Get rid of clampScrollOffset and make maximumScrollPosition sane.

Source/core/paint/DeprecatedPaintLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 471 matching lines @@
     return DoublePoint(m_scrollOffset);
 }
 
 IntPoint DeprecatedPaintLayerScrollableArea::minimumScrollPosition() const
 {
     return -scrollOrigin();
 }
 
 IntPoint DeprecatedPaintLayerScrollableArea::maximumScrollPosition() const
 {
-    if (!box().hasOverflowClip())
-        return -scrollOrigin();
-    return -scrollOrigin() + IntPoint(pixelSnappedScrollWidth(), pixelSnappedScrollHeight()) - enclosingIntRect(box().clientBoxRect()).size();
+    IntSize contentSize;
+    IntSize visibleSize;
+    if (layer()->isRootLayer()) {
+        FrameView* frameView = box().frameView();
+        contentSize = frameView->contentsSize();
+        visibleSize = frameView->visibleContentSize(ExcludeScrollbars) + frameView->topControlsSize();
+    } else if (box().hasOverflowClip()) {
+        contentSize = IntSize(pixelSnappedScrollWidth(), pixelSnappedScrollHeight());
+        visibleSize = enclosingIntRect(box().clientBoxRect()).size();
+    }
+    return -scrollOrigin() + (contentSize - visibleSize);
 }
 
 IntRect DeprecatedPaintLayerScrollableArea::visibleContentRect(IncludeScrollbarsInRect scrollbarInclusion) const
 {
     int verticalScrollbarWidth = 0;
     int horizontalScrollbarHeight = 0;
     if (scrollbarInclusion == IncludeScrollbars) {
         verticalScrollbarWidth = (verticalScrollbar() && !verticalScrollbar()->isOverlayScrollbar()) ? verticalScrollbar()->width() : 0;
         horizontalScrollbarHeight = (horizontalScrollbar() && !horizontalScrollbar()->isOverlayScrollbar()) ? horizontalScrollbar()->height() : 0;
     }
@@ skipping 130 matching lines @@
 void DeprecatedPaintLayerScrollableArea::computeScrollDimensions()
 {
     m_overflowRect = box().layoutOverflowRect();
     box().flipForWritingMode(m_overflowRect);
 
     int scrollableLeftOverflow = m_overflowRect.x() - box().borderLeft() - (box().style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft() ? box().verticalScrollbarWidth() : 0);
     int scrollableTopOverflow = m_overflowRect.y() - box().borderTop();
     setScrollOrigin(IntPoint(-scrollableLeftOverflow, -scrollableTopOverflow));
 }
 
-void DeprecatedPaintLayerScrollableArea::scrollToOffset(const DoubleSize& scrollOffset, ScrollOffsetClamping clamp, ScrollBehavior scrollBehavior)
+void DeprecatedPaintLayerScrollableArea::scrollToPosition(const DoublePoint& scrollPosition, ScrollOffsetClamping clamp, ScrollBehavior scrollBehavior)
 {
     cancelProgrammaticScrollAnimation();
-    DoubleSize newScrollOffset = clamp == ScrollOffsetClamped ? clampScrollOffset(scrollOffset) : scrollOffset;
-    if (newScrollOffset != adjustedScrollOffset()) {
-        DoublePoint origin(scrollOrigin());
-        ScrollableArea::setScrollPosition(-origin + newScrollOffset, ProgrammaticScroll, scrollBehavior);
-    }
+
+    DoublePoint newScrollPosition = clamp == ScrollOffsetClamped ? clampScrollPosition(scrollPosition) : scrollPosition;
+    if (newScrollPosition != scrollPositionDouble())
+        ScrollableArea::setScrollPosition(newScrollPosition, ProgrammaticScroll, scrollBehavior);
 }
 
 void DeprecatedPaintLayerScrollableArea::updateScrollDimensions(DoubleSize& scrollOffset, bool& autoHorizontalScrollBarChanged, bool& autoVerticalScrollBarChanged)
 {
     ASSERT(box().hasOverflowClip());
 
     if (needsScrollbarReconstruction()) {
         if (m_hBar)
             destroyScrollbar(HorizontalScrollbar);
         if (m_vBar)
@@ skipping 21 matching lines @@
             setHasVerticalScrollbar(box().style()->overflowY() == OSCROLL ? true : hasVerticalOverflow);
     }
 }
 
 void DeprecatedPaintLayerScrollableArea::finalizeScrollDimensions(const DoubleSize& originalScrollOffset, bool autoHorizontalScrollBarChanged, bool autoVerticalScrollBarChanged)
 {
     ASSERT(box().hasOverflowClip());
 
