The Java Developers Almanac 1.4


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Home > List of Packages > java.awt.image  [21 examples] > Images  [6 examples]

e661. Determining If an Image Has Transparent Pixels

    // This method returns true if the specified image has transparent pixels
    public static boolean hasAlpha(Image image) {
        // If buffered image, the color model is readily available
        if (image instanceof BufferedImage) {
            BufferedImage bimage = (BufferedImage)image;
            return bimage.getColorModel().hasAlpha();
        }
    
        // Use a pixel grabber to retrieve the image's color model;
        // grabbing a single pixel is usually sufficient
         PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
        try {
            pg.grabPixels();
        } catch (InterruptedException e) {
        }
    
        // Get the image's color model
        ColorModel cm = pg.getColorModel();
        return cm.hasAlpha();
    }

 Related Examples
e660. Creating an Image from an Array of Color-Indexed Pixel Values
e662. Getting the Color Model of an Image
e663. Getting the Transparent Pixel and Number of Colors Used in a GIF Image
e664. Getting a Sub-Image of an Image
e665. Filtering the RGB Values in an Image

See also: Buffered Images    Effects    Volatile Images   


© 2002 Addison-Wesley.