfaceHolder providing access and control over this
     * SurfaceView's underlying surface.
     *
     * @return SurfaceHolder The holder of the surface.
     */
    public SurfaceHolder getHolder() {
        return mSurfaceHolder;
    }

    private void updateRequestedVisibility() {
        mRequestedVisible = mViewVisibility && mWindowVisibility && !mWindowStopped;
    }

    
@hide
/** @hide */
    @Override
    public void windowStopped(boolean stopped) {
        mWindowStopped = stopped;
        updateRequestedVisibility();
        updateSurface();
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();

        getViewRootImpl().addWindowStoppedCallback(this);
        mWindowStopped = false;

        mViewVisibility = getVisibility() == VISIBLE;
        updateRequestedVisibility();

        mAttachedToWindow = true;
        mParent.requestTransparentRegion(SurfaceView.this);
        if (!mGlobalListenersAdded) {
            ViewTreeObserver observer = getViewTreeObserver();
            observer.addOnScrollChangedListener(mScrollChangedListener);
            observer.addOnPreDrawListener(mDrawListener);
            mGlobalListenersAdded = true;
        }
    }

    @Override
    protected void onWindowVisibilityChanged(int visibility) {
        super.onWindowVisibilityChanged(visibility);
        mWindowVisibility = visibility == VISIBLE;
        updateRequestedVisibility();
        updateSurface();
    }

    @Override
    public void setVisibility(int visibility) {
        super.setVisibility(visibility);
        mViewVisibility = visibility == VISIBLE;
        boolean newRequestedVisible = mWindowVisibility && mViewVisibility && !mWindowStopped;
        if (newRequestedVisible != mRequestedVisible) {
            // our base class (View) invalidates the layout only when
            // we go from/to the GONE state. However, SurfaceView needs
            // to request a re-layout when the visibility changes at all.
            // This is needed because the transparent region is computed
            // as part of the layout phase, and it changes (obviously) when
            // the visibility changes.
            requestLayout();
        }
        mRequestedVisible = newRequestedVisible;
        updateSurface();
    }

    private void performDrawFinished() {
        if (mPendingReportDraws > 0) {
            mDrawFinished = true;
            if (mAttachedToWindow) {
                notifyDrawFinished();
                invalidate();
            }
        } else {
            Log.e(TAG, System.identityHashCode(this) + "finished drawing"
                    + " but no pending report draw (extra call"
                    + " to draw completion runnable?)");
        }
    }

    void notifyDrawFinished() {
        ViewRootImpl viewRoot = getViewRootImpl();
        if (viewRoot != null) {
            viewRoot.pendingDrawFinished();
        }
        mPendingReportDraws--;
    }

    @Override
    protected void onDetachedFromWindow() {
        ViewRootImpl viewRoot = getViewRootImpl();
        // It's possible to create a SurfaceView using the default constructor and never
        // attach it to a view hierarchy, this is a common use case when dealing with
        // OpenGL. A developer will probably create a new GLSurfaceView, and let it manage
        // the lifecycle. Instead of attaching it to a view, he/she can just pass
        // the SurfaceHolder forward, most live wallpapers do it.
        if (viewRoot != null) {
            viewRoot.removeWindowStoppedCallback(this);
        }

        mAttachedToWindow = false;
        if (mGlobalListenersAdded) {
            ViewTreeObserver observer = getViewTreeObserver();
            observer.removeOnScrollChangedListener(mScrollChangedListener);
            observer.removeOnPreDrawListener(mDrawListener);
            mGlobalListenersAdded = false;
        }

        while (mPendingReportDraws > 0) {
            notifyDrawFinished();
        }

        mRequestedVisible = false;

        updateSurface();
        if (mSurfaceControl != null) {
            mSurfaceControl.destroy();
        }
        mSurfaceControl = null;

        mHaveFrame = false;

        super.onDetachedFromWindow();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int width = mRequestedWidth >= 0
                ? resolveSizeAndState(mRequestedWidth, widthMeasureSpec, 0)
                : getDefaultSize(0, widthMeasureSpec);
        int height = mRequestedHeight >= 0
                ? resolveSizeAndState(mRequestedHeight, heightMeasureSpec, 0)
                : getDefaultSize(0, heightMeasureSpec);
        setMeasuredDimension(width, height);
    }

    
@hide
/** @hide */
    @Override
    protected boolean setFrame(int left, int top, int right, int bottom) {
        boolean result = super.setFrame(left, top, right, bottom);
        updateSurface();
        return result;
    }

