The Tor Browser: mobile/android/chrome/content/ZoomHelper.js@b8a032363ba2 (annotated)

mobile/android/chrome/content/ZoomHelper.js@b8a032363ba2 (annotated)

mobile/android/chrome/content/ZoomHelper.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

 /* 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";
 var ZoomHelper = {
   zoomInAndSnapToRange: function(aRange) {
     // aRange is always non-null here, since a check happened previously.
     let viewport = BrowserApp.selectedTab.getViewport();
     let fudge = 15; // Add a bit of fudge.
     let boundingElement = aRange.offsetNode;
     while (!boundingElement.getBoundingClientRect && boundingElement.parentNode) {
       boundingElement = boundingElement.parentNode;
     }
     let rect = ElementTouchHelper.getBoundingContentRect(boundingElement);
     let drRect = aRange.getClientRect();
     let scrollTop =
       BrowserApp.selectedBrowser.contentDocument.documentElement.scrollTop ||
       BrowserApp.selectedBrowser.contentDocument.body.scrollTop;
     // We subtract half the height of the viewport so that we can (ideally)
     // center the area of interest on the screen.
     let topPos = scrollTop + drRect.top - (viewport.cssHeight / 2.0);
     // Factor in the border and padding
     let boundingStyle = window.getComputedStyle(boundingElement);
     let leftAdjustment = parseInt(boundingStyle.paddingLeft) +
                          parseInt(boundingStyle.borderLeftWidth);
     BrowserApp.selectedTab._mReflozPositioned = true;
     rect.type = "Browser:ZoomToRect";
     rect.x = Math.max(viewport.cssPageLeft, rect.x  - fudge + leftAdjustment);
     rect.y = Math.max(topPos, viewport.cssPageTop);
     rect.w = viewport.cssWidth;
     rect.h = viewport.cssHeight;
     rect.animate = false;
     sendMessageToJava(rect);
     BrowserApp.selectedTab._mReflozPoint = null;
   },
   zoomOut: function() {
     BrowserEventHandler.resetMaxLineBoxWidth();
     sendMessageToJava({ type: "Browser:ZoomToPageWidth" });
   },
   isRectZoomedIn: function(aRect, aViewport) {
     // This function checks to see if the area of the rect visible in the
     // viewport (i.e. the "overlapArea" variable below) is approximately
     // the max area of the rect we can show. It also checks that the rect
     // is actually on-screen by testing the left and right edges of the rect.
     // In effect, this tells us whether or not zooming in to this rect
     // will significantly change what the user is seeing.
     const minDifference = -20;
     const maxDifference = 20;
     const maxZoomAllowed = 4; // keep this in sync with mobile/android/base/ui/PanZoomController.MAX_ZOOM
     let vRect = new Rect(aViewport.cssX, aViewport.cssY, aViewport.cssWidth, aViewport.cssHeight);
     let overlap = vRect.intersect(aRect);
     let overlapArea = overlap.width * overlap.height;
     let availHeight = Math.min(aRect.width * vRect.height / vRect.width, aRect.height);
     let showing = overlapArea / (aRect.width * availHeight);
     let dw = (aRect.width - vRect.width);
     let dx = (aRect.x - vRect.x);
     if (fuzzyEquals(aViewport.zoom, maxZoomAllowed) && overlap.width / aRect.width > 0.9) {
       // we're already at the max zoom and the block is not spilling off the side of the screen so that even
       // if the block isn't taking up most of the viewport we can't pan/zoom in any more. return true so that we zoom out
       return true;
     }
     return (showing > 0.9 &&
             dx > minDifference && dx < maxDifference &&
             dw > minDifference && dw < maxDifference);
   },
   /* Zoom to an element, optionally keeping a particular part of it
    * in view if it is really tall.
    */
   zoomToElement: function(aElement, aClickY = -1, aCanZoomOut = true, aCanScrollHorizontally = true) {
     let rect = ElementTouchHelper.getBoundingContentRect(aElement);
     ZoomHelper.zoomToRect(rect, aClickY, aCanZoomOut, aCanScrollHorizontally, aElement);
   },
   zoomToRect: function(aRect, aClickY = -1, aCanZoomOut = true, aCanScrollHorizontally = true, aElement) {
     const margin = 15;
     if(!aRect.h || !aRect.w) {
       aRect.h = aRect.height;
       aRect.w = aRect.width;
     }
     let viewport = BrowserApp.selectedTab.getViewport();
     let bRect = new Rect(aCanScrollHorizontally ? Math.max(viewport.cssPageLeft, aRect.x - margin) : viewport.cssX,
                          aRect.y,
                          aCanScrollHorizontally ? aRect.w + 2 * margin : viewport.cssWidth,
                          aRect.h);
     // constrict the rect to the screen's right edge
     bRect.width = Math.min(bRect.width, viewport.cssPageRight - bRect.x);
     // if the rect is already taking up most of the visible area and is stretching the
     // width of the page, then we want to zoom out instead.
     if (aElement) {
       if (BrowserEventHandler.mReflozPref) {
         let zoomFactor = BrowserApp.selectedTab.getZoomToMinFontSize(aElement);
         bRect.width = zoomFactor <= 1.0 ? bRect.width : gScreenWidth / zoomFactor;
         bRect.height = zoomFactor <= 1.0 ? bRect.height : bRect.height / zoomFactor;
         if (zoomFactor == 1.0 || ZoomHelper.isRectZoomedIn(bRect, viewport)) {
           if (aCanZoomOut) {
             ZoomHelper.zoomOut();
           }
           return;
         }
       } else if (ZoomHelper.isRectZoomedIn(bRect, viewport)) {
         if (aCanZoomOut) {
           ZoomHelper.zoomOut();
         }
         return;
       }
     }
     let rect = {};
     rect.type = "Browser:ZoomToRect";
     rect.x = bRect.x;
     rect.y = bRect.y;
     rect.w = bRect.width;
     rect.h = Math.min(bRect.width * viewport.cssHeight / viewport.cssWidth, bRect.height);
     if (aClickY >= 0) {
       // if the block we're zooming to is really tall, and we want to keep a particular
       // part of it in view, then adjust the y-coordinate of the target rect accordingly.
       // the 1.2 multiplier is just a little fuzz to compensate for bRect including horizontal
       // margins but not vertical ones.
       let cssTapY = viewport.cssY + aClickY;
       if ((bRect.height > rect.h) && (cssTapY > rect.y + (rect.h * 1.2))) {
         rect.y = cssTapY - (rect.h / 2);
       }
     }
     if (rect.w > viewport.cssWidth || rect.h > viewport.cssHeight) {
       BrowserEventHandler.resetMaxLineBoxWidth();
     }
     sendMessageToJava(rect);
   },
 };