安卓表面 View : Show Video after Images

Question

我想在同一个 SurfaceView 中播放几张图片后播放一段视频。如果我在视频后显示图像，一切正常。但是如果我想在图像之后播放视频，SurfaceView 将保持空白(黑色)。谁能帮忙？好像是清除或重置SurfaceView的问题!

SurfaceView的代码(自定义SurfaceView!!!):

public class MySurfaceView extends SurfaceView implements  SurfaceHolder.Callback, MediaPlayer.OnCompletionListener {

    private Bitmap image;
    private MediaPlayer mediaPlayer;
    private List<MySurfaceListener> objectsToCall = new ArrayList<>();

    public MySurfaceView(Context context) {
        super(context);
        getHolder().addCallback(this);
    }

    public void addOnPlayingFinishedListener(MySurfaceListener listener) {
        objectsToCall.add(listener);
    }

    public void notifyAllOnPlayingFinishedListener() {
        for(MySurfaceListener l : objectsToCall) {
            l.onMediaPlayFinished();
        }
    }

    public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        // Helper method to scale down the image files
    }

    public static Bitmap decodeSampledBitmapFromFile(String path, int reqWidth, int reqHeight) {

        // Another helper method for the image files
    }

    public void drawImage(String path, final int durationMs) {
        this.image = decodeSampledBitmapFromFile(path, 1920, 1080);
        Canvas canvas = null;
        try {
            canvas = getHolder().lockCanvas(null);
            synchronized (getHolder()) {
                onDraw(canvas);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (canvas != null) {
                getHolder().unlockCanvasAndPost(canvas);
            }
            image.recycle();
            image = null;
        }

        Thread showPictureTimer = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(durationMs);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
        showPictureTimer.start();
        try {
            showPictureTimer.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        notifyAllOnPlayingFinishedListener();
    }

    public void playVideo(String path) {
        try {
            mediaPlayer = new MediaPlayer();
            mediaPlayer.setOnCompletionListener(this);
            mediaPlayer.setDisplay(getHolder());
            mediaPlayer.setDataSource(path);
            mediaPlayer.prepare();
            mediaPlayer.start();
        } catch (IllegalArgumentException e) {
            Log.d("MyMediaPlayerControl", e.getMessage());
        } catch (IllegalStateException e) {
            Log.d("MyMediaPlayerControl", e.getMessage());
        } catch (IOException e) {
            Log.d("MyMediaPlayerControl", e.getMessage());
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.BLACK);
        canvas.drawBitmap(this.image, 0, 0, new Paint());
    }

    public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
        Log.e("myApp", "surfaceChanged");
    }

    public void surfaceCreated(SurfaceHolder arg0) {
        Log.e("myApp", "surfaceCreated");
    }

    public void surfaceDestroyed(SurfaceHolder arg0) {
        Log.e("myApp", "surfaceDestroyed");
    }

    @Override
    public void onCompletion(MediaPlayer mp) {
        if (mediaPlayer != null) {
            mediaPlayer.stop();
            mediaPlayer.release();
            mediaPlayer = null;
        }
        notifyAllOnPlayingFinishedListener();
    }
}

以及将文件路径提供给用于播放的表面 View 的线程(应该不是问题所在):

public class MediaControlThread extends Thread implements MySurfaceListener {
    public static List<String> mediaList = new ArrayList<String>();
    MyMediaActivity activity;
    private MySurfaceView surfaceView;
    private int currentVideo = 0;

    public MediaControlThread(MyMediaActivity activity) {
        this.activity = activity;
        this.surfaceView = activity.getSurfaceView();
        this.surfaceView.addOnPlayingFinishedListener(this);
    }

    @Override
    public void run() {
        try {
            while(mediaList.size() == 0) {
               Thread.sleep(1000);
            }
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        playMedia(mediaList.get(currentVideo));
    }

    private void playMedia(String mediaPath) {
        if(checkFileForImage(mediaPath)) {
            surfaceView.drawImage(mediaPath, 2000);
        } else {
            surfaceView.playVideo(mediaPath);
        }
    }

    private boolean checkFileForImage(String fileName) {
        String file = fileName.toLowerCase();
        return file.endsWith(".jpg") ||
                file.endsWith(".img") ||
                file.endsWith(".bmp") ||
                file.endsWith(".jpeg") ||
                file.endsWith(".ico") ||
                file.endsWith(".tif");
    }

    @Override
    public void onMediaPlayFinished() {
        surfaceView.invalidate();
        surfaceView.destroyDrawingCache();
        currentVideo++;
        if (currentVideo > mediaList.size() - 1) {
            currentVideo = 0;
        }
        playMedia(mediaList.get(currentVideo));
    }
}

Answer 1

不幸的是，这是预期的行为。由于 Android 中的一个怪癖，一旦您使用 Canvas 在 Surface 上绘图，您将无法执行任何其他操作。

你有三个选择:

1. 使用 OpenGL ES 而不是 Canvas 绘制图像。分离 GLES 后，您可以返回显示视频。
2. 将图片呈现为单帧视频。这对于让屏幕空白等琐碎的事情非常有效，但对于动态内容来说是一个糟糕的选择。
3. 使用 FrameLayout 覆盖 ImageView 或自定义 View 。当你想显示图像时显示 View ，否则隐藏它。只要 Surface 处于默认的 Z 深度，ImageView 就会出现在它的前面并遮住它。