1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/browser/components/customizableui/src/ScrollbarSampler.jsm Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,70 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +"use strict";
1.9 +
1.10 +this.EXPORTED_SYMBOLS = ["ScrollbarSampler"];
1.11 +
1.12 +const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
1.13 +
1.14 +Cu.import("resource://gre/modules/Services.jsm");
1.15 +Cu.import("resource://gre/modules/XPCOMUtils.jsm");
1.16 +XPCOMUtils.defineLazyModuleGetter(this, "Promise",
1.17 + "resource://gre/modules/Promise.jsm");
1.18 +
1.19 +let gSystemScrollbarWidth = null;
1.20 +
1.21 +this.ScrollbarSampler = {
1.22 + getSystemScrollbarWidth: function() {
1.23 + let deferred = Promise.defer();
1.24 +
1.25 + if (gSystemScrollbarWidth !== null) {
1.26 + deferred.resolve(gSystemScrollbarWidth);
1.27 + return deferred.promise;
1.28 + }
1.29 +
1.30 + this._sampleSystemScrollbarWidth().then(function(systemScrollbarWidth) {
1.31 + gSystemScrollbarWidth = systemScrollbarWidth;
1.32 + deferred.resolve(gSystemScrollbarWidth);
1.33 + });
1.34 + return deferred.promise;
1.35 + },
1.36 +
1.37 + resetSystemScrollbarWidth: function() {
1.38 + gSystemScrollbarWidth = null;
1.39 + },
1.40 +
1.41 + _sampleSystemScrollbarWidth: function() {
1.42 + let deferred = Promise.defer();
1.43 + let hwin = Services.appShell.hiddenDOMWindow;
1.44 + let hdoc = hwin.document.documentElement;
1.45 + let iframe = hwin.document.createElementNS("http://www.w3.org/1999/xhtml",
1.46 + "html:iframe");
1.47 + iframe.setAttribute("srcdoc", '<body style="overflow-y: scroll"></body>');
1.48 + hdoc.appendChild(iframe);
1.49 +
1.50 + let cwindow = iframe.contentWindow;
1.51 + let utils = cwindow.QueryInterface(Ci.nsIInterfaceRequestor)
1.52 + .getInterface(Ci.nsIDOMWindowUtils);
1.53 +
1.54 + cwindow.addEventListener("load", function onLoad(aEvent) {
1.55 + cwindow.removeEventListener("load", onLoad);
1.56 + let sbWidth = {};
1.57 + try {
1.58 + utils.getScrollbarSize(true, sbWidth, {});
1.59 + } catch(e) {
1.60 + Cu.reportError("Could not sample scrollbar size: " + e + " -- " +
1.61 + e.stack);
1.62 + sbWidth.value = 0;
1.63 + }
1.64 + // Minimum width of 10 so that we have enough padding:
1.65 + sbWidth.value = Math.max(sbWidth.value, 10);
1.66 + deferred.resolve(sbWidth.value);
1.67 + iframe.remove();
1.68 + });
1.69 +
1.70 + return deferred.promise;
1.71 + }
1.72 +};
1.73 +Object.freeze(this.ScrollbarSampler);
