Android捕获屏幕到ImageReader的Surface

Question

我目前正在学习一个github项目ScreenCapture的代码,它可以捕获屏幕并在surfaceview中显示图像,这是项目https://github.com/Charlesjean/android-ScreenCapture.我尝试使用以下代码将ImageView表面替换为ImageReader对象的表面:

 mImgReader = ImageReader.newInstance(mWidth, mHeight, ImageFormat.JPEG, 5);
    mSurface = mImgReader.getSurface();// mSurfaceView.getHolder().getSurface();
    mImgReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() {
        @Override
        public void onImageAvailable(ImageReader reader) {
            Log.i(TAG, "in OnImageAvailable");

        }
    }, mHandler);

并创建VirtualDisplay,如下所示:

mVirtualDisplay = mMediaProjection.createVirtualDisplay("ScreenCapture",
              mWidth, mHeight, mScreenDensity,
              DisplayManager.VIRTUAL_DISPLAY_FLAG_OWN_CONTENT_ONLY |
                      DisplayManager.VIRTUAL_DISPLAY_FLAG_PUBLIC,
              mSurface, new VirtualDisplay.Callback() {
                  @Override
                  public void onResumed() {
                      Log.i(TAG, "onResumed");
                      super.onResumed();
                  }

                  @Override
                  public void onPaused() {
                      Log.i(TAG, "onPaused");
                      super.onPaused();
                  }
              }, mHandler);

但这种onImageAvailable方法从未被调用,有没有人对此有任何经验？我无法弄清楚为什么这不起作用.

Answer 1

谢谢Simon,我通过将图像格式更改为PixelFormat.RGBA_8888解决了这个问题,但是当你做我做的事情时,你需要注意其他一些要点,我将它发布在这里,以防将来有人帮助.

数据缓冲区与以下Image.Plane所需的数据缓冲区不完全相同Bitmap:
1.我们用于创建的图像格式ImageReader是PixelFormat.RGBA_8888,因此Image.Plane的缓冲区将首先放置R(ed)通道,然后放置G( reen)频道等.为了将此缓冲区转换为位图,我们需要创建这样的位图,并且位图
bitmap = Bitmap.createBitmap(metrics,width, height, Bitmap.Config.ARGB_8888);
缓冲区需要将Alpha通道放在第一位.
2.我们得到的缓冲区Image.Plane每行有一些填充,我个人认为硬件设备使用它来加速缓冲操作或对齐.所以为了复制这个缓冲区,我们需要删除这些填充.

要了解这两点,请看代码打击:

 public void onImageAvailable(ImageReader reader) {
            Log.i(TAG, "in OnImageAvailable");
            FileOutputStream fos = null;
            Bitmap bitmap = null;
            Image img = null;
            try {
                img = reader.acquireLatestImage();
                if (img != null) {
                    Image.Plane[] planes = img.getPlanes();
                    if (planes[0].getBuffer() == null) {
                        return;
                    }
                    int width = img.getWidth();
                    int height = img.getHeight();
                    int pixelStride = planes[0].getPixelStride();
                    int rowStride = planes[0].getRowStride();
                    int rowPadding = rowStride - pixelStride * width;
                    byte[] newData = new byte[width * height * 4];

                    int offset = 0;
                    bitmap = Bitmap.createBitmap(metrics,width, height, Bitmap.Config.ARGB_8888);
                    ByteBuffer buffer = planes[0].getBuffer();
                    for (int i = 0; i < height; ++i) {
                        for (int j = 0; j < width; ++j) {
                            int pixel = 0;
                            pixel |= (buffer.get(offset) & 0xff) << 16;     // R
                            pixel |= (buffer.get(offset + 1) & 0xff) << 8;  // G
                            pixel |= (buffer.get(offset + 2) & 0xff);       // B
                            pixel |= (buffer.get(offset + 3) & 0xff) << 24; // A
                            bitmap.setPixel(j, i, pixel);
                            offset += pixelStride;
                        }
                        offset += rowPadding;
                    }
                    String name = "/myscreen" + count + ".png";
                    count++;
                    File file = new File(Environment.getExternalStorageDirectory(), name);
                    fos = new FileOutputStream(file);
                    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
                    Log.i(TAG, "image saved in" + Environment.getExternalStorageDirectory() + name);
                    img.close();
                }

            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (null != fos) {
                    try {
                        fos.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (null != bitmap) {
                    bitmap.recycle();
                }
                if (null != img) {
                    img.close();
                }

            }
        }