    @Override
    public boolean gatherTransparentRegion(Region region) {
        if (isAboveParent() || !mDrawFinished) {
            return super.gatherTransparentRegion(region);
        }

        boolean opaque = true;
        if ((mPrivateFlags & PFLAG_SKIP_DRAW) == 0) {
            // this view draws, remove it from the transparent region
            opaque = super.gatherTransparentRegion(region);
        } else if (region != null) {
            int w = getWidth();
            int h = getHeight();
            if (w>0 && h>0) {
                getLocationInWindow(mLocation);
                // otherwise, punch a hole in the whole hierarchy
                int l = mLocation[0];
                int t = mLocation[1];
                region.op(l, t, l+w, t+h, Region.Op.UNION);
            }
        }
        if (PixelFormat.formatHasAlpha(mRequestedFormat)) {
            opaque = false;
        }
        return opaque;
    }

    @Override
    public void draw(Canvas canvas) {
        if (mDrawFinished && !isAboveParent()) {
            // draw() is not called when SKIP_DRAW is set
            if ((mPrivateFlags & PFLAG_SKIP_DRAW) == 0) {
                // punch a whole in the view-hierarchy below us
                canvas.drawColor(0, PorterDuff.Mode.CLEAR);
            }
        }
        super.draw(canvas);
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        if (mDrawFinished && !isAboveParent()) {
            // draw() is not called when SKIP_DRAW is set
            if ((mPrivateFlags & PFLAG_SKIP_DRAW) == PFLAG_SKIP_DRAW) {
                // punch a whole in the view-hierarchy below us
                canvas.drawColor(0, PorterDuff.Mode.CLEAR);
            }
        }
        super.dispatchDraw(canvas);
    }

    
Control whether the surface view's surface is placed on top of another
regular surface view in the window (but still behind the window itself).
This is typically used to place overlays on top of an underlying media
surface view.

Note that this must be set before the surface view's containing
window is attached to the window manager.

Calling this overrides any previous call to setZOrderOnTop. 
/**
     * Control whether the surface view's surface is placed on top of another
     * regular surface view in the window (but still behind the window itself).
     * This is typically used to place overlays on top of an underlying media
     * surface view.
     *
     * <p>Note that this must be set before the surface view's containing
     * window is attached to the window manager.
     *
     * <p>Calling this overrides any previous call to {@link #setZOrderOnTop}.
     */
    public void setZOrderMediaOverlay(boolean isMediaOverlay) {
        mSubLayer = isMediaOverlay
            ? APPLICATION_MEDIA_OVERLAY_SUBLAYER : APPLICATION_MEDIA_SUBLAYER;
    }

    
Control whether the surface view's surface is placed on top of its
window.  Normally it is placed behind the window, to allow it to
(for the most part) appear to composite with the views in the
hierarchy.  By setting this, you cause it to be placed above the
window.  This means that none of the contents of the window this
SurfaceView is in will be visible on top of its surface.

Note that this must be set before the surface view's containing
window is attached to the window manager.

Calling this overrides any previous call to setZOrderMediaOverlay. 
/**
     * Control whether the surface view's surface is placed on top of its
     * window.  Normally it is placed behind the window, to allow it to
     * (for the most part) appear to composite with the views in the
     * hierarchy.  By setting this, you cause it to be placed above the
     * window.  This means that none of the contents of the window this
     * SurfaceView is in will be visible on top of its surface.
     *
     * <p>Note that this must be set before the surface view's containing
     * window is attached to the window manager.
     *
     * <p>Calling this overrides any previous call to {@link #setZOrderMediaOverlay}.
     */
    public void setZOrderOnTop(boolean onTop) {
        if (onTop) {
            mSubLayer = APPLICATION_PANEL_SUBLAYER;
        } else {
            mSubLayer = APPLICATION_MEDIA_SUBLAYER;
        }
    }

    
Control whether the surface view's content should be treated as secure,
preventing it from appearing in screenshots or from being viewed on
non-secure displays.

Note that this must be set before the surface view's containing
window is attached to the window manager.

See Display.FLAG_SECURE for details. 
Params:
  • isSecure – True if the surface view is secure.
/**
     * Control whether the surface view's content should be treated as secure,
     * preventing it from appearing in screenshots or from being viewed on
     * non-secure displays.
     *
     * <p>Note that this must be set before the surface view's containing
     * window is attached to the window manager.
     *
     * <p>See {@link android.view.Display#FLAG_SECURE} for details.
     *
     * @param isSecure True if the surface view is secure.
     */
    public void setSecure(boolean isSecure) {
        if (isSecure) {
            mSurfaceFlags |= SurfaceControl.SECURE;
        } else {
            mSurfaceFlags &= ~SurfaceControl.SECURE;
        }
    }

    private void updateOpaqueFlag() {
        if (!PixelFormat.formatHasAlpha(mRequestedFormat)) {
            mSurfaceFlags |= SurfaceControl.OPAQUE;
        } else {
            mSurfaceFlags &= ~SurfaceControl.OPAQUE;
        }
    }

    private Rect getParentSurfaceInsets() {
        final ViewRootImpl root = getViewRootImpl();
        if (root == null) {
            return null;
        } else {
            return root.mWindowAttributes.surfaceInsets;
        }
    }

