android中将两张图片合并为一张图片

private Bitmap mergeBitmap(Bitmap firstBitmap, Bitmap secondBitmap) {
Bitmap bitmap = Bitmap.createBitmap(firstBitmap.getWidth(), firstBitmap.getHeight(),
firstBitmap.getConfig());
Canvas canvas = new Canvas(bitmap);
canvas.drawBitmap(firstBitmap, new Matrix(), null);
canvas.drawBitmap(secondBitmap, 0, 0, null);
return bitmap;
}