michael@0: // -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: let Cc = Components.classes;
michael@0: let Ci = Components.interfaces;
michael@0: let Cu = Components.utils;
michael@0: let Cr = Components.results;
michael@0: 
michael@0: /**
michael@0:  * Misc. front end utilities for apzc management.
michael@0:  * the pref: layers.async-pan-zoom.enabled is true.
michael@0:  */
michael@0: 
michael@0: var APZCObserver = {
michael@0:   _debugEvents: false,
michael@0:   _enabled: false,
michael@0: 
michael@0:   get enabled() {
michael@0:     return this._enabled;
michael@0:   },
michael@0: 
michael@0:   init: function() {
michael@0:     this._enabled = Services.prefs.getBoolPref(kAsyncPanZoomEnabled);
michael@0:     if (!this._enabled) {
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     let os = Services.obs;
michael@0:     os.addObserver(this, "apzc-transform-begin", false);
michael@0: 
michael@0:     Elements.tabList.addEventListener("TabSelect", this, true);
michael@0:     Elements.browsers.addEventListener("pageshow", this, true);
michael@0:     messageManager.addMessageListener("Content:ZoomToRect", this);
michael@0:   },
michael@0: 
michael@0:   shutdown: function shutdown() {
michael@0:     if (!this._enabled) {
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     let os = Services.obs;
michael@0:     os.removeObserver(this, "apzc-transform-begin");
michael@0: 
michael@0:     Elements.tabList.removeEventListener("TabSelect", this, true);
michael@0:     Elements.browsers.removeEventListener("pageshow", this, true);
michael@0:     messageManager.removeMessageListener("Content:ZoomToRect", this);
michael@0:   },
michael@0: 
michael@0:   handleEvent: function APZC_handleEvent(aEvent) {
michael@0:     switch (aEvent.type) {
michael@0:       case 'TabSelect':
michael@0:         this._resetDisplayPort();
michael@0:         break;
michael@0: 
michael@0:       case 'pageshow':
michael@0:         if (aEvent.target != Browser.selectedBrowser.contentDocument) {
michael@0:           break;
michael@0:         }
michael@0:         this._resetDisplayPort();
michael@0:         break;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   observe: function ao_observe(aSubject, aTopic, aData) {
michael@0:     if (aTopic == "apzc-transform-begin") {
michael@0:       // When we're panning, hide the main scrollbars by setting imprecise
michael@0:       // input (which sets a property on the browser which hides the scrollbar
michael@0:       // via CSS).  This reduces jittering from left to right. We may be able
michael@0:       // to get rid of this once we implement axis locking in /gfx APZC.
michael@0:       if (InputSourceHelper.isPrecise) {
michael@0:         InputSourceHelper._imprecise();
michael@0:       }
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   receiveMessage: function(aMessage) {
michael@0:     let json = aMessage.json;
michael@0:     let browser = aMessage.target;
michael@0:     switch (aMessage.name) {
michael@0:       case "Content:ZoomToRect": {
michael@0:         let { presShellId, viewId } = json;
michael@0:         let rect = Rect.fromRect(json.rect);
michael@0:         if (this.isRectZoomedIn(rect, browser.contentViewportBounds)) {
michael@0:           // If we're already zoomed in, zoom out instead.
michael@0:           rect = new Rect(0,0,0,0);
michael@0:         }
michael@0:         let data = [rect.x, rect.y, rect.width, rect.height, presShellId, viewId].join(",");
michael@0:         Services.obs.notifyObservers(null, "apzc-zoom-to-rect", data);
michael@0:       }
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Check to see if the area of the rect visible in the viewport is
michael@0:    * approximately the max area of the rect we can show.
michael@0:    * Based on code from BrowserElementPanning.js
michael@0:    */
michael@0:   isRectZoomedIn: function (aRect, aViewport) {
michael@0:     let overlap = aViewport.intersect(aRect);
michael@0:     let overlapArea = overlap.width * overlap.height;
michael@0:     let availHeight = Math.min(aRect.width * aViewport.height / aViewport.width, aRect.height);
michael@0:     let showing = overlapArea / (aRect.width * availHeight);
michael@0:     let ratioW = (aRect.width / aViewport.width);
michael@0:     let ratioH = (aRect.height / aViewport.height);
michael@0: 
michael@0:     return (showing > 0.9 && (ratioW > 0.9 || ratioH > 0.9));
michael@0:   },
michael@0: 
michael@0:   _resetDisplayPort: function () {
michael@0:     // Start off with something reasonable. The apzc will handle these
michael@0:     // calculations once scrolling starts.
michael@0:     let doc = Browser.selectedBrowser.contentDocument.documentElement;
michael@0:     // While running tests, sometimes this can be null. If we don't have a
michael@0:     // root document, there's no point in setting a scrollable display port.
michael@0:     if (!doc) {
michael@0:       return;
michael@0:     }
michael@0:     let win = Browser.selectedBrowser.contentWindow;
michael@0:     let factor = 0.2;
michael@0:     let portX = 0;
michael@0:     let portY = 0;
michael@0:     let portWidth = ContentAreaObserver.width;
michael@0:     let portHeight = ContentAreaObserver.height;
michael@0: 
michael@0:     if (portWidth < doc.scrollWidth) {
michael@0:       portWidth += ContentAreaObserver.width * factor;
michael@0:       if (portWidth > doc.scrollWidth) {
michael@0:         portWidth = doc.scrollWidth;
michael@0:       }
michael@0:     }
michael@0:     if (portHeight < doc.scrollHeight) {
michael@0:       portHeight += ContentAreaObserver.height * factor;
michael@0:       if (portHeight > doc.scrollHeight) {
michael@0:         portHeight = doc.scrollHeight;
michael@0:       }
michael@0:     }
michael@0:     if (win.scrollX > 0) {
michael@0:       portX -= ContentAreaObserver.width * factor;
michael@0:     }
michael@0:     if (win.scrollY > 0) {
michael@0:       portY -= ContentAreaObserver.height * factor;
michael@0:     }
michael@0:     let cwu = Browser.selectedBrowser.contentWindow
michael@0:                       .QueryInterface(Ci.nsIInterfaceRequestor)
michael@0:                       .getInterface(Ci.nsIDOMWindowUtils);
michael@0:     cwu.setDisplayPortForElement(portX, portY,
michael@0:                                  portWidth, portHeight,
michael@0:                                  Browser.selectedBrowser.contentDocument.documentElement,
michael@0:                                  0);
michael@0:   }
michael@0: };