Bug 847872: Make reflow-on-zoom happen on double-tap only. [r=blassey]

mobile/android/base/locales/en-US/android_strings.dtd

@@ -97,7 +97,7 @@
 <!ENTITY pref_plugins_tap_to_play "Tap to play">
 <!ENTITY pref_plugins_disabled "Disabled">
 <!ENTITY pref_text_size "Text size">
-<!ENTITY pref_reflow_on_zoom2 "Pinch to reflow text">
+<!ENTITY pref_reflow_on_zoom3 "Double tap to reflow text">
 <!ENTITY pref_font_size_tiny "Tiny">
 <!ENTITY pref_font_size_small "Small">
 <!ENTITY pref_font_size_medium "Medium">

mobile/android/base/strings.xml.in

@@ -115,7 +115,7 @@
   <string name="pref_font_size_set">&pref_font_size_set;</string>
   <string name="pref_font_size_adjust_char">&pref_font_size_adjust_char;</string>
   <string name="pref_font_size_preview_text">&pref_font_size_preview_text;</string>
-  <string name="pref_reflow_on_zoom">&pref_reflow_on_zoom2;</string>
+  <string name="pref_reflow_on_zoom">&pref_reflow_on_zoom3;</string>
   <string name="pref_show_product_announcements">&pref_show_product_announcements;</string>
   <string name="pref_sync">&pref_sync;</string>
   <string name="pref_search_suggestions">&pref_search_suggestions;</string>

mobile/android/chrome/content/browser.js

@@ -179,6 +179,14 @@ function fuzzyEquals(a, b) {
   return (Math.abs(a - b) < 1e-6);
 }
 
+/**
+ * Convert a font size from CSS pixels (px) to twenteiths-of-a-point
+ * (twips).
+ */
+function convertFromPxToTwips(aSize) {
+  return (20.0 * 12.0 * (aSize/16.0));
+}
+
 #ifdef MOZ_CRASHREPORTER
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "CrashReporter",
@@ -2549,16 +2557,45 @@ Tab.prototype = {
     }
   },
 
+  /**
+   * Retrieves the font size in twips for a given element.
+   */
+  getFontSizeInTwipsFor: function(aElement) {
+    // GetComputedStyle should always give us CSS pixels for a font size.
+    let fontSizeStr = this.window.getComputedStyle(aElement)['fontSize'];
+    let fontSize = fontSizeStr.slice(0, -2);
+    // This is in px, so we want to convert it to points then to twips.
+    return convertFromPxToTwips(fontSize);
+  },
+
+  /**
+   * This returns the zoom necessary to match the font size of an element to
+   * the minimum font size specified by the browser.zoom.reflowOnZoom.minFontSizeTwips
+   * preference.
+   */
+  getZoomToMinFontSize: function(aElement) {
+    let currentZoom = this._zoom;
+    let minFontSize = Services.prefs.getIntPref("browser.zoom.reflowZoom.minFontSizeTwips");
+    let curFontSize = this.getFontSizeInTwipsFor(aElement);
+    if (!fuzzyEquals(curFontSize*(currentZoom), minFontSize)) {
+      return 1.0 + minFontSize / curFontSize;
+    }
+
+    return 1.0;
+  },
+
   performReflowOnZoom: function(aViewport) {
-      let viewportWidth = gScreenWidth / aViewport.zoom;
+      let zoom = this._drawZoom ? this._drawZoom : aViewport.zoom;
+
+      let viewportWidth = gScreenWidth / zoom;
       let reflozTimeout = Services.prefs.getIntPref("browser.zoom.reflowZoom.reflowTimeout");
 
       if (gReflowPending) {
         clearTimeout(gReflowPending);
       }
 
-      // We add in a bit of fudge just so that the end characters don't accidentally
+      // We add in a bit of fudge just so that the end characters
-      // get clipped. 15px is an arbitrary choice.
+      // don't accidentally get clipped. 15px is an arbitrary choice.
       gReflowPending = setTimeout(doChangeMaxLineBoxWidth,
                                   reflozTimeout,
                                   viewportWidth - 15);
@@ -2913,7 +2950,21 @@ Tab.prototype = {
 