    
@hide
/** @hide */
    protected void updateSurface() {
        if (!mHaveFrame) {
            return;
        }
        ViewRootImpl viewRoot = getViewRootImpl();
        if (viewRoot == null || viewRoot.mSurface == null || !viewRoot.mSurface.isValid()) {
            return;
        }

        mTranslator = viewRoot.mTranslator;
        if (mTranslator != null) {
            mSurface.setCompatibilityTranslator(mTranslator);
        }

        int myWidth = mRequestedWidth;
        if (myWidth <= 0) myWidth = getWidth();
        int myHeight = mRequestedHeight;
        if (myHeight <= 0) myHeight = getHeight();

        final boolean formatChanged = mFormat != mRequestedFormat;
        final boolean visibleChanged = mVisible != mRequestedVisible;
        final boolean creating = (mSurfaceControl == null || formatChanged || visibleChanged)
                && mRequestedVisible;
        final boolean sizeChanged = mSurfaceWidth != myWidth || mSurfaceHeight != myHeight;
        final boolean windowVisibleChanged = mWindowVisibility != mLastWindowVisibility;
        boolean redrawNeeded = false;

        if (creating || formatChanged || sizeChanged || visibleChanged || windowVisibleChanged) {
            getLocationInWindow(mLocation);

            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                    + "Changes: creating=" + creating
                    + " format=" + formatChanged + " size=" + sizeChanged
                    + " visible=" + visibleChanged
                    + " left=" + (mWindowSpaceLeft != mLocation[0])
                    + " top=" + (mWindowSpaceTop != mLocation[1]));

            try {
                final boolean visible = mVisible = mRequestedVisible;
                mWindowSpaceLeft = mLocation[0];
                mWindowSpaceTop = mLocation[1];
                mSurfaceWidth = myWidth;
                mSurfaceHeight = myHeight;
                mFormat = mRequestedFormat;
                mLastWindowVisibility = mWindowVisibility;

                mScreenRect.left = mWindowSpaceLeft;
                mScreenRect.top = mWindowSpaceTop;
                mScreenRect.right = mWindowSpaceLeft + getWidth();
                mScreenRect.bottom = mWindowSpaceTop + getHeight();
                if (mTranslator != null) {
                    mTranslator.translateRectInAppWindowToScreen(mScreenRect);
                }

                final Rect surfaceInsets = getParentSurfaceInsets();
                mScreenRect.offset(surfaceInsets.left, surfaceInsets.top);

                if (creating) {
                    mSurfaceSession = new SurfaceSession(viewRoot.mSurface);
                    mDeferredDestroySurfaceControl = mSurfaceControl;

                    updateOpaqueFlag();
                    final String name = "SurfaceView - " + viewRoot.getTitle().toString();

                    mSurfaceControl = new SurfaceControlWithBackground(
                            name,
                            (mSurfaceFlags & SurfaceControl.OPAQUE) != 0,
                            new SurfaceControl.Builder(mSurfaceSession)
                                    .setSize(mSurfaceWidth, mSurfaceHeight)
                                    .setFormat(mFormat)
                                    .setFlags(mSurfaceFlags));
                } else if (mSurfaceControl == null) {
                    return;
                }

                boolean realSizeChanged = false;

                mSurfaceLock.lock();
                try {
                    mDrawingStopped = !visible;

                    if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                            + "Cur surface: " + mSurface);

                    SurfaceControl.openTransaction();
                    try {
                        mSurfaceControl.setLayer(mSubLayer);
                        if (mViewVisibility) {
                            mSurfaceControl.show();
                        } else {
                            mSurfaceControl.hide();
                        }

                        // While creating the surface, we will set it's initial
                        // geometry. Outside of that though, we should generally
                        // leave it to the RenderThread.
                        //
                        // There is one more case when the buffer size changes we aren't yet
                        // prepared to sync (as even following the transaction applying
                        // we still need to latch a buffer).
                        // b/28866173
                        if (sizeChanged || creating || !mRtHandlingPositionUpdates) {
                            mSurfaceControl.setPosition(mScreenRect.left, mScreenRect.top);
                            mSurfaceControl.setMatrix(mScreenRect.width() / (float) mSurfaceWidth,
                                    0.0f, 0.0f,
                                    mScreenRect.height() / (float) mSurfaceHeight);
                        }
                        if (sizeChanged) {
                            mSurfaceControl.setSize(mSurfaceWidth, mSurfaceHeight);
                        }
                    } finally {
                        SurfaceControl.closeTransaction();
                    }

