Adapt and reland old position sticky implementation

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef LayoutBoxModelObject_h
 #define LayoutBoxModelObject_h
 
 #include "core/CoreExport.h"
 #include "core/layout/LayoutObject.h"
+#include "core/page/scrolling/StickyPositionScrollingConstraints.h"
 #include "core/style/ShadowData.h"
 #include "platform/geometry/LayoutRect.h"
 
 namespace blink {
 
 class LineLayoutBoxModel;
 class PaintLayer;
 class PaintLayerScrollableArea;
 
 enum PaintLayerType {
@@ skipping 18 matching lines @@
 };
 
 enum ContentChangeType {
     ImageChanged,
     CanvasChanged,
     CanvasContextChanged
 };
 
 class InlineFlowBox;
 
+struct LayoutBoxModelObjectRareData {
+    WTF_MAKE_NONCOPYABLE(LayoutBoxModelObjectRareData);
+    USING_FAST_MALLOC(LayoutBoxModelObjectRareData);
+public:
+    LayoutBoxModelObjectRareData() {}
+
+    StickyPositionScrollingConstraints m_stickyPositionScrollingConstraints;
+};
+
 // This class is the base class for all CSS objects.
 //
 // All CSS objects follow the box model object. See THE BOX MODEL section in
 // LayoutBox for more information.
 //
 // This class actually doesn't have the box model but it exposes some common
 // functions or concepts that sub-classes can extend upon. For example, there
 // are accessors for margins, borders, paddings and borderBoundingBox().
 //
 // The reason for this partial implementation is that the 2 classes inheriting
@@ skipping 57 matching lines @@
 public:
     LayoutBoxModelObject(ContainerNode*);
     ~LayoutBoxModelObject() override;
 
     // This is the only way layers should ever be destroyed.
     void destroyLayer();
 
     LayoutSize relativePositionOffset() const;
     LayoutSize relativePositionLogicalOffset() const { return style()->isHorizontalWritingMode() ? relativePositionOffset() : relativePositionOffset().transposedSize(); }
 
+    // Populates StickyPositionConstraints, setting the sticky box rect, containing block rect and updating
+    // the constraint offsets according to the available space.
+    FloatRect computeStickyConstrainingRect(const PaintLayer* ancestorOverflowLayer) const;
+    void updateStickyPositionConstraints(PaintLayer* ancestorOverflowLayer) const;
+    LayoutSize stickyPositionOffset() const;
+
     LayoutSize offsetForInFlowPosition() const;
 
     // IE extensions. Used to calculate offsetWidth/Height.  Overridden by inlines (LayoutFlow)
     // to return the remaining width on a given line (and the height of a single line).
     virtual LayoutUnit offsetLeft() const;
     virtual LayoutUnit offsetTop() const;
     virtual LayoutUnit offsetWidth() const = 0;
     virtual LayoutUnit offsetHeight() const = 0;
 
     int pixelSnappedOffsetLeft() const { return roundToInt(offsetLeft()); }
@@ skipping 120 matching lines @@
 
     void contentChanged(ContentChangeType);
     bool hasAcceleratedCompositing() const;
 
     void computeLayerHitTestRects(LayerHitTestRects&) const override;
 
     // Returns true if the background is painted opaque in the given rect.
     // The query rect is given in local coordinate system.
     virtual bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect&) const { return false; }
 
+    void invalidateScrollAncestorConstraints();
+
     void invalidateTreeIfNeeded(PaintInvalidationState&) override;
 
     // Indicate that the contents of this layoutObject need to be repainted. Only has an effect if compositing is being used,
     void setBackingNeedsPaintInvalidationInRect(const LayoutRect&, PaintInvalidationReason) const; // r is in the coordinate space of this layout object
 
     void invalidateDisplayItemClientOnBacking(const DisplayItemClient&, PaintInvalidationReason) const;
 
     // http://www.w3.org/TR/css3-background/#body-background
     // <html> root element with no background steals background from its first <body> child.
     // The used background for such body element should be the initial value. (i.e. transparent)
@@ skipping 61 matching lines @@
 
     enum ScaleByEffectiveZoomOrNot { ScaleByEffectiveZoom, DoNotScaleByEffectiveZoom };
     LayoutSize calculateImageIntrinsicDimensions(StyleImage*, const LayoutSize& scaledPositioningAreaSize, ScaleByEffectiveZoomOrNot) const;
 
 private:
     void createLayer(PaintLayerType);
 
     LayoutUnit computedCSSPadding(const Length&) const;
     bool isBoxModelObject() const final { return true; }
 
+    LayoutBoxModelObjectRareData& ensureRareData()
+    {
+        if (!m_rareData)
+            m_rareData = adoptPtr(new LayoutBoxModelObjectRareData());
+        return *m_rareData.get();
+    }
+
     // The PaintLayer associated with this object.
     // |m_layer| can be nullptr depending on the return value of layerTypeRequired().
     OwnPtr<PaintLayer> m_layer;
+
+    OwnPtr<LayoutBoxModelObjectRareData> m_rareData;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBoxModelObject, isBoxModelObject());
 
 } // namespace blink
 
 #endif // LayoutBoxModelObject_h