Bug 1180267 - Ensure that the desktop-mode viewport for Fennec is based on a 980 CSS pixel width rather than the screen size. r=snorp

--HG--
extra : commitid : EDmJyKrfnzt

dom/base/nsDocument.cpp

@@ -7904,8 +7904,12 @@ nsDocument::GetViewportInfo(const ScreenIntSize& aDisplaySize)
   nsPIDOMWindow* win = GetWindow();
   if (win && win->IsDesktopModeViewport())
   {
-    return nsViewportInfo(aDisplaySize,
-                          defaultScale,
+    float viewportWidth = gfxPrefs::DesktopViewportWidth() / fullZoom;
+    float scaleToFit = aDisplaySize.width / viewportWidth;
+    float aspectRatio = (float)aDisplaySize.height / aDisplaySize.width;
+    ScreenSize viewportSize(viewportWidth, viewportWidth * aspectRatio);
+    return nsViewportInfo(RoundedToInt(viewportSize),
+                          CSSToScreenScale(scaleToFit),
                           /*allowZoom*/false,
                           /*allowDoubleTapZoom*/ false);
   }
@@ -8060,8 +8064,7 @@ nsDocument::GetViewportInfo(const ScreenIntSize& aDisplaySize)
         // Stretch CSS pixel size of viewport to keep device pixel size
         // unchanged after full zoom applied.
         // See bug 974242.
-        size.width = Preferences::GetInt("browser.viewport.desktopWidth",
-                                         kViewportDefaultScreenWidth) / fullZoom;
+        size.width = gfxPrefs::DesktopViewportWidth() / fullZoom;
       }
     }
 

dom/base/nsViewportInfo.h

@@ -16,7 +16,6 @@ static const mozilla::LayoutDeviceToScreenScale kViewportMinScale(0.0f);
 static const mozilla::LayoutDeviceToScreenScale kViewportMaxScale(10.0f);
 static const mozilla::CSSIntSize kViewportMinSize(200, 40);
 static const mozilla::CSSIntSize kViewportMaxSize(10000, 10000);
-static const int32_t  kViewportDefaultScreenWidth = 980;
 
 /**
  * Information retrieved from the <meta name="viewport"> tag. See

gfx/thebes/gfxPrefs.h

@@ -187,6 +187,8 @@ private:
   DECL_GFX_PREF(Live, "apz.y_stationary_size_multiplier",      APZYStationarySizeMultiplier, float, 3.5f);
   DECL_GFX_PREF(Live, "apz.zoom_animation_duration_ms",        APZZoomAnimationDuration, int32_t, 250);
 
+  DECL_GFX_PREF(Live, "browser.viewport.desktopWidth",         DesktopViewportWidth, int32_t, 980);
+
   DECL_GFX_PREF(Live, "dom.meta-viewport.enabled",             MetaViewportEnabled, bool, false);
   DECL_GFX_PREF(Once, "dom.vr.enabled",                        VREnabled, bool, false);
   DECL_GFX_PREF(Once, "dom.vr.oculus.enabled",                 VROculusEnabled, bool, true);