For overlaying two bitmaps:
public static Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {
Bitmap bmOverlay = Bitmap.createBitmap(bmp1.getWidth(), bmp1.getHeight(), bmp1.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp1, new Matrix(), null);
canvas.drawBitmap(bmp2, 0, 0, null);
return bmOverlay;
}
And for scaling one first you should check out createScaledBitmap, e.g:
Bitmap scaledBitmap = Bitmap.createScaledBitmap(src, dstWidth, dstHeight, filter);
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