/**
* Taken from http://today.java.net/pub/a/today/2007/04/03/perils-of-image- getscaledinstance.html
* License: unknown Convenience method that returns a scaled instance of the provided {@code
* BufferedImage}.
*
* @param img the original image to be scaled
* @param targetWidth the desired width of the scaled instance, in pixels
* @param targetHeight the desired height of the scaled instance, in pixels
* @param hint
* @param higherQuality if true, this method will use a multi-step scaling technique that provides
* higher quality than the usual one-step technique (only useful in downscaling cases, where
* {@code targetWidth} or {@code targetHeight} is smaller than the original dimensions, and
* generally only when the {@code BILINEAR} hint is specified)
* @return a scaled version of the original {@code BufferedImage}
*/
public static BufferedImage getScaledInstance(
final Image img,
int width,
int height,
final Interpolation interpolation,
final boolean higherQuality) {
final double faktor =
Math.max((double) img.getWidth(null) / width, (double) img.getHeight(null) / height);
width = Math.max((int) (img.getWidth(null) / faktor), 1);
height = Math.max((int) (img.getHeight(null) / faktor), 1);
if (faktor == 1.0 && img instanceof BufferedImage) {
return (BufferedImage) img;
}
Image ret = img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = Math.max(width, img.getWidth(null));
h = Math.max(height, img.getHeight(null));
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = width;
h = height;
}
do {
if (higherQuality && w > width) {
w /= 2;
if (w < width) {
w = width;
}
}
if (higherQuality && h > height) {
h /= 2;
if (h < height) {
h = height;
}
}
// use 6 as default image type. java versions <16 u17 return type 0
// for loaded pngs
int type = 6;
if (ret instanceof BufferedImage) {
type = ((BufferedImage) ret).getType();
if (type == 0) {
type = 6;
}
}
if (w == 0) {
final int o = 2;
}
final BufferedImage tmp = new BufferedImage(w, h, type);
final Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, interpolation.getHint());
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != width || h != height);
return (BufferedImage) ret;
}