                    if (sizeChanged || creating) {
                        redrawNeeded = true;
                    }

                    mSurfaceFrame.left = 0;
                    mSurfaceFrame.top = 0;
                    if (mTranslator == null) {
                        mSurfaceFrame.right = mSurfaceWidth;
                        mSurfaceFrame.bottom = mSurfaceHeight;
                    } else {
                        float appInvertedScale = mTranslator.applicationInvertedScale;
                        mSurfaceFrame.right = (int) (mSurfaceWidth * appInvertedScale + 0.5f);
                        mSurfaceFrame.bottom = (int) (mSurfaceHeight * appInvertedScale + 0.5f);
                    }

                    final int surfaceWidth = mSurfaceFrame.right;
                    final int surfaceHeight = mSurfaceFrame.bottom;
                    realSizeChanged = mLastSurfaceWidth != surfaceWidth
                            || mLastSurfaceHeight != surfaceHeight;
                    mLastSurfaceWidth = surfaceWidth;
                    mLastSurfaceHeight = surfaceHeight;
                } finally {
                    mSurfaceLock.unlock();
                }

                try {
                    redrawNeeded |= visible && !mDrawFinished;

                    SurfaceHolder.Callback callbacks[] = null;

                    final boolean surfaceChanged = creating;
                    if (mSurfaceCreated && (surfaceChanged || (!visible && visibleChanged))) {
                        mSurfaceCreated = false;
                        if (mSurface.isValid()) {
                            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                                    + "visibleChanged -- surfaceDestroyed");
                            callbacks = getSurfaceCallbacks();
                            for (SurfaceHolder.Callback c : callbacks) {
                                c.surfaceDestroyed(mSurfaceHolder);
                            }
                            // Since Android N the same surface may be reused and given to us
                            // again by the system server at a later point. However
                            // as we didn't do this in previous releases, clients weren't
                            // necessarily required to clean up properly in
                            // surfaceDestroyed. This leads to problems for example when
                            // clients don't destroy their EGL context, and try
                            // and create a new one on the same surface following reuse.
                            // Since there is no valid use of the surface in-between
                            // surfaceDestroyed and surfaceCreated, we force a disconnect,
                            // so the next connect will always work if we end up reusing
                            // the surface.
                            if (mSurface.isValid()) {
                                mSurface.forceScopedDisconnect();
                            }
                        }
                    }

                    if (creating) {
                        mSurface.copyFrom(mSurfaceControl);
                    }

                    if (sizeChanged && getContext().getApplicationInfo().targetSdkVersion
                            < Build.VERSION_CODES.O) {
                        // Some legacy applications use the underlying native {@link Surface} object
                        // as a key to whether anything has changed. In these cases, updates to the
                        // existing {@link Surface} will be ignored when the size changes.
                        // Therefore, we must explicitly recreate the {@link Surface} in these
                        // cases.
                        mSurface.createFrom(mSurfaceControl);
                    }

                    if (visible && mSurface.isValid()) {
                        if (!mSurfaceCreated && (surfaceChanged || visibleChanged)) {
                            mSurfaceCreated = true;
                            mIsCreating = true;
                            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                                    + "visibleChanged -- surfaceCreated");
                            if (callbacks == null) {
                                callbacks = getSurfaceCallbacks();
                            }
                            for (SurfaceHolder.Callback c : callbacks) {
                                c.surfaceCreated(mSurfaceHolder);
                            }
                        }
                        if (creating || formatChanged || sizeChanged
                                || visibleChanged || realSizeChanged) {
                            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                                    + "surfaceChanged -- format=" + mFormat
                                    + " w=" + myWidth + " h=" + myHeight);
                            if (callbacks == null) {
                                callbacks = getSurfaceCallbacks();
                            }
                            for (SurfaceHolder.Callback c : callbacks) {
                                c.surfaceChanged(mSurfaceHolder, mFormat, myWidth, myHeight);
                            }
                        }
                        if (redrawNeeded) {
                            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                                    + "surfaceRedrawNeeded");
                            if (callbacks == null) {
                                callbacks = getSurfaceCallbacks();
                            }

                            mPendingReportDraws++;
                            viewRoot.drawPending();
                            SurfaceCallbackHelper sch =
                                    new SurfaceCallbackHelper(this::onDrawFinished);
                            sch.dispatchSurfaceRedrawNeededAsync(mSurfaceHolder, callbacks);
                        }
                    }
                } finally {
                    mIsCreating = false;
                    if (mSurfaceControl != null && !mSurfaceCreated) {
                        mSurface.release();

