Fix usage of LayoutUnits and snapping for scrolling in RenderBox

https://bugs.webkit.org/show_bug.cgi?id=83073

Reviewed by Eric Seidel.

Fix usage of LayoutUnits and snapping/rounding logic in RenderBox.

No new tests, no change in functionality.

* rendering/RenderBox.cpp:
(WebCore::RenderBox::scrollWidth):
Change scrollWidth to properly pixel snap values.

(WebCore::RenderBox::scrollHeight):
Change scrollHeight to properly pixel snap values.

(WebCore::RenderBox::scrolledContentOffset):
Change to return IntSize to match function definition.

(WebCore::RenderBox::cachedSizeForOverflowClip):
Changed cachedSizeForOverflowClip to LayoutSize as the overflow and clip
rects all have subpixel precision.

* rendering/RenderBox.h:
(WebCore::RenderBox::pixelSnappedWidth):
(WebCore::RenderBox::pixelSnappedHeight):
Removed FIXME comment as the implementation

(WebCore::RenderBox::minYLayoutOverflow):
(WebCore::RenderBox::maxYLayoutOverflow):
(WebCore::RenderBox::minXLayoutOverflow):
(WebCore::RenderBox::maxXLayoutOverflow):
Added static_cast for border values.

(WebCore::RenderBox::hasVisualOverflow):
Changed to compare two pixel snapped values as we don't want to indicate
overflow in cases where the the size is rounded down resulting in no
visual overflow.


Canonical link: https://commits.webkit.org/100560@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@113223 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/ChangeLog

@@ -1,3 +1,44 @@
+2012-04-04  Emil A Eklund  <eae@chromium.org>
+
+        Fix usage of LayoutUnits and snapping for scrolling in RenderBox
+        https://bugs.webkit.org/show_bug.cgi?id=83073
+
+        Reviewed by Eric Seidel.
+
+        Fix usage of LayoutUnits and snapping/rounding logic in RenderBox.
+
+        No new tests, no change in functionality.
+
+        * rendering/RenderBox.cpp:
+        (WebCore::RenderBox::scrollWidth):
+        Change scrollWidth to properly pixel snap values.
+
+        (WebCore::RenderBox::scrollHeight):
+        Change scrollHeight to properly pixel snap values.
+
+        (WebCore::RenderBox::scrolledContentOffset):
+        Change to return IntSize to match function definition.
+
+        (WebCore::RenderBox::cachedSizeForOverflowClip):
+        Changed cachedSizeForOverflowClip to LayoutSize as the overflow and clip
+        rects all have subpixel precision.
+
+        * rendering/RenderBox.h:
+        (WebCore::RenderBox::pixelSnappedWidth):
+        (WebCore::RenderBox::pixelSnappedHeight):
+        Removed FIXME comment as the implementation 
+
+        (WebCore::RenderBox::minYLayoutOverflow):
+        (WebCore::RenderBox::maxYLayoutOverflow):
+        (WebCore::RenderBox::minXLayoutOverflow):
+        (WebCore::RenderBox::maxXLayoutOverflow):
+        Added static_cast for border values.
+
+        (WebCore::RenderBox::hasVisualOverflow):
+        Changed to compare two pixel snapped values as we don't want to indicate
+        overflow in cases where the the size is rounded down resulting in no
+        visual overflow.
+
 2012-04-04  Emil A Eklund  <eae@chromium.org>
 
         Fix types for location, size and rect calculations for render objects

Source/WebCore/rendering/RenderBox.cpp

@@ -502,7 +502,7 @@ int RenderBox::scrollWidth() const
     // For objects with visible overflow, this matches IE.
     // FIXME: Need to work right with writing modes.
     if (style()->isLeftToRightDirection())
-        return max(clientWidth(), maxXLayoutOverflow() - borderLeft());
+        return snapSizeToPixel(max(clientWidth(), maxXLayoutOverflow() - borderLeft()), clientLeft());
     return clientWidth() - min(0, minXLayoutOverflow() - borderLeft());
 }
 
@@ -512,7 +512,7 @@ int RenderBox::scrollHeight() const
         return layer()->scrollHeight();
     // For objects with visible overflow, this matches IE.
     // FIXME: Need to work right with writing modes.
-    return max(pixelSnappedClientHeight(), maxYLayoutOverflow() - borderTop());
+    return snapSizeToPixel(max(clientHeight(), maxYLayoutOverflow() - borderTop()), clientTop());
 }
 
 int RenderBox::scrollLeft() const
@@ -764,7 +764,7 @@ IntSize RenderBox::scrolledContentOffset() const
     // If we have no layer, it means that we have no overflowing content as we lazily
     // allocate it on demand. Thus we don't have any scroll offset.
     ASSERT(!requiresLayerForOverflowClip());
-    return LayoutSize();
+    return IntSize();
 }
 
 typedef HashMap<const RenderBox*, LayoutSize> RendererSizeCache;
@@ -774,7 +774,7 @@ static RendererSizeCache& cachedSizeForOverflowClipMap()
     return cachedSizeForOverflowClipMap;
 }
 
