How to make bitmap transparent?

Question

/**
 * @param bitmap
 *            The source bitmap.
 * @param opacity
 *            a value between 0 (completely transparent) and 255 (completely
 *            op         


        

Answer 1

// Convert transparentColor to be transparent in a Bitmap.
public static Bitmap makeTransparent(Bitmap bit, Color transparentColor) {
    int width =  bit.getWidth();
    int height = bit.getHeight();
    Bitmap myBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    int [] allpixels = new int [ myBitmap.getHeight()*myBitmap.getWidth()];
    bit.getPixels(allpixels, 0, myBitmap.getWidth(), 0, 0, myBitmap.getWidth(),myBitmap.getHeight());
    myBitmap.setPixels(allpixels, 0, width, 0, 0, width, height);

    for(int i =0; i

The above code will take a Bitmap, and return a Bitmap where every pixel which the color is transparentColor is transparent. This works in API as low as level 8, and I have not tested it in any lower.

I typically use something like Color.RED to make my transparent pixels, because I don't use a lot of RED in my assets, but if I do it's a custom red color.