                        mSurfaceControl.destroy();
                        mSurfaceControl = null;
                    }
                }
            } catch (Exception ex) {
                Log.e(TAG, "Exception configuring surface", ex);
            }
            if (DEBUG) Log.v(
                TAG, "Layout: x=" + mScreenRect.left + " y=" + mScreenRect.top
                + " w=" + mScreenRect.width() + " h=" + mScreenRect.height()
                + ", frame=" + mSurfaceFrame);
        } else {
            // Calculate the window position in case RT loses the window
            // and we need to fallback to a UI-thread driven position update
            getLocationInSurface(mLocation);
            final boolean positionChanged = mWindowSpaceLeft != mLocation[0]
                    || mWindowSpaceTop != mLocation[1];
            final boolean layoutSizeChanged = getWidth() != mScreenRect.width()
                    || getHeight() != mScreenRect.height();
            if (positionChanged || layoutSizeChanged) { // Only the position has changed
                mWindowSpaceLeft = mLocation[0];
                mWindowSpaceTop = mLocation[1];
                // For our size changed check, we keep mScreenRect.width() and mScreenRect.height()
                // in view local space.
                mLocation[0] = getWidth();
                mLocation[1] = getHeight();

                mScreenRect.set(mWindowSpaceLeft, mWindowSpaceTop,
                        mWindowSpaceLeft + mLocation[0], mWindowSpaceTop + mLocation[1]);

                if (mTranslator != null) {
                    mTranslator.translateRectInAppWindowToScreen(mScreenRect);
                }

                if (mSurfaceControl == null) {
                    return;
                }

                if (!isHardwareAccelerated() || !mRtHandlingPositionUpdates) {
                    try {
                        if (DEBUG) Log.d(TAG, String.format("%d updateSurfacePosition UI, " +
                                "postion = [%d, %d, %d, %d]", System.identityHashCode(this),
                                mScreenRect.left, mScreenRect.top,
                                mScreenRect.right, mScreenRect.bottom));
                        setParentSpaceRectangle(mScreenRect, -1);
                    } catch (Exception ex) {
                        Log.e(TAG, "Exception configuring surface", ex);
                    }
                }
            }
        }
    }

    private void onDrawFinished() {
        if (DEBUG) {
            Log.i(TAG, System.identityHashCode(this) + " "
                    + "finishedDrawing");
        }

        if (mDeferredDestroySurfaceControl != null) {
            mDeferredDestroySurfaceControl.destroy();
            mDeferredDestroySurfaceControl = null;
        }

        runOnUiThread(() -> {
            performDrawFinished();
        });
    }

    
A place to over-ride for applying child-surface transactions.
These can be synchronized with the viewroot surface using deferTransaction.
Called from RenderWorker while UI thread is paused.

@hide
/**
     * A place to over-ride for applying child-surface transactions.
     * These can be synchronized with the viewroot surface using deferTransaction.
     *
     * Called from RenderWorker while UI thread is paused.
     * @hide
     */
    protected void applyChildSurfaceTransaction_renderWorker(SurfaceControl.Transaction t,
            Surface viewRootSurface, long nextViewRootFrameNumber) {
    }

    private void applySurfaceTransforms(SurfaceControl surface, Rect position, long frameNumber) {
        if (frameNumber > 0) {
            final ViewRootImpl viewRoot = getViewRootImpl();

            mRtTransaction.deferTransactionUntilSurface(surface, viewRoot.mSurface,
                    frameNumber);
        }

        mRtTransaction.setPosition(surface, position.left, position.top);
        mRtTransaction.setMatrix(surface,
                position.width() / (float) mSurfaceWidth,
                0.0f, 0.0f,
                position.height() / (float) mSurfaceHeight);
    }

    private void setParentSpaceRectangle(Rect position, long frameNumber) {
        final ViewRootImpl viewRoot = getViewRootImpl();

        applySurfaceTransforms(mSurfaceControl, position, frameNumber);
        applySurfaceTransforms(mSurfaceControl.mBackgroundControl, position, frameNumber);

        applyChildSurfaceTransaction_renderWorker(mRtTransaction, viewRoot.mSurface,
                frameNumber);

        mRtTransaction.apply();
    }

    private Rect mRTLastReportedPosition = new Rect();

    
Called by native by a Rendering Worker thread to update the window position

@hide
/**
     * Called by native by a Rendering Worker thread to update the window position
     * @hide
     */
    public final void updateSurfacePosition_renderWorker(long frameNumber,
            int left, int top, int right, int bottom) {
        if (mSurfaceControl == null) {
            return;
        }