     // Layout may cause us to be at an invalid scroll position. In this case we need
     // to pull our scroll offsets back to the max (or push them up to the min).
-    DoubleSize clampedScrollOffset = clampScrollOffset(adjustedScrollOffset());
-    if (clampedScrollOffset != adjustedScrollOffset())
-        scrollToOffset(clampedScrollOffset);
+    DoublePoint clampedScrollPosition = clampScrollPosition(scrollPositionDouble());
+    if (clampedScrollPosition != scrollPositionDouble())
+        scrollToPosition(clampedScrollPosition);
 
     if (originalScrollOffset != adjustedScrollOffset()) {
         DoublePoint origin(scrollOrigin());
         scrollPositionChanged(-origin + adjustedScrollOffset(), ProgrammaticScroll);
     }
 
     bool hasHorizontalOverflow = this->hasHorizontalOverflow();
     bool hasVerticalOverflow = this->hasVerticalOverflow();
 
     {
@@ skipping 189 matching lines @@
     }
 
     bool hasHorizontalOverflow = this->hasHorizontalOverflow();
     bool hasVerticalOverflow = this->hasVerticalOverflow();
     bool autoHorizontalScrollBarChanged = box().hasAutoHorizontalScrollbar() && (hasHorizontalScrollbar() != hasHorizontalOverflow);
     bool autoVerticalScrollBarChanged = box().hasAutoVerticalScrollbar() && (hasVerticalScrollbar() != hasVerticalOverflow);
     if (autoHorizontalScrollBarChanged || autoVerticalScrollBarChanged)
         box().setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::Unknown);
 }
 
-DoubleSize DeprecatedPaintLayerScrollableArea::clampScrollOffset(const DoubleSize& scrollOffset) const
-{
-    int maxX = scrollWidth() - box().pixelSnappedClientWidth();
-    int maxY = scrollHeight() - box().pixelSnappedClientHeight();
-
-    double x = std::max(std::min(scrollOffset.width(), static_cast<double>(maxX)), 0.0);
-    double y = std::max(std::min(scrollOffset.height(), static_cast<double>(maxY)), 0.0);
-    return DoubleSize(x, y);
-}
-
 IntRect DeprecatedPaintLayerScrollableArea::rectForHorizontalScrollbar(const IntRect& borderBoxRect) const
 {
     if (!m_hBar)
         return IntRect();
 
     const IntRect& scrollCorner = scrollCornerRect();
 
     return IntRect(horizontalScrollbarStart(borderBoxRect.x()),
         borderBoxRect.maxY() - box().borderBottom() - m_hBar->height(),
         borderBoxRect.width() - (box().borderLeft() + box().borderRight()) - scrollCorner.width(),
@@ skipping 469 matching lines @@
     // FIXME (Radar 4118564): We should also autoscroll the window as necessary to keep the point under the cursor in view.
 }
 
 LayoutRect DeprecatedPaintLayerScrollableArea::scrollIntoView(const LayoutRect& rect, const ScrollAlignment& alignX, const ScrollAlignment& alignY)
 {
     LayoutRect localExposeRect(box().absoluteToLocalQuad(FloatQuad(FloatRect(rect)), UseTransforms).boundingBox());
     localExposeRect.move(-box().borderLeft(), -box().borderTop());
     LayoutRect layerBounds(0, 0, box().clientWidth(), box().clientHeight());
     LayoutRect r = ScrollAlignment::getRectToExpose(layerBounds, localExposeRect, alignX, alignY);
 
-    DoubleSize clampedScrollOffset = clampScrollOffset(adjustedScrollOffset() + roundedIntSize(r.location()));
-    if (clampedScrollOffset == adjustedScrollOffset())
+    DoublePoint clampedScrollPosition = clampScrollPosition(scrollPositionDouble() + roundedIntSize(r.location()));
+    if (clampedScrollPosition == scrollPositionDouble())
         return rect;
 
     DoubleSize oldScrollOffset = adjustedScrollOffset();
-    scrollToOffset(clampedScrollOffset);
+    scrollToPosition(clampedScrollPosition);
     DoubleSize scrollOffsetDifference = adjustedScrollOffset() - oldScrollOffset;
     localExposeRect.move(-LayoutSize(scrollOffsetDifference));
     return LayoutRect(box().localToAbsoluteQuad(FloatQuad(FloatRect(localExposeRect)), UseTransforms).boundingBox());
 }
 
 void DeprecatedPaintLayerScrollableArea::updateScrollableAreaSet(bool hasOverflow)
 {
     LocalFrame* frame = box().frame();
     if (!frame)
         return;
@@ skipping 81 matching lines @@
         return false;
 
     LocalFrame* frame = box().frame();
     if (!frame || !frame->isMainFrame() || !frame->settings())
         return false;
 
     return frame->settings()->viewportMetaEnabled();
 }
 
 } // namespace blink