Change color of non-transparent parts of png in Java

Question

I am trying to automatically change the color for a set of icons. Every icon has a white filled layer and the other part is transparent. Here is an example: (in this case it\'s

Answer 1

Why it doesn't work, I don't know, this will.

This changes all the pixles to blue, maintaining their alpha values...

import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class TestColorReplace {

    public static void main(String[] args) {
        try {
            BufferedImage img = colorImage(ImageIO.read(new File("NWvnS.png")));
            ImageIO.write(img, "png", new File("Test.png"));
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    private static BufferedImage colorImage(BufferedImage image) {
        int width = image.getWidth();
        int height = image.getHeight();
        WritableRaster raster = image.getRaster();

        for (int xx = 0; xx < width; xx++) {
            for (int yy = 0; yy < height; yy++) {
                int[] pixels = raster.getPixel(xx, yy, (int[]) null);
                pixels[0] = 0;
                pixels[1] = 0;
                pixels[2] = 255;
                raster.setPixel(xx, yy, pixels);
            }
        }
        return image;
    }
}

Answer 2

The problem is, that

Color originalColor = new Color(image.getRGB(xx, yy));

discards all the alpha values. Instead you have to use

 Color originalColor = new Color(image.getRGB(xx, yy), true);

to keep alpha values available.

Answer 3

If your bitmap is already set in an ImageView, just do :

imageView.setColorFilter(Color.RED);

to set all non transparent pixels to red.