The Tor Browser: browser/metro/base/content/apzc.js@b8a032363ba2 (annotated)

browser/metro/base/content/apzc.js@b8a032363ba2 (annotated)

browser/metro/base/content/apzc.js

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 // -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
 /* 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/. */
 let Cc = Components.classes;
 let Ci = Components.interfaces;
 let Cu = Components.utils;
 let Cr = Components.results;
 /**
  * Misc. front end utilities for apzc management.
  * the pref: layers.async-pan-zoom.enabled is true.
  */
 var APZCObserver = {
   _debugEvents: false,
   _enabled: false,
   get enabled() {
     return this._enabled;
   },
   init: function() {
     this._enabled = Services.prefs.getBoolPref(kAsyncPanZoomEnabled);
     if (!this._enabled) {
       return;
     }
     let os = Services.obs;
     os.addObserver(this, "apzc-transform-begin", false);
     Elements.tabList.addEventListener("TabSelect", this, true);
     Elements.browsers.addEventListener("pageshow", this, true);
     messageManager.addMessageListener("Content:ZoomToRect", this);
   },
   shutdown: function shutdown() {
     if (!this._enabled) {
       return;
     }
     let os = Services.obs;
     os.removeObserver(this, "apzc-transform-begin");
     Elements.tabList.removeEventListener("TabSelect", this, true);
     Elements.browsers.removeEventListener("pageshow", this, true);
     messageManager.removeMessageListener("Content:ZoomToRect", this);
   },
   handleEvent: function APZC_handleEvent(aEvent) {
     switch (aEvent.type) {
       case 'TabSelect':
         this._resetDisplayPort();
         break;
       case 'pageshow':
         if (aEvent.target != Browser.selectedBrowser.contentDocument) {
           break;
         }
         this._resetDisplayPort();
         break;
     }
   },
   observe: function ao_observe(aSubject, aTopic, aData) {
     if (aTopic == "apzc-transform-begin") {
       // When we're panning, hide the main scrollbars by setting imprecise
       // input (which sets a property on the browser which hides the scrollbar
       // via CSS).  This reduces jittering from left to right. We may be able
       // to get rid of this once we implement axis locking in /gfx APZC.
       if (InputSourceHelper.isPrecise) {
         InputSourceHelper._imprecise();
       }
     }
   },
   receiveMessage: function(aMessage) {
     let json = aMessage.json;
     let browser = aMessage.target;
     switch (aMessage.name) {
       case "Content:ZoomToRect": {
         let { presShellId, viewId } = json;
         let rect = Rect.fromRect(json.rect);
         if (this.isRectZoomedIn(rect, browser.contentViewportBounds)) {
           // If we're already zoomed in, zoom out instead.
           rect = new Rect(0,0,0,0);
         }
         let data = [rect.x, rect.y, rect.width, rect.height, presShellId, viewId].join(",");
         Services.obs.notifyObservers(null, "apzc-zoom-to-rect", data);
       }
     }
   },
   /**
    * Check to see if the area of the rect visible in the viewport is
    * approximately the max area of the rect we can show.
    * Based on code from BrowserElementPanning.js
    */
   isRectZoomedIn: function (aRect, aViewport) {
     let overlap = aViewport.intersect(aRect);
     let overlapArea = overlap.width * overlap.height;
     let availHeight = Math.min(aRect.width * aViewport.height / aViewport.width, aRect.height);
     let showing = overlapArea / (aRect.width * availHeight);
     let ratioW = (aRect.width / aViewport.width);
     let ratioH = (aRect.height / aViewport.height);
     return (showing > 0.9 && (ratioW > 0.9 || ratioH > 0.9));
   },
   _resetDisplayPort: function () {
     // Start off with something reasonable. The apzc will handle these
     // calculations once scrolling starts.
     let doc = Browser.selectedBrowser.contentDocument.documentElement;
     // While running tests, sometimes this can be null. If we don't have a
     // root document, there's no point in setting a scrollable display port.
     if (!doc) {
       return;
     }
     let win = Browser.selectedBrowser.contentWindow;
     let factor = 0.2;
     let portX = 0;
     let portY = 0;
     let portWidth = ContentAreaObserver.width;
     let portHeight = ContentAreaObserver.height;
     if (portWidth < doc.scrollWidth) {
       portWidth += ContentAreaObserver.width * factor;
       if (portWidth > doc.scrollWidth) {
         portWidth = doc.scrollWidth;
       }
     }
     if (portHeight < doc.scrollHeight) {
       portHeight += ContentAreaObserver.height * factor;
       if (portHeight > doc.scrollHeight) {
         portHeight = doc.scrollHeight;
       }
     }
     if (win.scrollX > 0) {
       portX -= ContentAreaObserver.width * factor;
     }
     if (win.scrollY > 0) {
       portY -= ContentAreaObserver.height * factor;
     }
     let cwu = Browser.selectedBrowser.contentWindow
                       .QueryInterface(Ci.nsIInterfaceRequestor)
                       .getInterface(Ci.nsIDOMWindowUtils);
     cwu.setDisplayPortForElement(portX, portY,
                                  portWidth, portHeight,
                                  Browser.selectedBrowser.contentDocument.documentElement,
 );
   }
 };