        // TODO: This is teensy bit racey in that a brand new SurfaceView moving on
        // its 2nd frame if RenderThread is running slowly could potentially see
        // this as false, enter the branch, get pre-empted, then this comes along
        // and reports a new position, then the UI thread resumes and reports
        // its position. This could therefore be de-sync'd in that interval, but
        // the synchronization would violate the rule that RT must never block
        // on the UI thread which would open up potential deadlocks. The risk of
        // a single-frame desync is therefore preferable for now.
        mRtHandlingPositionUpdates = true;
        if (mRTLastReportedPosition.left == left
                && mRTLastReportedPosition.top == top
                && mRTLastReportedPosition.right == right
                && mRTLastReportedPosition.bottom == bottom) {
            return;
        }
        try {
            if (DEBUG) {
                Log.d(TAG, String.format("%d updateSurfacePosition RenderWorker, frameNr = %d, " +
                        "postion = [%d, %d, %d, %d]", System.identityHashCode(this),
                        frameNumber, left, top, right, bottom));
            }
            mRTLastReportedPosition.set(left, top, right, bottom);
            setParentSpaceRectangle(mRTLastReportedPosition, frameNumber);
            // Now overwrite mRTLastReportedPosition with our values
        } catch (Exception ex) {
            Log.e(TAG, "Exception from repositionChild", ex);
        }
    }

    
Called by native on RenderThread to notify that the view is no longer in the
draw tree. UI thread is blocked at this point.

@hide
/**
     * Called by native on RenderThread to notify that the view is no longer in the
     * draw tree. UI thread is blocked at this point.
     * @hide
     */
    public final void surfacePositionLost_uiRtSync(long frameNumber) {
        if (DEBUG) {
            Log.d(TAG, String.format("%d windowPositionLost, frameNr = %d",
                    System.identityHashCode(this), frameNumber));
        }
        mRTLastReportedPosition.setEmpty();

        if (mSurfaceControl == null) {
            return;
        }
        if (mRtHandlingPositionUpdates) {
            mRtHandlingPositionUpdates = false;
            // This callback will happen while the UI thread is blocked, so we can
            // safely access other member variables at this time.
            // So do what the UI thread would have done if RT wasn't handling position
            // updates.
            if (!mScreenRect.isEmpty() && !mScreenRect.equals(mRTLastReportedPosition)) {
                try {
                    if (DEBUG) Log.d(TAG, String.format("%d updateSurfacePosition, " +
                            "postion = [%d, %d, %d, %d]", System.identityHashCode(this),
                            mScreenRect.left, mScreenRect.top,
                            mScreenRect.right, mScreenRect.bottom));
                    setParentSpaceRectangle(mScreenRect, frameNumber);
                } catch (Exception ex) {
                    Log.e(TAG, "Exception configuring surface", ex);
                }
            }
        }
    }

    private SurfaceHolder.Callback[] getSurfaceCallbacks() {
        SurfaceHolder.Callback callbacks[];
        synchronized (mCallbacks) {
            callbacks = new SurfaceHolder.Callback[mCallbacks.size()];
            mCallbacks.toArray(callbacks);
        }
        return callbacks;
    }

    private void runOnUiThread(Runnable runnable) {
        Handler handler = getHandler();
        if (handler != null && handler.getLooper() != Looper.myLooper()) {
            handler.post(runnable);
        } else {
            runnable.run();
        }
    }

    
Check to see if the surface has fixed size dimensions or if the surface's
dimensions are dimensions are dependent on its current layout.

Returns:true if the surface has dimensions that are fixed in size
@hide
/**
     * Check to see if the surface has fixed size dimensions or if the surface's
     * dimensions are dimensions are dependent on its current layout.
     *
     * @return true if the surface has dimensions that are fixed in size
     * @hide
     */
    public boolean isFixedSize() {
        return (mRequestedWidth != -1 || mRequestedHeight != -1);
    }

    private boolean isAboveParent() {
        return mSubLayer >= 0;
    }

    
Set an opaque background color to use with this SurfaceView when it's being resized and size of the content hasn't updated yet. This color will fill the expanded area when the view becomes larger. 
Params:
  • bgColor – An opaque color to fill the background. Alpha component will be ignored.
@hide
/**
     * Set an opaque background color to use with this {@link SurfaceView} when it's being resized
     * and size of the content hasn't updated yet. This color will fill the expanded area when the
     * view becomes larger.
     * @param bgColor An opaque color to fill the background. Alpha component will be ignored.
     * @hide
     */
    public void setResizeBackgroundColor(int bgColor) {
        mSurfaceControl.setBackgroundColor(bgColor);
    }

    private final SurfaceHolder mSurfaceHolder = new SurfaceHolder() {
        private static final String LOG_TAG = "SurfaceHolder";

        @Override
        public boolean isCreating() {
            return mIsCreating;
        }

        @Override
        public void addCallback(Callback callback) {
            synchronized (mCallbacks) {
                // This is a linear search, but in practice we'll
                // have only a couple callbacks, so it doesn't matter.
                if (mCallbacks.contains(callback) == false) {
                    mCallbacks.add(callback);
                }
            }
        }

