2008-12-11 Cameron Zwarich <zwarich@apple.com>

        Reviewed by Dave Hyatt.

        Bug 21256: REGRESSION (r36906): horizontally repeating image leaves ghosts when vertical scrolling
        <https://bugs.webkit.org/show_bug.cgi?id=21256>
        <rdar://problem/6362978>

        The ScrollView refactoring in r36906 caused the ScrollView and the
        platform widget to disagree about whether optimizing scrolling via
        blitting is allowed. The easiest way to fix this is to make ScrollView
        simply ask the platform widget whether this is safe on platforms that
        are affected.

        It is not possible to write a layout test for this bug because it
        involves the back/forward cache.

        * platform/ScrollView.cpp:
        (WebCore::ScrollView::ScrollView):
        (WebCore::ScrollView::setCanBlitOnScroll):
        (WebCore::ScrollView::canBlitOnScroll):
        (WebCore::ScrollView::platformSetCanBlitOnScroll):
        (WebCore::ScrollView::platformCanBlitOnScroll):
        * platform/ScrollView.h:
        * platform/mac/ScrollViewMac.mm:
        (WebCore::ScrollView::platformSetCanBlitOnScroll):
        (WebCore::ScrollView::platformCanBlitOnScroll):
        * platform/wx/ScrollViewWx.cpp:
        (WebCore::ScrollView::platformSetCanBlitOnScroll):
        (WebCore::ScrollView::platformCanBlitOnScroll):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@39217 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/WebCore/ChangeLog b/WebCore/ChangeLog
index e77ea7d..62bfd82 100644 (file)
--- a/WebCore/ChangeLog
+++ b/WebCore/ChangeLog
@@ -1,3 +1,34 @@
+2008-12-11  Cameron Zwarich  <zwarich@apple.com>
+
+        Reviewed by Dave Hyatt.
+
+        Bug 21256: REGRESSION (r36906): horizontally repeating image leaves ghosts when vertical scrolling
+        <https://bugs.webkit.org/show_bug.cgi?id=21256>
+        <rdar://problem/6362978>
+
+        The ScrollView refactoring in r36906 caused the ScrollView and the
+        platform widget to disagree about whether optimizing scrolling via
+        blitting is allowed. The easiest way to fix this is to make ScrollView
+        simply ask the platform widget whether this is safe on platforms that
+        are affected.
+
+        It is not possible to write a layout test for this bug because it
+        involves the back/forward cache.
+
+        * platform/ScrollView.cpp:
+        (WebCore::ScrollView::ScrollView):
+        (WebCore::ScrollView::setCanBlitOnScroll):
+        (WebCore::ScrollView::canBlitOnScroll):
+        (WebCore::ScrollView::platformSetCanBlitOnScroll):
+        (WebCore::ScrollView::platformCanBlitOnScroll):
+        * platform/ScrollView.h:
+        * platform/mac/ScrollViewMac.mm:
+        (WebCore::ScrollView::platformSetCanBlitOnScroll):
+        (WebCore::ScrollView::platformCanBlitOnScroll):
+        * platform/wx/ScrollViewWx.cpp:
+        (WebCore::ScrollView::platformSetCanBlitOnScroll):
+        (WebCore::ScrollView::platformCanBlitOnScroll):
+
 2008-12-11  Brent Fulgham  <bfulgham@gmail.com>
 
         Reviewed by Adam Roben.

diff --git a/WebCore/platform/ScrollView.cpp b/WebCore/platform/ScrollView.cpp
index 97ce04e..f2d1e55 100644 (file)
--- a/WebCore/platform/ScrollView.cpp
+++ b/WebCore/platform/ScrollView.cpp
@@ -50,7 +50,7 @@ ScrollView::ScrollView()
 {
     platformInit();
     if (platformWidget())
-        platformSetCanBlitOnScroll();
+        platformSetCanBlitOnScroll(true);
 }
 
 ScrollView::~ScrollView()
@@ -147,11 +147,20 @@ void ScrollView::setCanHaveScrollbars(bool canScroll)
 
 void ScrollView::setCanBlitOnScroll(bool b)
 {
-    if (m_canBlitOnScroll == b)
+    if (platformWidget()) {
+        platformSetCanBlitOnScroll(b);
         return;
+    }
+
     m_canBlitOnScroll = b;
+}
+
+bool ScrollView::canBlitOnScroll() const
+{
     if (platformWidget())
-        platformSetCanBlitOnScroll();
+        return platformCanBlitOnScroll();
+
+    return m_canBlitOnScroll;
 }
 
 IntRect ScrollView::visibleContentRect(bool includeScrollbars) const
@@ -777,10 +786,6 @@ void ScrollView::platformRemoveChild(Widget*)
 #endif
 
