Bug 941592 - Make double-tap zoom action depend on current zoom level [r=jimm]

browser/metro/base/content/apzc.js

@@ -32,10 +32,10 @@ var APZCObserver = {
 
     // Fired by ContentAreaObserver
     window.addEventListener("SizeChanged", this, true);
-
     Elements.tabList.addEventListener("TabSelect", this, true);
-    Elements.tabList.addEventListener("TabOpen", this, true);
-    Elements.tabList.addEventListener("TabClose", this, true);
+    Elements.browsers.addEventListener("pageshow", this, true);
+    messageManager.addMessageListener("Browser:ContentScroll", this);
+    messageManager.addMessageListener("Content:ZoomToRect", this);
   },
 
   shutdown: function shutdown() {
@@ -47,10 +47,10 @@ var APZCObserver = {
     os.removeObserver(this, "apzc-transform-begin");
 
     window.removeEventListener("SizeChanged", this, true);
-
     Elements.tabList.removeEventListener("TabSelect", this, true);
-    Elements.tabList.removeEventListener("TabOpen", this, true);
-    Elements.tabList.removeEventListener("TabClose", this, true);
+    Elements.browsers.removeEventListener("pageshow", this, true);
+    messageManager.removeMessageListener("Browser:ContentScroll", this);
+    messageManager.removeMessageListener("Content:ZoomToRect", this);
   },
 
   handleEvent: function APZC_handleEvent(aEvent) {
@@ -66,20 +66,6 @@ var APZCObserver = {
         }
         this._resetDisplayPort();
         break;
-
-      case 'TabOpen': {
-        let browser = aEvent.originalTarget.linkedBrowser;
-        browser.addEventListener("pageshow", this, true);
-        // Register for notifications from content about scroll actions.
-        browser.messageManager.addMessageListener("Browser:ContentScroll", this);
-        break;
-      }
-      case 'TabClose': {
-        let browser = aEvent.originalTarget.linkedBrowser;
-        browser.removeEventListener("pageshow", this, true);
-        browser.messageManager.removeMessageListener("Browser:ContentScroll", this);
-        break;
-      }
     }
   },
 
@@ -97,6 +83,7 @@ var APZCObserver = {
 
   receiveMessage: function(aMessage) {
     let json = aMessage.json;
+    let browser = aMessage.target;
     switch (aMessage.name) {
        // Content notifies us here (syncronously) if it has scrolled
        // independent of the apz. This can happen in a lot of
@@ -108,9 +95,35 @@ var APZCObserver = {
         Services.obs.notifyObservers(null, "apzc-scroll-offset-changed", data);
         break;
       }
+      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.

browser/metro/base/content/bindings/browser.xml

@@ -174,8 +174,8 @@
             }
 
             return {
-              x: (aClientX + scrollX - bcr.left) / scale,
-              y: (aClientY + scrollY - bcr.top) / scale
+              x: (aClientX - bcr.left) / scale + scrollX,
+              y: (aClientY - bcr.top) / scale + scrollY
             };
           ]]>
         </body>
@@ -204,11 +204,12 @@
             }
 
             let bcr = this.getBoundingClientRect();
+            let clientRect = Rect.fromRect(aClientRect);
             return new Rect(
-              (aClientRect.x + scrollX - bcr.left) / scale,
-              (aClientRect.y + scrollY - bcr.top) / scale,
-              aClientRect.width / scale,
-              aClientRect.height / scale
+              (clientRect.x - bcr.left) / scale + scrollX,
+              (clientRect.y - bcr.top) / scale + scrollY,
+              clientRect.width / scale,
+              clientRect.height / scale
             );
           ]]>
         </body>

browser/metro/base/content/contenthandlers/Content.js

@@ -116,7 +116,6 @@ function getOverflowContentBoundingRect(aElement) {
  */
 let Content = {
   _debugEvents: false,
-  _isZoomedIn: false,
 
   get formAssistant() {
     delete this.formAssistant;
@@ -145,7 +144,6 @@ let Content = {
     addEventListener("DOMAutoComplete", this, false);
     addEventListener("DOMFormHasPassword", this, false);
     addEventListener("blur", this, false);
-    addEventListener("pagehide", this, false);
     // Attach a listener to watch for "click" events bubbling up from error
     // pages and other similar page. This lets us fix bugs like 401575 which
     // require error page UI to do privileged things, without letting error
@@ -210,10 +208,6 @@ let Content = {
         LoginManagerContent.onUsernameInput(aEvent);
         break;
 
-      case "pagehide":
-        this._isZoomedIn = false;
-        break;
-
       case "touchstart":
         this._onTouchStart(aEvent);
         break;
@@ -381,11 +375,6 @@ let Content = {
   },
 
   _onDoubleTap: function (aX, aY) {
-    if (this._isZoomedIn) {
-      this._zoomOut();
-      return;
-    }
-
     let { element } = Content.getCurrentWindowAndOffset(aX, aY);
     while (element && !this._shouldZoomToElement(element)) {
       element = element.parentNode;
@@ -404,14 +393,12 @@ let Content = {
   _zoomOut: function() {
     let rect = new Rect(0,0,0,0);
     this._zoomToRect(rect);
-    this._isZoomedIn = false;
   },
 
   _zoomToElement: function(aElement) {
     let rect = getBoundingContentRect(aElement);
     this._inflateRect(rect, kZoomToElementMargin);
     this._zoomToRect(rect);
-    this._isZoomedIn = true;
   },
 
   _inflateRect: function(aRect, aMargin) {
@@ -426,13 +413,11 @@ let Content = {
     let viewId = utils.getViewId(content.document.documentElement);
     let presShellId = {};
     utils.getPresShellId(presShellId);
-    let zoomData = [aRect.x,
-                    aRect.y,
-                    aRect.width,
-                    aRect.height,
-                    presShellId.value,
-                    viewId].join(",");
-    Services.obs.notifyObservers(null, "apzc-zoom-to-rect", zoomData);
+    sendAsyncMessage("Content:ZoomToRect", {
+      rect: aRect,
+      presShellId: presShellId.value,
+      viewId: viewId,
+    });
   },
 
   _shouldZoomToElement: function(aElement) {