Question

I’m drawing an overlay on an image from the camera and saving the result to a file. To do this, I am passing a callback containing the code below to takePicture(). With larger image sizes, I am getting crashes with an OutOfMemoryError at the first line of the method.

Is there any way I can do this more efficiently? It seems that it’s not possible to make a mutable Bitmap from the byte[], which doubles my memory usage immediately. If it can’t be done this way at high resolutions, how can I produce an overlay on a large captured image without running out of memory?

public void onPictureTaken(byte[] rawPlainImage, Camera camera) {
    Bitmap plainImage = BitmapFactory.decodeByteArray(rawPlainImage, 0, rawPlainImage.length);
    plainImage = plainImage.copy(plainImage.getConfig(), true);
    Canvas combinedImage = new Canvas(plainImage);
    combinedImage.drawBitmap(mOverlay, mOverlayTransformation, null);
    //Write plainImage (now modified) out to a file
    plainImage.recycle();
}

Answer 1

You don’t actually need to decode the image. Instead draw the overlay to the canvas, save the canvas as a bitmap, convert that bitmap to a byte array and then combine the byte array of the canvas and the bitmap and then save that.