import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

toolkit/components/places/ColorAnalyzer.js

@@ -0,0 +1,90 @@
+/* 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]);