I found that you can crop rectangles using the built-in Android crop processor (com.android.camera.action.CROP). To crop the rectangles, you need to remove the following parameters from the example that I passed before:
intent.putExtra("outputX", 200); //Set this to define the max size of the output bitmap
intent.putExtra("outputY", 200); //Set this to define the max size of the output bitmap
intent.putExtra("aspectX", 1); //Set this to define the X aspect ratio of the shape
intent.putExtra("aspectY", 1); //Set this to define the Y aspect ratio of the shape
aspectX aspectY . , .