shubendrak shubendrak - 17 days ago 16
Android Question

Android - Get byte[] from Surface / virtualDisplay

I am trying to screen cast my android device screen to a web browser using

projection API
and
Webrtc
.

Projection API
renders its output to a
Surface
and returns a virtualDisplay. I have done till this. I saw the webrtc library for android. they have made it to receive input only from device camera. I am trying to read and modify webrtc code to stream whatever is shown to the surface.

My question is How can i receive byte[] data from a
surface
regularly like the
Camera.PreviewCallback
function. What other available options i have?

Answer

Here is how i solved my problem. I used ImageReader class like

imageReader = ImageReader.newInstance(displayWidth, displayHeight, PixelFormat.RGBA_8888, 2);
mediaProjection.createVirtualDisplay("screencapture",
                    displayWidth, displayHeight, density,
                    flags, imageReader.getSurface(), null, handler);
imageReader.setOnImageAvailableListener(new ImageAvailableListener(), null);


private class ImageAvailableListener implements ImageReader.OnImageAvailableListener {
    @Override
    public void onImageAvailable(ImageReader reader) {
        Image image = null;
        Bitmap bitmap = null;

        ByteArrayOutputStream stream = null;

        try {
            image = imageReader.acquireLatestImage();
            if (image != null) {
                Image.Plane[] planes = image.getPlanes();
                ByteBuffer buffer = planes[0].getBuffer();
                int pixelStride = planes[0].getPixelStride();
                int rowStride = planes[0].getRowStride();
                int rowPadding = rowStride - pixelStride * displayWidth;

                // create bitmap
                bitmap = Bitmap.createBitmap(displayWidth + rowPadding / pixelStride,
                        displayHeight, Bitmap.Config.ARGB_8888);
                bitmap.copyPixelsFromBuffer(buffer);
                    stream = new ByteArrayOutputStream();
                    bitmap.compress(Bitmap.CompressFormat.JPEG, 50, stream);
                    StringBuilder sb = new StringBuilder();
                    sb.append("data:image/png;base64,");
                    sb.append(StringUtils.newStringUtf8(Base64.encode(stream.toByteArray(), Base64.DEFAULT)));
                WebrtcClient.sendProjection(sb.toString());
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

I am converting byte[] to Base64 string and sending to through webrtc datachannel.

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