Bug 1016682 - Store CSS viewport size as floating-point to avoid rounding errors. r=tn

content/base/public/nsViewportInfo.h

@@ -32,7 +32,7 @@ class MOZ_STACK_CLASS nsViewportInfo
       mAllowZoom(aAllowZoom),
       mAllowDoubleTapZoom(aAllowDoubleTapZoom)
     {
-        mSize = mozilla::gfx::RoundedToInt(mozilla::ScreenSize(aDisplaySize) / mDefaultZoom);
+        mSize = mozilla::ScreenSize(aDisplaySize) / mDefaultZoom;
         mozilla::CSSToLayoutDeviceScale pixelRatio(1.0f);
         mMinZoom = pixelRatio * kViewportMinScale;
         mMaxZoom = pixelRatio * kViewportMaxScale;
@@ -42,7 +42,7 @@ class MOZ_STACK_CLASS nsViewportInfo
     nsViewportInfo(const mozilla::CSSToScreenScale& aDefaultZoom,
                    const mozilla::CSSToScreenScale& aMinZoom,
                    const mozilla::CSSToScreenScale& aMaxZoom,
-                   const mozilla::CSSIntSize& aSize,
+                   const mozilla::CSSSize& aSize,
                    bool aAutoSize,
                    bool aAllowZoom,
                    bool aAllowDoubleTapZoom) :
@@ -62,7 +62,7 @@ class MOZ_STACK_CLASS nsViewportInfo
     mozilla::CSSToScreenScale GetMinZoom() { return mMinZoom; }
     mozilla::CSSToScreenScale GetMaxZoom() { return mMaxZoom; }
 
-    mozilla::CSSIntSize GetSize() { return mSize; }
+    mozilla::CSSSize GetSize() { return mSize; }
 
     bool IsAutoSizeEnabled() { return mAutoSize; }
     bool IsZoomAllowed() { return mAllowZoom; }
@@ -90,7 +90,7 @@ class MOZ_STACK_CLASS nsViewportInfo
     mozilla::CSSToScreenScale mMaxZoom;
 
     // The size of the viewport, specified by the <meta name="viewport"> tag.
-    mozilla::CSSIntSize mSize;
+    mozilla::CSSSize mSize;
 
     // Whether or not we should automatically size the viewport to the device's
     // width. This is true if the document has been optimized for mobile, and

content/base/src/nsDocument.cpp

@@ -7625,11 +7625,11 @@ nsDocument::GetViewportInfo(const ScreenIntSize& aDisplaySize)
   }
   case Specified:
   default:
-    CSSIntSize size = mViewportSize;
+    CSSSize size = mViewportSize;
 
     if (!mValidWidth) {
       if (mValidHeight && !aDisplaySize.IsEmpty()) {
-        size.width = int32_t(size.height * aDisplaySize.width / aDisplaySize.height);
+        size.width = size.height * aDisplaySize.width / aDisplaySize.height;
       } else {
         size.width = Preferences::GetInt("browser.viewport.desktopWidth",
                                          kViewportDefaultScreenWidth);
@@ -7638,7 +7638,7 @@ nsDocument::GetViewportInfo(const ScreenIntSize& aDisplaySize)
 
     if (!mValidHeight) {
       if (!aDisplaySize.IsEmpty()) {
-        size.height = int32_t(size.width * aDisplaySize.height / aDisplaySize.width);
+        size.height = size.width * aDisplaySize.height / aDisplaySize.width;
       } else {
         size.height = size.width;
       }
@@ -7654,28 +7654,28 @@ nsDocument::GetViewportInfo(const ScreenIntSize& aDisplaySize)
     if (mAutoSize) {
       // aDisplaySize is in screen pixels; convert them to CSS pixels for the viewport size.
       CSSToScreenScale defaultPixelScale = pixelRatio * LayoutDeviceToScreenScale(1.0f);
-      size = mozilla::gfx::RoundedToInt(ScreenSize(aDisplaySize) / defaultPixelScale);
+      size = ScreenSize(aDisplaySize) / defaultPixelScale;
     }
 
-    size.width = clamped(size.width, kViewportMinSize.width, kViewportMaxSize.width);
+    size.width = clamped(size.width, float(kViewportMinSize.width), float(kViewportMaxSize.width));
 
     // Also recalculate the default zoom, if it wasn't specified in the metadata,
     // and the width is specified.
     if (mScaleStrEmpty && !mWidthStrEmpty) {
-      CSSToScreenScale defaultScale(float(aDisplaySize.width) / float(size.width));
+      CSSToScreenScale defaultScale(float(aDisplaySize.width) / size.width);
       scaleFloat = (scaleFloat > defaultScale) ? scaleFloat : defaultScale;
     }
 
-    size.height = clamped(size.height, kViewportMinSize.height, kViewportMaxSize.height);
+    size.height = clamped(size.height, float(kViewportMinSize.height), float(kViewportMaxSize.height));
 
     // We need to perform a conversion, but only if the initial or maximum
     // scale were set explicitly by the user.
     if (mValidScaleFloat) {
-      CSSIntSize displaySize = RoundedToInt(ScreenSize(aDisplaySize) / scaleFloat);
+      CSSSize displaySize = ScreenSize(aDisplaySize) / scaleFloat;
       size.width = std::max(size.width, displaySize.width);
       size.height = std::max(size.height, displaySize.height);
     } else if (mValidMaxScale) {
-      CSSIntSize displaySize = RoundedToInt(ScreenSize(aDisplaySize) / scaleMaxFloat);
+      CSSSize displaySize = ScreenSize(aDisplaySize) / scaleMaxFloat;
       size.width = std::max(size.width, displaySize.width);
       size.height = std::max(size.height, displaySize.height);
     }

content/base/src/nsDocument.h

@@ -1692,7 +1692,7 @@ private:
   mozilla::LayoutDeviceToScreenScale mScaleFloat;
   mozilla::CSSToLayoutDeviceScale mPixelRatio;
   bool mAutoSize, mAllowZoom, mAllowDoubleTapZoom, mValidScaleFloat, mValidMaxScale, mScaleStrEmpty, mWidthStrEmpty;
-  mozilla::CSSIntSize mViewportSize;
+  mozilla::CSSSize mViewportSize;
 
   nsrefcnt mStackRefCnt;
   bool mNeedsReleaseAfterStackRefCntRelease;

dom/base/nsDOMWindowUtils.cpp

@@ -318,8 +318,9 @@ nsDOMWindowUtils::GetViewportInfo(uint32_t aDisplayWidth,
   *aAllowZoom = info.IsZoomAllowed();
   *aMinZoom = info.GetMinZoom().scale;
   *aMaxZoom = info.GetMaxZoom().scale;
-  *aWidth = info.GetSize().width;
-  *aHeight = info.GetSize().height;
+  CSSIntSize size = gfx::RoundedToInt(info.GetSize());
+  *aWidth = size.width;
+  *aHeight = size.height;
   *aAutoSize = info.IsAutoSizeEnabled();
   return NS_OK;
 }