109 lines
2.7 KiB
JavaScript
109 lines
2.7 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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(function(){
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"use strict";
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let scope;
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if ((typeof exports) !== "undefined"){
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scope = exports;
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}
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else {
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scope = require.register("./colorStatistics", {});
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}
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class Statistic{
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constructor(){
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this.colors = Object.create(null);
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this.numberOfColors = 0;
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this.minBoundary = {count: Number.NEGATIVE_INFINITY};
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this.maxBoundary = {count: Number.POSITIVE_INFINITY, previousColor: this.minBoundary};
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this.minBoundary.nextColor = this.maxBoundary;
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}
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addColor(r, g, b, a){
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const index = String.fromCharCode(r, g, b, a);
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let color = this.colors[index];
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if (!color){
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color = {
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index,
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color: [r, g, b, a],
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count: 0,
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previousColor: this.minBoundary,
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nextColor: this.minBoundary.nextColor
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};
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this.numberOfColors += 1;
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this.minBoundary.nextColor = color;
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color.nextColor.previousColor = color;
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this.colors[index] = color;
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}
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color.count += 1;
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if (color.count > color.nextColor.count){
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// swap colors to remain in right order
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// a_ -> b_ -> c -> d becomes a_ -> c -> b_ -> d
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const a_ = color.previousColor;
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const b_ = color;
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const c = color.nextColor;
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const d = color.nextColor.nextColor;
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a_.nextColor = c;
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c.previousColor = a_;
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c.nextColor = b_;
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b_.previousColor = c;
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b_.nextColor = d;
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d.previousColor = b_;
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}
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}
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getMaxColors(n){
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n = Math.min(n, this.numberOfColors);
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const colors = Object.create(null);
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let current = this.maxBoundary;
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for (;n && current;n -= 1){
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current = current.previousColor;
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colors[current.index] = current;
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}
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return colors;
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}
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}
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scope.compute = function computeColorStatistics(rawData){
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const statistic = new Statistic();
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for (let i = 0, l = rawData.length; i < l; i += 4){
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statistic.addColor(
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rawData[i + 0],
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rawData[i + 1],
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rawData[i + 2],
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rawData[i + 3]
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);
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}
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return statistic;
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};
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scope.hasMoreColors = function hasMoreColors(rawData, threshold, statistic){
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if (statistic){
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return statistic.numberOfColors > threshold;
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}
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else {
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const colors = Object.create(null);
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let count = 0;
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for (let i = 0, l = rawData.length; i < l; i += 4){
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const index = String.fromCharCode(
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rawData[i + 0],
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rawData[i + 1],
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rawData[i + 2],
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rawData[i + 3]
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);
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if (!Object.prototype.hasOwnProperty.call(colors, index)){
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colors[index] = true;
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count += 1;
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if (count > threshold){
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return true;
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}
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}
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}
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return count > threshold;
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}
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};
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}()); |