 #if !PLATFORM(MAC)
-void ScrollView::platformSetCanBlitOnScroll()
-{
-}
-
 void ScrollView::platformSetScrollbarsSuppressed(bool repaintOnUnsuppress)
 {
 }
@@ -795,6 +800,15 @@ void ScrollView::platformScrollbarModes(ScrollbarMode& horizontal, ScrollbarMode
 {
 }
 
+void ScrollView::platformSetCanBlitOnScroll(bool)
+{
+}
+
+bool ScrollView::platformCanBlitOnScroll() const
+{
+    return false;
+}
+
 IntRect ScrollView::platformVisibleContentRect(bool) const
 {
     return IntRect();

diff --git a/WebCore/platform/ScrollView.h b/WebCore/platform/ScrollView.h
index 6f97e9c..b2fa582 100644 (file)
--- a/WebCore/platform/ScrollView.h
+++ b/WebCore/platform/ScrollView.h
@@ -105,7 +105,7 @@ public:
     // Whether or not a scroll view will blit visible contents when it is scrolled.  Blitting is disabled in situations
     // where it would cause rendering glitches (such as with fixed backgrounds or when the view is partially transparent).
     void setCanBlitOnScroll(bool);
-    bool canBlitOnScroll() const { return m_canBlitOnScroll; }
+    bool canBlitOnScroll() const;
 
     // The visible content rect has a location that is the scrolled offset of the document. The width and height are the viewport width
     // and height.  By default the scrollbars themselves are excluded from this rectangle, but an optional boolean argument allows them to be
@@ -232,7 +232,11 @@ private:
     bool m_prohibitsScrolling;
 
     HashSet<Widget*> m_children;
+
+    // This bool is unused on Mac OS because we directly ask the platform widget
+    // whether it is safe to blit on scroll.
     bool m_canBlitOnScroll;
+
     IntSize m_scrollOffset; // FIXME: Would rather store this as a position, but we will wait to make this change until more code is shared.
     IntSize m_contentsSize;
 
@@ -256,7 +260,8 @@ private:
     void platformRemoveChild(Widget*);
     void platformSetScrollbarModes();
     void platformScrollbarModes(ScrollbarMode& horizontal, ScrollbarMode& vertical) const;
-    void platformSetCanBlitOnScroll();
+    void platformSetCanBlitOnScroll(bool);
+    bool platformCanBlitOnScroll() const;
     IntRect platformVisibleContentRect(bool includeScrollbars) const;
     IntSize platformContentsSize() const;
     void platformSetContentsSize();

diff --git a/WebCore/platform/mac/ScrollViewMac.mm b/WebCore/platform/mac/ScrollViewMac.mm
index 6d477e2..d9f4f17 100644 (file)
--- a/WebCore/platform/mac/ScrollViewMac.mm
+++ b/WebCore/platform/mac/ScrollViewMac.mm
@@ -92,14 +92,19 @@ void ScrollView::platformScrollbarModes(ScrollbarMode& horizontal, ScrollbarMode
     [scrollView() scrollingModes:&horizontal vertical:&vertical];
     END_BLOCK_OBJC_EXCEPTIONS;
 }
-    
-void ScrollView::platformSetCanBlitOnScroll()
+
+void ScrollView::platformSetCanBlitOnScroll(bool canBlitOnScroll)
 {
     BEGIN_BLOCK_OBJC_EXCEPTIONS;
-    [[scrollView() contentView] setCopiesOnScroll:canBlitOnScroll()];
+    [[scrollView() contentView] setCopiesOnScroll:canBlitOnScroll];
     END_BLOCK_OBJC_EXCEPTIONS;
 }
 
+bool ScrollView::platformCanBlitOnScroll() const
+{
+    return [[scrollView() contentView] copiesOnScroll];
+}
+
 IntRect ScrollView::platformVisibleContentRect(bool includeScrollbars) const
 {
     BEGIN_BLOCK_OBJC_EXCEPTIONS; 

diff --git a/WebCore/platform/wx/ScrollViewWx.cpp b/WebCore/platform/wx/ScrollViewWx.cpp
index 3822cba..254ac9f 100644 (file)
--- a/WebCore/platform/wx/ScrollViewWx.cpp
+++ b/WebCore/platform/wx/ScrollViewWx.cpp
@@ -306,6 +306,16 @@ void ScrollView::platformScrollbarModes(ScrollbarMode& horizontal, ScrollbarMode
     vertical = m_data->vScrollbarMode;
 }
 
+void ScrollView::platformSetCanBlitOnScroll(bool canBlitOnScroll)
+{
+    m_canBlitOnScroll = canBlitOnScroll;
+}
+
+bool ScrollView::platformCanBlitOnScroll() const
+{
+    return m_canBlitOnScroll;
+}
+
 // used for subframes support
 void ScrollView::platformAddChild(Widget* widget)
 {