-IntSize RenderBox::cachedSizeForOverflowClip() const
+LayoutSize RenderBox::cachedSizeForOverflowClip() const
 {
     ASSERT(hasOverflowClip());
     if (hasLayer())

Source/WebCore/rendering/RenderBox.h

@@ -56,9 +56,8 @@ class RenderBox : public RenderBoxModelObject {
     LayoutUnit width() const { return m_frameRect.width(); }
     LayoutUnit height() const { return m_frameRect.height(); }
 
-    // FIXME: The implementation for these functions will change once we move to subpixel layout. See bug 60318.
-    int pixelSnappedWidth() const { return m_frameRect.width(); }
-    int pixelSnappedHeight() const { return m_frameRect.height(); }
+    int pixelSnappedWidth() const { return m_frameRect.pixelSnappedWidth(); }
+    int pixelSnappedHeight() const { return m_frameRect.pixelSnappedHeight(); }
 
     // These represent your location relative to your container as a physical offset.
     // In layout related methods you almost always want the logical location (e.g. x() and y()).
@@ -159,10 +158,10 @@ class RenderBox : public RenderBoxModelObject {
     // but it is on the right in vertical-rl.
     LayoutRect layoutOverflowRect() const { return m_overflow ? m_overflow->layoutOverflowRect() : clientBoxRect(); }
     IntRect pixelSnappedLayoutOverflowRect() const { return pixelSnappedIntRect(layoutOverflowRect()); }
-    LayoutUnit minYLayoutOverflow() const { return m_overflow? m_overflow->minYLayoutOverflow() : borderTop(); }
-    LayoutUnit maxYLayoutOverflow() const { return m_overflow ? m_overflow->maxYLayoutOverflow() : borderTop() + clientHeight(); }
-    LayoutUnit minXLayoutOverflow() const { return m_overflow ? m_overflow->minXLayoutOverflow() : borderLeft(); }
-    LayoutUnit maxXLayoutOverflow() const { return m_overflow ? m_overflow->maxXLayoutOverflow() : borderLeft() + clientWidth(); }
+    LayoutUnit minYLayoutOverflow() const { return m_overflow? m_overflow->minYLayoutOverflow() : static_cast<LayoutUnit>(borderTop()); }
+    LayoutUnit maxYLayoutOverflow() const { return m_overflow ? m_overflow->maxYLayoutOverflow() : static_cast<LayoutUnit>(borderTop()) + clientHeight(); }
+    LayoutUnit minXLayoutOverflow() const { return m_overflow ? m_overflow->minXLayoutOverflow() : static_cast<LayoutUnit>(borderLeft()); }
+    LayoutUnit maxXLayoutOverflow() const { return m_overflow ? m_overflow->maxXLayoutOverflow() : static_cast<LayoutUnit>(borderLeft()) + clientWidth(); }
     LayoutSize maxLayoutOverflow() const { return LayoutSize(maxXLayoutOverflow(), maxYLayoutOverflow()); }
     LayoutUnit logicalLeftLayoutOverflow() const { return style()->isHorizontalWritingMode() ? minXLayoutOverflow() : minYLayoutOverflow(); }
     LayoutUnit logicalRightLayoutOverflow() const { return style()->isHorizontalWritingMode() ? maxXLayoutOverflow() : maxYLayoutOverflow(); }
@@ -450,13 +449,13 @@ class RenderBox : public RenderBoxModelObject {
     LayoutRect layoutOverflowRectForPropagation(RenderStyle*) const;
 
     RenderOverflow* hasRenderOverflow() const { return m_overflow.get(); }    
-    bool hasVisualOverflow() const { return m_overflow && !borderBoxRect().contains(m_overflow->visualOverflowRect()); }
+    bool hasVisualOverflow() const { return m_overflow && !borderBoxRect().contains(pixelSnappedIntRect(m_overflow->visualOverflowRect())); }
 
     virtual bool needsPreferredWidthsRecalculation() const;
     virtual void computeIntrinsicRatioInformation(FloatSize& /* intrinsicSize */, double& /* intrinsicRatio */, bool& /* isPercentageIntrinsicSize */) const { }
 
     IntSize scrolledContentOffset() const;
-    IntSize cachedSizeForOverflowClip() const;
+    LayoutSize cachedSizeForOverflowClip() const;
     void updateCachedSizeForOverflowClip();
     void clearCachedSizeForOverflowClip();