Android 13媒体投影截图为黑色

Question

我在媒体投影和截图方面遇到错误，但仅限于 android 13，有时它们会显示为黑色，但并非总是如此。我尝试过延迟（最多 5 秒）来看看 Android 系统是否是造成这种情况的原因，但它仍然发生，感谢任何帮助。我确实搜索了该网站，但没有发现有关 android 13 问题的信息。

WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
windowManager.getDefaultDisplay().getRealSize(size);
final int width = size.x, height = size.y;

final ImageReader imageReader = ImageReader.newInstance(width, height, PixelFormat.RGBA_8888, 1);

imageReader.setOnImageAvailableListener(reader -> {
    //-> Stop our media projection just in case it is running
    mediaProjection.stop();

    Image image = reader.acquireLatestImage();
    if (image != null){
      Image.Plane[] planes = image.getPlanes();
      ByteBuffer buffer = planes[0].getBuffer();
      int pixelStride = planes[0].getPixelStride(), rowStride = planes[0].getRowStride(), rowPadding = rowStride - pixelStride * width;
      bitmap = Bitmap.createBitmap(width + rowPadding / pixelStride, height, Bitmap.Config.ARGB_8888);
      bitmap.copyPixelsFromBuffer(buffer); 

      String fileName = "Screenshot_" + System.currentTimeMillis() + ".jpg";
      String destinationPath = this.getExternalFilesDir(null) + "/screenshots/" + fileName;

      File imageFile = new File(destinationPath);
      FileOutputStream outputStream = new FileOutputStream(imageFile);
      int quality = 100;
      bitmap.compress(Bitmap.CompressFormat.JPEG, quality, outputStream);
      outputStream.flush();
      outputStream.close();

      String mediaPath = Environment.DIRECTORY_PICTURES + File.separator + "Screenshots/myapp" + File.separator;

      ContentValues values = new ContentValues();
      values.put(MediaStore.Images.Media.DATE_TAKEN, System.currentTimeMillis());
      values.put(MediaStore.Images.Media.IS_PENDING, 0);
      values.put(MediaStore.Images.Media.RELATIVE_PATH, mediaPath);
      values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg");
      values.put(MediaStore.Images.Media.SIZE, imageFile.length());
      values.put(MediaStore.Images.Media.DISPLAY_NAME, fileName);
      Uri path = this.getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);

      OutputStream imageOutStream = this.getContentResolver().openOutputStream(path);

      bitmap.compress(Bitmap.CompressFormat.JPEG, 100, imageOutStream);
      if (imageOutStream != null) {
         imageOutStream.flush();
         imageOutStream.close();
      }

      if (image != null) { image.close(); }
      mediaProjection.stop();
      if (reader != null){ reader.close(); }
    }
}, null);

Answer 1

根据我的测试和观察，在 Android 13 上使用 ImageReader 进行媒体投影时存在两个问题

首先， 的回调结果setOnImageAvailableListener有时会返回带有空像素的缓冲区。所以我们可以等待下一个图像，直到我们得到一个非空位图

imageReader.setOnImageAvailableListener({ imageReader ->
    val image = imageReader.acquireLatestImage()
    // ... get buffer here
    val bitmap = Bitmap.createBitmap(screenWidth + rowPadding / pixelStride, screenHeight, Bitmap.Config.ARGB_8888)
    bitmap.copyPixelsFromBuffer(buffer)

    // IMPORTANT!
    val isEmptyBitmap = bitmap.isEmptyBitmap()
    if (isEmptyBitmap) {
        // don't stop the listener and let the imageReader continue to run so that we can get next round of image buffer
    } else {
        // save bitmap to file
    }

    }, Handler(Looper.getMainLooper()))

isEmptyBitmap() 只是 Bitmap 的扩展：

fun Bitmap.isEmptyBitmap(): Boolean {
    val emptyBitmap = Bitmap.createBitmap(width, height, config)
    return this.sameAs(emptyBitmap)
}

第二个问题是，OnImageAvailableListener有时甚至不回调！在本例中，我设置了一个超时来等待结果，当超时时，从同一个 MediaProjection 实例重新创建 VirtualDisplay 对象，它就可以工作了。

我正在使用 kotlin 协程，因此代码片段可能如下所示：

retry(10) {
    val imageVirtualDisplay = createVirtualDisplay(...)
    try {
        withTimeout(100) {
            // awaitImageAvailable will suspend here to get the non-empty bitmap
            val bitmap = imageReader.awaitImageAvailable(screenWidth, screenHeight)
            // save bitmap to file
        }
    } finally {
        Timber.d("screenshot imageVirtualDisplay release")
        imageVirtualDisplay?.release()
    }
}

实施awaitImageAvailable：

suspend fun ImageReader.awaitImageAvailable(screenWidth: Int, screenHeight: Int): Bitmap =
suspendCancellableCoroutine { cont ->
    setOnImageAvailableListener({ imageReader ->

        val image = imageReader.acquireLatestImage() ?: throw Error("get screen image result failed")

        val planes = image.planes
        val buffer = planes[0].buffer

        val pixelStride = planes[0].pixelStride
        val rowStride = planes[0].rowStride
        val rowPadding: Int = rowStride - pixelStride * screenWidth
        var bitmap =
            Bitmap.createBitmap(screenWidth + rowPadding / pixelStride, screenHeight, Bitmap.Config.ARGB_8888)
        bitmap.copyPixelsFromBuffer(buffer)
        bitmap = Bitmap.createBitmap(bitmap, 0, 0, screenWidth, screenHeight)
        image.close()

        if (!bitmap.isEmptyBitmap()) {
            Timber.d("image not empty")
            setOnImageAvailableListener(null, null)
            cont.resume(bitmap)
        } else {
            Timber.w("image empty")
        }
    }, Handler(Looper.getMainLooper()))

    cont.invokeOnCancellation { setOnImageAvailableListener(null, null) }
}