Loading the pixels of a scaled BufferedImage

Question

I'm trying to scale an image to a different width, and height. Then create a pixel array from the pixels of the scaled image. The problem is I get an error.

 java.lang.ClassCastException: sun.awt.image.ToolkitImage cannot be cast to java.awt.image.BufferedImage    

any way I can get the pixels of the new sized image?

here is the code:

protected void scaleImage(int newWidth, int newHeight) {
    try {

        BufferedImage image = (BufferedImage) img.getScaledInstance(newWidth, newHeight, Image.SCALE_SMOOTH);

        width = newWidth;
        height = newHeight;
        scaledWidth = newWidth;
        scaledHeight = newHeight;
        //re init the pixels
        pixels = new int[scaledWidth * scaledHeight];

        ((BufferedImage) image).getRGB(0, 0, scaledWidth, scaledHeight, pixels, 0, scaledWidth);
    } catch (Exception e) {
        e.printStackTrace();
        System.exit(0);
    }
}

Answer 1

The problem you run into is that image.getScaledInstance(...) returns an image, regardless of whether image is an Image or a BufferedImage.

Now, for this reason (and others, mainly performance-related) it is not recommended to use image.getScaledImage(...). See for example The Perils of Image.getScaledInstance() for more information, and some alternative methods of scaling.

Adapted from your code, you can use:

int newWidth, int newHeight; // from method parameters

BufferedImage image = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = image.createGraphics();

try {
    g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g.drawImage(img, 0, 0, newWidth, newHeight, null);
}
finally {
    g.dispose();
}

scaledWidth = newWidth;
scaledHeight = newHeight;

//re init the pixels
pixels = new int[scaledWidth * scaledHeight];
image.getRGB(0, 0, scaledWidth, scaledHeight, pixels, 0, scaledWidth);

See the above link for a step-wise alternative, or use a library like imgscalr for even better results.

If you really want to use getScaledInstace() even after you read the above link, you can use the ImageProducer/ImageConsumer API, to get at the pixels in asynchronous fashion. But the API is old and a little inconvenient to work with.