     // Adjust the max line box width to be no more than the viewport width, but
     // only if the reflow-on-zoom preference is enabled.
-    let isZooming = Math.abs(aViewport.zoom - this._zoom) >= 1e-6;
+    let isZooming = !fuzzyEquals(aViewport.zoom, this._zoom);
+    if (BrowserApp.selectedTab.reflozPinchSeen &&
+        isZooming && aViewport.zoom < 1.0) {
+      // In this case, we want to restore the max line box width,
+      // because we are pinch-zooming to zoom out.
+      BrowserEventHandler.resetMaxLineBoxWidth();
+      BrowserApp.selectedTab.reflozPinchSeen = false;
+    } else if (BrowserApp.selectedTab.reflozPinchSeen &&
+               isZooming) {
+      // In this case, the user pinch-zoomed in, so we don't want to
+      // preserve position as we would with reflow-on-zoom.
+      BrowserApp.selectedTab.probablyNeedRefloz = false;
+      BrowserApp.selectedTab._mReflozPoint = null;
+    }
+
     if (isZooming &&
         BrowserEventHandler.mReflozPref &&
         BrowserApp.selectedTab._mReflozPoint &&
@@ -3812,10 +3863,15 @@ var BrowserEventHandler = {
   },
 
   resetMaxLineBoxWidth: function() {
-    let webNav = window.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIWebNavigation);
+    BrowserApp.selectedTab.probablyNeedRefloz = false;
-    let docShell = webNav.QueryInterface(Ci.nsIDocShell);
+
-    let docViewer = docShell.contentViewer.QueryInterface(Ci.nsIMarkupDocumentViewer);
+    if (gReflowPending) {
-    docViewer.changeMaxLineBoxWidth(0);
+      clearTimeout(gReflowPending);
+    }
+
+    let reflozTimeout = Services.prefs.getIntPref("browser.zoom.reflowZoom.reflowTimeout");
+    gReflowPending = setTimeout(doChangeMaxLineBoxWidth,
+                                reflozTimeout, 0);
   },
 
   updateReflozPref: function() {
@@ -4046,6 +4102,18 @@ var BrowserEventHandler = {
   onDoubleTap: function(aData) {
     let data = JSON.parse(aData);
 
+    // We only want to do this if reflow-on-zoom is enabled.
+    if (BrowserEventHandler.mReflozPref &&
+       !BrowserApp.selectedTab._mReflozPoint) {
+     let data = JSON.parse(aData);
+     let zoomPointX = data.x;
+     let zoomPointY = data.y;
+
+     BrowserApp.selectedTab._mReflozPoint = { x: zoomPointX, y: zoomPointY,
+       range: BrowserApp.selectedBrowser.contentDocument.caretPositionFromPoint(zoomPointX, zoomPointY) };
+       BrowserApp.selectedTab.probablyNeedRefloz = true;
+    }
+
     let zoom = BrowserApp.selectedTab._zoom;
     let element = ElementTouchHelper.anyElementFromPoint(data.x, data.y);
     if (!element) {
@@ -4068,6 +4136,10 @@ var BrowserEventHandler = {
    */
   _zoomToElement: function(aElement, aClickY = -1, aCanZoomOut = true, aCanScrollHorizontally = true) {
     const margin = 15;
+
+    // This is really only used for reflow-on-zoom.
+    let zoomFactor = BrowserApp.selectedTab.getZoomToMinFontSize(aElement);
+
     let rect = ElementTouchHelper.getBoundingContentRect(aElement);
 
     let viewport = BrowserApp.selectedTab.getViewport();
@@ -4077,12 +4149,20 @@ var BrowserEventHandler = {
                          rect.h);
     // constrict the rect to the screen's right edge
     bRect.width = Math.min(bRect.width, viewport.cssPageRight - bRect.x);
+    if (BrowserEventHandler.mReflozPref) {
+      bRect.width = zoomFactor == 1.0 ? bRect.width : gScreenWidth / zoomFactor;
+      bRect.height = zoomFactor == 1.0 ? bRect.height : bRect.height / zoomFactor;
+    }
 
     // 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 (this._isRectZoomedIn(bRect, viewport)) {
+    
-      if (aCanZoomOut)
+    if ((BrowserEventHandler.mReflozPref && zoomFactor == 1.0) ||
+        this._isRectZoomedIn(bRect, viewport)) {
+      if (aCanZoomOut) {
         this._zoomOut();
+      }
+
       return;
     }