Make it possibe to lock the fixedLayoutSize

Source/core/platform/ScrollView.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 32 matching lines @@
     , m_verticalScrollbarMode(ScrollbarAuto)
     , m_horizontalScrollbarLock(false)
     , m_verticalScrollbarLock(false)
     , m_canBlitOnScroll(true)
     , m_scrollbarsAvoidingResizer(0)
     , m_scrollbarsSuppressed(false)
     , m_inUpdateScrollbars(false)
     , m_updateScrollbarsPass(0)
     , m_drawPanScrollIcon(false)
     , m_useFixedLayout(false)
+    , m_fixedLayoutSizeLock(false)
     , m_paintsEntireContents(false)
     , m_clipsRepaints(true)
 {
 }
 
 ScrollView::~ScrollView()
 {
 }
 
 void ScrollView::addChild(PassRefPtr<Widget> prpChild)
@@ skipping 135 matching lines @@
             horizontalScrollbarHeight = !horizontalBar->isOverlayScrollbar() ? horizontalBar->height() : 0;
     }
 
     return IntSize(max(0, width() - verticalScrollbarWidth),
                    max(0, height() - horizontalScrollbarHeight));
 }
 
 IntRect ScrollView::visibleContentRect(VisibleContentRectIncludesScrollbars scollbarInclusion) const
 {
     FloatSize visibleContentSize = unscaledVisibleContentSize(scollbarInclusion);
-    visibleContentSize.scale(1 / visibleContentScaleFactor());
+    if (!m_fixedLayoutSizeLock)
+        visibleContentSize.scale(1 / visibleContentScaleFactor());
     return IntRect(IntPoint(m_scrollOffset), expandedIntSize(visibleContentSize));
 }
 
 IntSize ScrollView::layoutSize(VisibleContentRectIncludesScrollbars scrollbarInclusion) const
 {
-    return m_fixedLayoutSize.isEmpty() || !m_useFixedLayout ? unscaledVisibleContentSize(scrollbarInclusion) : m_fixedLayoutSize;
+    return m_fixedLayoutSize.isZero() || !m_useFixedLayout ? unscaledVisibleContentSize(scrollbarInclusion) : m_fixedLayoutSize;
 }
 
 IntSize ScrollView::fixedLayoutSize() const
 {
     return m_fixedLayoutSize;
 }
 
 void ScrollView::setFixedLayoutSize(const IntSize& newSize)
 {
+    if (m_fixedLayoutSizeLock)
+        return;
     if (fixedLayoutSize() == newSize)
         return;
     m_fixedLayoutSize = newSize;
     updateScrollbars(scrollOffset());
     if (m_useFixedLayout)
         contentsResized();
 }
 
 bool ScrollView::useFixedLayout() const
 {
     return m_useFixedLayout;
 }
 
 void ScrollView::setUseFixedLayout(bool enable)
 {
     if (useFixedLayout() == enable)
         return;
     m_useFixedLayout = enable;
     updateScrollbars(scrollOffset());
     contentsResized();
 }
 
+void ScrollView::setFixedLayoutSizeLock(bool enable)
+{
+    m_fixedLayoutSizeLock = enable;
+}
+
+bool ScrollView::fixedLayoutSizeLock() const
+{
+    return m_fixedLayoutSizeLock;
+}
+
 IntSize ScrollView::contentsSize() const
 {
     return m_contentsSize;
 }
 
 void ScrollView::setContentsSize(const IntSize& newSize)
 {
     if (contentsSize() == newSize)
         return;
     m_contentsSize = newSize;
@@ skipping 931 matching lines @@
 int ScrollView::pageStep(ScrollbarOrientation orientation) const
 {
     int length = (orientation == HorizontalScrollbar) ? visibleWidth() : visibleHeight();
     int minPageStep = static_cast<float>(length) * minFractionToStepWhenPaging();
     int pageStep = std::max(minPageStep, length - maxOverlapBetweenPages());
 
     return std::max(pageStep, 1);
 }
 
 } // namespace WebCore