        @Override
        public void removeCallback(Callback callback) {
            synchronized (mCallbacks) {
                mCallbacks.remove(callback);
            }
        }

        @Override
        public void setFixedSize(int width, int height) {
            if (mRequestedWidth != width || mRequestedHeight != height) {
                mRequestedWidth = width;
                mRequestedHeight = height;
                requestLayout();
            }
        }

        @Override
        public void setSizeFromLayout() {
            if (mRequestedWidth != -1 || mRequestedHeight != -1) {
                mRequestedWidth = mRequestedHeight = -1;
                requestLayout();
            }
        }

        @Override
        public void setFormat(int format) {
            // for backward compatibility reason, OPAQUE always
            // means 565 for SurfaceView
            if (format == PixelFormat.OPAQUE)
                format = PixelFormat.RGB_565;

            mRequestedFormat = format;
            if (mSurfaceControl != null) {
                updateSurface();
            }
        }

        
Deprecated:setType is now ignored.
/**
         * @deprecated setType is now ignored.
         */
        @Override
        @Deprecated
        public void setType(int type) { }

        @Override
        public void setKeepScreenOn(boolean screenOn) {
            runOnUiThread(() -> SurfaceView.this.setKeepScreenOn(screenOn));
        }

        
Gets a Canvas for drawing into the SurfaceView's Surface After drawing into the provided Canvas, the caller must invoke .unlockCanvasAndPost to post the new contents to the surface. The caller must redraw the entire surface. 
Returns:A canvas for drawing into the surface.
/**
         * Gets a {@link Canvas} for drawing into the SurfaceView's Surface
         *
         * After drawing into the provided {@link Canvas}, the caller must
         * invoke {@link #unlockCanvasAndPost} to post the new contents to the surface.
         *
         * The caller must redraw the entire surface.
         * @return A canvas for drawing into the surface.
         */
        @Override
        public Canvas lockCanvas() {
            return internalLockCanvas(null, false);
        }

        
Gets a Canvas for drawing into the SurfaceView's Surface After drawing into the provided Canvas, the caller must invoke .unlockCanvasAndPost to post the new contents to the surface. 
Params:
  • inOutDirty – A rectangle that represents the dirty region that the caller wants
to redraw.  This function may choose to expand the dirty rectangle if for example
the surface has been resized or if the previous contents of the surface were
not available.  The caller must redraw the entire dirty region as represented
by the contents of the inOutDirty rectangle upon return from this function.
The caller may also pass null instead, in the case where the
entire surface should be redrawn.
Returns:A canvas for drawing into the surface.
/**
         * Gets a {@link Canvas} for drawing into the SurfaceView's Surface
         *
         * After drawing into the provided {@link Canvas}, the caller must
         * invoke {@link #unlockCanvasAndPost} to post the new contents to the surface.
         *
         * @param inOutDirty A rectangle that represents the dirty region that the caller wants
         * to redraw.  This function may choose to expand the dirty rectangle if for example
         * the surface has been resized or if the previous contents of the surface were
         * not available.  The caller must redraw the entire dirty region as represented
         * by the contents of the inOutDirty rectangle upon return from this function.
         * The caller may also pass <code>null</code> instead, in the case where the
         * entire surface should be redrawn.
         * @return A canvas for drawing into the surface.
         */
        @Override
        public Canvas lockCanvas(Rect inOutDirty) {
            return internalLockCanvas(inOutDirty, false);
        }

        @Override
        public Canvas lockHardwareCanvas() {
            return internalLockCanvas(null, true);
        }

        private Canvas internalLockCanvas(Rect dirty, boolean hardware) {
            mSurfaceLock.lock();

            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " " + "Locking canvas... stopped="
                    + mDrawingStopped + ", surfaceControl=" + mSurfaceControl);

            Canvas c = null;
            if (!mDrawingStopped && mSurfaceControl != null) {
                try {
                    if (hardware) {
                        c = mSurface.lockHardwareCanvas();
                    } else {
                        c = mSurface.lockCanvas(dirty);
                    }
                } catch (Exception e) {
                    Log.e(LOG_TAG, "Exception locking surface", e);
                }
            }

            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " " + "Returned canvas: " + c);
            if (c != null) {
                mLastLockTime = SystemClock.uptimeMillis();
                return c;
            }

