90 lines
2.2 KiB
JavaScript
90 lines
2.2 KiB
JavaScript
'use strict';
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function dePalette(indata, outdata, width, height, palette) {
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var pxPos = 0;
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// use values from palette
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for (var y = 0; y < height; y++) {
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for (var x = 0; x < width; x++) {
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var color = palette[indata[pxPos]];
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if (!color) {
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throw new Error('index ' + indata[pxPos] + ' not in palette');
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}
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for (var i = 0; i < 4; i++) {
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outdata[pxPos + i] = color[i];
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}
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pxPos += 4;
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}
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}
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}
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function replaceTransparentColor(indata, outdata, width, height, transColor) {
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var pxPos = 0;
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for (var y = 0; y < height; y++) {
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for (var x = 0; x < width; x++) {
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var makeTrans = false;
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if (transColor.length === 1) {
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if (transColor[0] === indata[pxPos]) {
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makeTrans = true;
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}
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}
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else if (transColor[0] === indata[pxPos] && transColor[1] === indata[pxPos + 1] && transColor[2] === indata[pxPos + 2]) {
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makeTrans = true;
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}
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if (makeTrans) {
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for (var i = 0; i < 4; i++) {
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outdata[pxPos + i] = 0;
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}
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}
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pxPos += 4;
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}
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}
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}
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function scaleDepth(indata, outdata, width, height, depth) {
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var maxOutSample = 255;
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var maxInSample = Math.pow(2, depth) - 1;
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var pxPos = 0;
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for (var y = 0; y < height; y++) {
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for (var x = 0; x < width; x++) {
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for (var i = 0; i < 4; i++) {
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outdata[pxPos + i] = Math.floor((indata[pxPos + i] * maxOutSample) / maxInSample + 0.5);
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}
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pxPos += 4;
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}
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}
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}
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module.exports = function(indata, imageData) {
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var depth = imageData.depth;
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var width = imageData.width;
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var height = imageData.height;
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var colorType = imageData.colorType;
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var transColor = imageData.transColor;
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var palette = imageData.palette;
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var outdata = indata; // only different for 16 bits
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if (colorType === 3) { // paletted
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dePalette(indata, outdata, width, height, palette);
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}
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else {
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if (transColor) {
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replaceTransparentColor(indata, outdata, width, height, transColor);
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}
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// if it needs scaling
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if (depth !== 8) {
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// if we need to change the buffer size
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if (depth === 16) {
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outdata = new Buffer(width * height * 4);
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}
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scaleDepth(indata, outdata, width, height, depth);
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}
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}
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return outdata;
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};
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