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konva/experimental/pixelate.js

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Pixelate = (function () {
var Pixelate = function (src, dst, opt) {
var xBinSize = opt.width || 8,
yBinSize = opt.height || 8;
var xSize = src.width,
ySize = src.height,
srcPixels = src.data,
dstPixels = dst.data,
x, y, i;
var pixelsPerBin = xBinSize * yBinSize,
reds = [],
greens = [],
blues = [],
alphas = [],
red, green, blue, alpha,
nBinsX = Math.floor(xSize / opt.width),
nBinsY = Math.floor(ySize / opt.height),
xBinStart, xBinEnd, yBinStart, yBinEnd,
xBin, yBin;
for (xBin = 0; xBin < nBinsX; xBin += 1) {
// Add a new 'row'
reds.push([]);
greens.push([]);
blues.push([]);
alphas.push([]);
for (yBin = 0; yBin < nBinsY; yBin += 1) {
// Initialize all bins to 0
red = 0;
green = 0;
blue = 0;
alpha = 0;
// Determine which pixels are included in this bin
xBinStart = xBin * xBinSize;
xBinEnd = xBinStart + xBinSize;
yBinStart = yBin * yBinSize;
yBinEnd = yBinStart + yBinSize;
// Add all of the pixels to this bin!
for (x = xBinStart; x < xBinEnd; x += 1) {
for (y = yBinStart; y < yBinEnd; y += 1) {
i = (xSize * y + x) * 4;
red += srcPixels[i + 0];
green += srcPixels[i + 1];
blue += srcPixels[i + 2];
alpha += srcPixels[i + 3];
}
}
// Make sure the pixels are between 0-255
reds[xBin].push(red / pixelsPerBin);
greens[xBin].push(green / pixelsPerBin);
blues[xBin].push(blue / pixelsPerBin);
alphas[xBin].push(alpha / pixelsPerBin);
}
}
// For each bin
for (xBin = 0; xBin < nBinsX; xBin += 1) {
for (yBin = 0; yBin < nBinsY; yBin += 1) {
xBinStart = xBin * xBinSize;
xBinEnd = xBinStart + xBinSize;
yBinStart = yBin * yBinSize;
yBinEnd = yBinStart + yBinSize;
// Draw all of the pixels at the bin's average value
for (x = xBinStart; x < xBinEnd; x += 1) {
for (y = yBinStart; y < yBinEnd; y += 1) {
i = (xSize * y + x) * 4;
dstPixels[i + 0] = reds[xBin][yBin];
dstPixels[i + 1] = greens[xBin][yBin];
dstPixels[i + 2] = blues[xBin][yBin];
dstPixels[i + 3] = alphas[xBin][yBin];
}
}
}
}
// I probably don't need to set these to null, but I want to make sure
// the garabage collector removes them
reds = null;
greens = null;
blues = null;
alphas = null;
};
return Pixelate;
})();