*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/rendering/RenderLayerClipper.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 106 matching lines @@
 }
 
 LayoutRect RenderLayerClipper::childrenClipRect() const
 {
     // FIXME: border-radius not accounted for.
     // FIXME: Regions not accounted for.
     RenderView* renderView = m_renderer->view();
     RenderLayer* clippingRootLayer = m_renderer->layer()->clippingRootForPainting();
     LayoutRect layerBounds;
     ClipRect backgroundRect, foregroundRect, outlineRect;
-    ClipRectsContext clipRectsContext(clippingRootLayer, 0, TemporaryClipRects);
+    ClipRectsContext clipRectsContext(clippingRootLayer, TemporaryClipRects);
     // Need to use temporary clip rects, because the value of 'dontClipToOverflow' may be different from the painting path (<rdar://problem/11844909>).
     calculateRects(clipRectsContext, renderView->unscaledDocumentRect(), layerBounds, backgroundRect, foregroundRect, outlineRect);
     return clippingRootLayer->renderer()->localToAbsoluteQuad(FloatQuad(foregroundRect.rect())).enclosingBoundingBox();
 }
 
 LayoutRect RenderLayerClipper::selfClipRect() const
 {
     // FIXME: border-radius not accounted for.
     // FIXME: Regions not accounted for.
     RenderView* renderView = m_renderer->view();
     RenderLayer* clippingRootLayer = m_renderer->layer()->clippingRootForPainting();
     LayoutRect layerBounds;
     ClipRect backgroundRect, foregroundRect, outlineRect;
-    ClipRectsContext clipRectsContext(clippingRootLayer, 0, PaintingClipRects);
+    ClipRectsContext clipRectsContext(clippingRootLayer, PaintingClipRects);
     calculateRects(clipRectsContext, renderView->documentRect(), layerBounds, backgroundRect, foregroundRect, outlineRect);
     return clippingRootLayer->renderer()->localToAbsoluteQuad(FloatQuad(backgroundRect.rect())).enclosingBoundingBox();
 }
 
 LayoutRect RenderLayerClipper::localClipRect() const
 {
     // FIXME: border-radius not accounted for.
     // FIXME: Regions not accounted for.
     RenderLayer* clippingRootLayer = m_renderer->layer()->clippingRootForPainting();
     LayoutRect layerBounds;
     ClipRect backgroundRect, foregroundRect, outlineRect;
-    ClipRectsContext clipRectsContext(clippingRootLayer, 0, PaintingClipRects);
+    ClipRectsContext clipRectsContext(clippingRootLayer, PaintingClipRects);
     calculateRects(clipRectsContext, PaintInfo::infiniteRect(), layerBounds, backgroundRect, foregroundRect, outlineRect);
 
     LayoutRect clipRect = backgroundRect.rect();
     if (clipRect == PaintInfo::infiniteRect())
         return clipRect;
 
     LayoutPoint clippingRootOffset;
     m_renderer->layer()->convertToLayerCoords(clippingRootLayer, clippingRootOffset);
     clipRect.moveBy(-clippingRootOffset);
 
@@ skipping 17 matching lines @@
     if (offsetFromRoot)
         offset = *offsetFromRoot;
     else
         m_renderer->layer()->convertToLayerCoords(clipRectsContext.rootLayer, offset);
     layerBounds = LayoutRect(offset, m_renderer->layer()->size());
 
     // Update the clip rects that will be passed to child layers.
     if (m_renderer->hasOverflowClip()) {
         // This layer establishes a clip of some kind.
         if (m_renderer->layer() != clipRectsContext.rootLayer || clipRectsContext.respectOverflowClip == RespectOverflowClip) {
-            foregroundRect.intersect(toRenderBox(m_renderer)->overflowClipRect(offset, clipRectsContext.region, clipRectsContext.overlayScrollbarSizeRelevancy));
+            foregroundRect.intersect(toRenderBox(m_renderer)->overflowClipRect(offset, clipRectsContext.overlayScrollbarSizeRelevancy));
             if (m_renderer->style()->hasBorderRadius())
                 foregroundRect.setHasRadius(true);
         }
 
