How to combine two bitmaps in Android
<p>The first bitmap is set to fill the entire canvas. I then add another bitmap that has been created from an imageview using:</p>

<pre><code>tattoo.buildDrawingCache();
Bitmap bit2 = tattoo.getDrawingCache();
</code></pre>

<p>I then want to add this bitmap over the other keeping it's same scale, rotation, and translation relative to the other bitmap. My issue is that, while the scale and rotation seem fine, the translation shifts to one side or the other. </p>

<pre><code>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, 0,0 , null);

    Matrix matrix = new Matrix();
    matrix.setScale(tattoo.getScaleX() / imageView.getScaleX(), tattoo.getScaleY() / imageView.getScaleY());

    int[] tattooCoords = getRelativeCoords(tattoo);
    int[] imageViewCoords = getRelativeCoords(imageView);
    matrix.setTranslate(tattooCoords[0] - imageViewCoords[0], tattooCoords[1] - imageViewCoords[1]);
    matrix.postRotate(tattoo.getRotation(), tattoo.getX() + tattoo.getWidth() / 2,
            tattoo.getY() + tattoo.getHeight() / 2);
    canvas.drawBitmap(bmp2, matrix, null);

    bmp1.recycle();
    bmp2.recycle();

    return bmOverlay;

}

private static int[] getRelativeCoords(View v){
    View parent = v.getRootView();
    int[] viewLocation = new int[2];
    v.getLocationInWindow(viewLocation);

    int[] rootLocation = new int[2];
    parent.getLocationInWindow(rootLocation);

    int relativeLeft = viewLocation[0] - rootLocation[0];
    int relativeTop  = viewLocation[1] - rootLocation[1];

    return new int[]{relativeLeft, relativeTop};
}
</code></pre>