            // If the Surface is not ready to be drawn, then return null,
            // but throttle calls to this function so it isn't called more
            // than every 100ms.
            long now = SystemClock.uptimeMillis();
            long nextTime = mLastLockTime + 100;
            if (nextTime > now) {
                try {
                    Thread.sleep(nextTime-now);
                } catch (InterruptedException e) {
                }
                now = SystemClock.uptimeMillis();
            }
            mLastLockTime = now;
            mSurfaceLock.unlock();

            return null;
        }

        
Posts the new contents of the Canvas to the surface and releases the Canvas. 
Params:
  • canvas – The canvas previously obtained from .lockCanvas.
/**
         * Posts the new contents of the {@link Canvas} to the surface and
         * releases the {@link Canvas}.
         *
         * @param canvas The canvas previously obtained from {@link #lockCanvas}.
         */
        @Override
        public void unlockCanvasAndPost(Canvas canvas) {
            mSurface.unlockCanvasAndPost(canvas);
            mSurfaceLock.unlock();
        }

        @Override
        public Surface getSurface() {
            return mSurface;
        }

        @Override
        public Rect getSurfaceFrame() {
            return mSurfaceFrame;
        }
    };

    class SurfaceControlWithBackground extends SurfaceControl {
        SurfaceControl mBackgroundControl;
        private boolean mOpaque = true;
        public boolean mVisible = false;

        public SurfaceControlWithBackground(String name, boolean opaque, SurfaceControl.Builder b)
                       throws Exception {
            super(b.setName(name).build());

            mBackgroundControl = b.setName("Background for -" + name)
                    .setFormat(OPAQUE)
                    .setColorLayer(true)
                    .build();
            mOpaque = opaque;
        }

        @Override
        public void setAlpha(float alpha) {
            super.setAlpha(alpha);
            mBackgroundControl.setAlpha(alpha);
        }

        @Override
        public void setLayer(int zorder) {
            super.setLayer(zorder);
            // -3 is below all other child layers as SurfaceView never goes below -2
            mBackgroundControl.setLayer(-3);
        }

        @Override
        public void setPosition(float x, float y) {
            super.setPosition(x, y);
            mBackgroundControl.setPosition(x, y);
        }

        @Override
        public void setSize(int w, int h) {
            super.setSize(w, h);
            mBackgroundControl.setSize(w, h);
        }

        @Override
        public void setWindowCrop(Rect crop) {
            super.setWindowCrop(crop);
            mBackgroundControl.setWindowCrop(crop);
        }

        @Override
        public void setFinalCrop(Rect crop) {
            super.setFinalCrop(crop);
            mBackgroundControl.setFinalCrop(crop);
        }

        @Override
        public void setLayerStack(int layerStack) {
            super.setLayerStack(layerStack);
            mBackgroundControl.setLayerStack(layerStack);
        }

        @Override
        public void setOpaque(boolean isOpaque) {
            super.setOpaque(isOpaque);
            mOpaque = isOpaque;
            updateBackgroundVisibility();
        }

        @Override
        public void setSecure(boolean isSecure) {
            super.setSecure(isSecure);
        }

        @Override
        public void setMatrix(float dsdx, float dtdx, float dsdy, float dtdy) {
            super.setMatrix(dsdx, dtdx, dsdy, dtdy);
            mBackgroundControl.setMatrix(dsdx, dtdx, dsdy, dtdy);
        }

        @Override
        public void hide() {
            super.hide();
            mVisible = false;
            updateBackgroundVisibility();
        }

        @Override
        public void show() {
            super.show();
            mVisible = true;
            updateBackgroundVisibility();
        }

        @Override
        public void destroy() {
            super.destroy();
            mBackgroundControl.destroy();
         }

        @Override
        public void release() {
            super.release();
            mBackgroundControl.release();
        }

        @Override
        public void setTransparentRegionHint(Region region) {
            super.setTransparentRegionHint(region);
            mBackgroundControl.setTransparentRegionHint(region);
        }

        @Override
        public void deferTransactionUntil(IBinder handle, long frame) {
            super.deferTransactionUntil(handle, frame);
            mBackgroundControl.deferTransactionUntil(handle, frame);
        }

        @Override
        public void deferTransactionUntil(Surface barrier, long frame) {
            super.deferTransactionUntil(barrier, frame);
            mBackgroundControl.deferTransactionUntil(barrier, frame);
        }

        
Set the color to fill the background with. 
/** Set the color to fill the background with. */
        private void setBackgroundColor(int bgColor) {
            final float[] colorComponents = new float[] { Color.red(bgColor) / 255.f,
                    Color.green(bgColor) / 255.f, Color.blue(bgColor) / 255.f };

            SurfaceControl.openTransaction();
            try {
                mBackgroundControl.setColor(colorComponents);
            } finally {
                SurfaceControl.closeTransaction();
            }
        }

        void updateBackgroundVisibility() {
            if (mOpaque && mVisible) {
                mBackgroundControl.show();
            } else {
                mBackgroundControl.hide();
            }
        }
    }
}