package org.jbpm.ui.editor;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.PaletteData;
import org.eclipse.swt.graphics.RGB;
/*
* taken from https://bugs.eclipse.org/bugs/show_bug.cgi?id=70949
*/
public class ImageHelper {
public static ImageData downSample(Image image) {
ImageData data = image.getImageData();
if (!data.palette.isDirect && data.depth <= 8)
return data;
// compute a histogram of color frequencies
Map<RGB, ColorCounter> freq = new HashMap<RGB, ColorCounter>();
int width = data.width;
int[] pixels = new int[width];
int[] maskPixels = new int[width];
for (int y = 0, height = data.height; y < height; ++y) {
data.getPixels(0, y, width, pixels, 0);
for (int x = 0; x < width; ++x) {
RGB rgb = data.palette.getRGB(pixels[x]);
ColorCounter counter = freq.get(rgb);
if (counter == null) {
counter = new ColorCounter();
counter.rgb = rgb;
freq.put(rgb, counter);
}
counter.count++;
}
}
// sort colors by most frequently used
ColorCounter[] counters = new ColorCounter[freq.size()];
freq.values().toArray(counters);
Arrays.sort(counters);
// pick the most frequently used 256 (or fewer), and make a palette
ImageData mask = null;
if (data.transparentPixel != -1 || data.maskData != null) {
mask = data.getTransparencyMask();
}
int n = Math.min(256, freq.size());
RGB[] rgbs = new RGB[n + (mask != null ? 1 : 0)];
for (int i = 0; i < n; ++i)
rgbs[i] = counters[i].rgb;
if (mask != null) {
rgbs[rgbs.length - 1] = data.transparentPixel != -1 ? data.palette.getRGB(data.transparentPixel) : new RGB(255, 255, 255);
}
PaletteData palette = new PaletteData(rgbs);
// create a new image using the new palette:
// for each pixel in the old image, look up the best matching
// index in the new palette
ImageData newData = new ImageData(width, data.height, 8, palette);
if (mask != null)
newData.transparentPixel = rgbs.length - 1;
for (int y = 0, height = data.height; y < height; ++y) {
data.getPixels(0, y, width, pixels, 0);
if (mask != null)
mask.getPixels(0, y, width, maskPixels, 0);
for (int x = 0; x < width; ++x) {
if (mask != null && maskPixels[x] == 0) {
pixels[x] = rgbs.length - 1;
} else {
RGB rgb = data.palette.getRGB(pixels[x]);
pixels[x] = closest(rgbs, n, rgb);
}
}
newData.setPixels(0, y, width, pixels, 0);
}
return newData;
}
private static int closest(RGB[] rgbs, int n, RGB rgb) {
int minDist = 256 * 256 * 3;
int minIndex = 0;
for (int i = 0; i < n; ++i) {
RGB rgb2 = rgbs[i];
int da = rgb2.red - rgb.red;
int dg = rgb2.green - rgb.green;
int db = rgb2.blue - rgb.blue;
int dist = da * da + dg * dg + db * db;
if (dist < minDist) {
minDist = dist;
minIndex = i;
}
}
return minIndex;
}
private static class ColorCounter implements Comparable<ColorCounter> {
RGB rgb;
int count;
public int compareTo(ColorCounter o) {
return o.count - count;
}
}
}