         // If we establish an overflow clip at all, then go ahead and make sure our background
         // rect is intersected with our layer's bounds including our visual overflow,
         // since any visual overflow like box-shadow or border-outset is not clipped by overflow:auto/hidden.
         if (toRenderBox(m_renderer)->hasVisualOverflow()) {
             // FIXME: Perhaps we should be propagating the borderbox as the clip rect for children, even though
             //        we may need to inflate our clip specifically for shadows or outsets.
             // FIXME: Does not do the right thing with CSS regions yet, since we don't yet factor in the
             // individual region boxes as overflow.
             LayoutRect layerBoundsWithVisualOverflow = toRenderBox(m_renderer)->visualOverflowRect();
             toRenderBox(m_renderer)->flipForWritingMode(layerBoundsWithVisualOverflow); // Layers are in physical coordinates, so the overflow has to be flipped.
             layerBoundsWithVisualOverflow.moveBy(offset);
             if (m_renderer->layer() != clipRectsContext.rootLayer || clipRectsContext.respectOverflowClip == RespectOverflowClip)
                 backgroundRect.intersect(layerBoundsWithVisualOverflow);
         } else {
-            // Shift the bounds to be for our region only.
-            LayoutRect bounds = toRenderBox(m_renderer)->borderBoxRectInRegion(clipRectsContext.region);
+            LayoutRect bounds = toRenderBox(m_renderer)->borderBoxRect();
             bounds.moveBy(offset);
             if (m_renderer->layer() != clipRectsContext.rootLayer || clipRectsContext.respectOverflowClip == RespectOverflowClip)
                 backgroundRect.intersect(bounds);
         }
     }
 
     // CSS clip (different than clipping due to overflow) can clip to any box, even if it falls outside of the border box.
     if (m_renderer->hasClip()) {
         // Clip applies to *us* as well, so go ahead and update the damageRect.
-        LayoutRect newPosClip = toRenderBox(m_renderer)->clipRect(offset, clipRectsContext.region);
+        LayoutRect newPosClip = toRenderBox(m_renderer)->clipRect(offset);
         backgroundRect.intersect(newPosClip);
         foregroundRect.intersect(newPosClip);
         outlineRect.intersect(newPosClip);
     }
 }
 
 void RenderLayerClipper::calculateClipRects(const ClipRectsContext& clipRectsContext, ClipRects& clipRects) const
 {
     if (!m_renderer->layer()->parent()) {
         // The root layer's clip rect is always infinite.
@@ skipping 42 matching lines @@
         // clipRects are needed in view space.
         LayoutPoint offset;
         offset = roundedLayoutPoint(m_renderer->localToContainerPoint(FloatPoint(), clipRectsContext.rootLayer->renderer()));
         RenderView* view = m_renderer->view();
         ASSERT(view);
         if (view && clipRects.fixed() && clipRectsContext.rootLayer->renderer() == view) {
             offset -= view->frameView()->scrollOffsetForFixedPosition();
         }
 
         if (m_renderer->hasOverflowClip()) {
-            ClipRect newOverflowClip = toRenderBox(m_renderer)->overflowClipRect(offset, clipRectsContext.region, clipRectsContext.overlayScrollbarSizeRelevancy);
+            ClipRect newOverflowClip = toRenderBox(m_renderer)->overflowClipRect(offset, clipRectsContext.overlayScrollbarSizeRelevancy);
             if (m_renderer->style()->hasBorderRadius())
                 newOverflowClip.setHasRadius(true);
             clipRects.setOverflowClipRect(intersection(newOverflowClip, clipRects.overflowClipRect()));
             if (m_renderer->isPositioned())
                 clipRects.setPosClipRect(intersection(newOverflowClip, clipRects.posClipRect()));
         }
         if (m_renderer->hasClip()) {
-            LayoutRect newPosClip = toRenderBox(m_renderer)->clipRect(offset, clipRectsContext.region);
+            LayoutRect newPosClip = toRenderBox(m_renderer)->clipRect(offset);
             clipRects.setPosClipRect(intersection(newPosClip, clipRects.posClipRect()));
             clipRects.setOverflowClipRect(intersection(newPosClip, clipRects.overflowClipRect()));
             clipRects.setFixedClipRect(intersection(newPosClip, clipRects.fixedClipRect()));
         }
     }
 }
 
 static inline ClipRect backgroundClipRectForPosition(const ClipRects& parentRects, EPosition position)
 {
     if (position == FixedPosition)
@@ skipping 40 matching lines @@
     if (clipRectsContext.clipRectsType == TemporaryClipRects) {
         parentClipper.calculateClipRects(clipRectsContext, clipRects);
         return;
     }
 
     parentClipper.updateClipRects(clipRectsContext);
     clipRects = *parentClipper.clipRects(clipRectsContext);
 }
 
 } // namespace WebCore