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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
const Ci = Components.interfaces;
const Cc = Components.classes;
const Cu = Components.utils;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
const XHTML_NS = "http://www.w3.org/1999/xhtml";
const MAXIMUM_PIXELS = Math.pow(144, 2);
function ColorAnalyzer() {
// a queue of callbacks for each job we give to the worker
this.callbacks = [];
this.hiddenWindowDoc = Cc["@mozilla.org/appshell/appShellService;1"].
getService(Ci.nsIAppShellService).
hiddenDOMWindow.document;
this.worker = new ChromeWorker("resource://gre/modules/ColorAnalyzer_worker.js");
this.worker.onmessage = this.onWorkerMessage.bind(this);
this.worker.onerror = this.onWorkerError.bind(this);
}
ColorAnalyzer.prototype = {
findRepresentativeColor: function ColorAnalyzer_frc(imageURI, callback) {
function cleanup() {
image.removeEventListener("load", loadListener);
image.removeEventListener("error", errorListener);
}
let image = this.hiddenWindowDoc.createElementNS(XHTML_NS, "img");
let loadListener = this.onImageLoad.bind(this, image, callback, cleanup);
let errorListener = this.onImageError.bind(this, image, callback, cleanup);
image.addEventListener("load", loadListener);
image.addEventListener("error", errorListener);
image.src = imageURI.spec;
},
onImageLoad: function ColorAnalyzer_onImageLoad(image, callback, cleanup) {
if (image.naturalWidth * image.naturalHeight > MAXIMUM_PIXELS) {
// this will probably take too long to process - fail
callback.onComplete(false);
} else {
let canvas = this.hiddenWindowDoc.createElementNS(XHTML_NS, "canvas");
canvas.width = image.naturalWidth;
canvas.height = image.naturalHeight;
let ctx = canvas.getContext("2d");
ctx.drawImage(image, 0, 0);
this.startJob(ctx.getImageData(0, 0, canvas.width, canvas.height),
callback);
}
cleanup();
},
onImageError: function ColorAnalyzer_onImageError(image, callback, cleanup) {
Cu.reportError("ColorAnalyzer: image at " + image.src + " didn't load");
callback.onComplete(false);
cleanup();
},
startJob: function ColorAnalyzer_startJob(imageData, callback) {
this.callbacks.push(callback);
this.worker.postMessage({ imageData: imageData, maxColors: 1 });
},
onWorkerMessage: function ColorAnalyzer_onWorkerMessage(event) {
// colors can be empty on failure
if (event.data.colors.length < 1) {
this.callbacks.shift().onComplete(false);
} else {
this.callbacks.shift().onComplete(true, event.data.colors[0]);
}
},
onWorkerError: function ColorAnalyzer_onWorkerError(error) {
// this shouldn't happen, but just in case
error.preventDefault();
Cu.reportError("ColorAnalyzer worker: " + error.message);
this.callbacks.shift().onComplete(false);
},
classID: Components.ID("{d056186c-28a0-494e-aacc-9e433772b143}"),
QueryInterface: XPCOMUtils.generateQI([Ci.mozIColorAnalyzer])
};
this.NSGetFactory = XPCOMUtils.generateNSGetFactory([ColorAnalyzer]);
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