Adapt and reland old position sticky implementation

third_party/WebKit/Source/core/layout/LayoutGeometryMap.cpp

 /*
  * Copyright (C) 2012 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 87 matching lines @@
             if (currentStep.m_transform)
                 transformState.applyTransform(*currentStep.m_transform.get(), accumulate);
             else
                 transformState.move(currentStep.m_offset.width(), currentStep.m_offset.height(), accumulate);
         }
 
         if (inFixed && !currentStep.m_offsetForFixedPosition.isZero()) {
             ASSERT(currentStep.m_layoutObject->isLayoutView());
             transformState.move(currentStep.m_offsetForFixedPosition);
         }
+        if (!currentStep.m_offsetForStickyPosition.isZero()) {
+            ASSERT(currentStep.m_layoutObject->style()->position() == StickyPosition);
+            transformState.move(currentStep.m_offsetForStickyPosition);
+        }
     }
 
     ASSERT(foundAncestor);
     transformState.flatten();
 }
 
 #ifndef NDEBUG
 // Handy function to call from gdb while debugging mismatched point/rect errors.
 void LayoutGeometryMap::dumpSteps() const
 {
@@ skipping 93 matching lines @@
 
         TemporaryChange<size_t> positionChange(m_insertionPosition, m_mapping.size());
         bool accumulatingTransform = layer->layoutObject()->style()->preserves3D() || ancestorLayer->layoutObject()->style()->preserves3D();
         push(layoutObject, toLayoutSize(layerOffset), accumulatingTransform, /*isNonUniform*/ false, /*isFixedPosition*/ false, /*hasTransform*/ false);
         return;
     }
     const LayoutBoxModelObject* ancestorLayoutObject = ancestorLayer ? ancestorLayer->layoutObject() : 0;
     pushMappingsToAncestor(layoutObject, ancestorLayoutObject);
 }
 
-void LayoutGeometryMap::push(const LayoutObject* layoutObject, const LayoutSize& offsetFromContainer, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition)
+void LayoutGeometryMap::push(const LayoutObject* layoutObject, const LayoutSize& offsetFromContainer, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition, LayoutSize offsetForStickyPosition)
 {
     LAYOUT_GEOMETRY_MAP_LOG("LayoutGeometryMap::push %p %d,%d isNonUniform=%d\n", layoutObject, offsetFromContainer.width().toInt(), offsetFromContainer.height().toInt(), isNonUniform);
 
     ASSERT(m_insertionPosition != kNotFound);
     ASSERT(!layoutObject->isLayoutView() || !m_insertionPosition || m_mapCoordinatesFlags & TraverseDocumentBoundaries);
     ASSERT(offsetForFixedPosition.isZero() || layoutObject->isLayoutView());
+    ASSERT(offsetForStickyPosition.isZero() || layoutObject->style()->position() == StickyPosition);
 
     m_mapping.insert(m_insertionPosition, LayoutGeometryMapStep(layoutObject, accumulatingTransform, isNonUniform, isFixedPosition, hasTransform));
 
     LayoutGeometryMapStep& step = m_mapping[m_insertionPosition];
     step.m_offset = offsetFromContainer;
     step.m_offsetForFixedPosition = offsetForFixedPosition;
+    step.m_offsetForStickyPosition = offsetForStickyPosition;
 
     stepInserted(step);
 }
 
-void LayoutGeometryMap::push(const LayoutObject* layoutObject, const TransformationMatrix& t, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition)
+void LayoutGeometryMap::push(const LayoutObject* layoutObject, const TransformationMatrix& t, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition, LayoutSize offsetForStickyPosition)
 {
     ASSERT(m_insertionPosition != kNotFound);
     ASSERT(!layoutObject->isLayoutView() || !m_insertionPosition || m_mapCoordinatesFlags & TraverseDocumentBoundaries);
     ASSERT(offsetForFixedPosition.isZero() || layoutObject->isLayoutView());
+    ASSERT(offsetForStickyPosition.isZero() || layoutObject->style()->position() == StickyPosition);
 
     m_mapping.insert(m_insertionPosition, LayoutGeometryMapStep(layoutObject, accumulatingTransform, isNonUniform, isFixedPosition, hasTransform));
 
     LayoutGeometryMapStep& step = m_mapping[m_insertionPosition];
     step.m_offsetForFixedPosition = offsetForFixedPosition;
+    step.m_offsetForStickyPosition = offsetForStickyPosition;
 
     if (!t.isIntegerTranslation())
         step.m_transform = adoptPtr(new TransformationMatrix(t));
     else
         step.m_offset = LayoutSize(t.e(), t.f());
 
     stepInserted(step);
 }
 
 void LayoutGeometryMap::popMappingsToAncestor(const LayoutBoxModelObject* ancestorLayoutObject)
@@ skipping 55 matching lines @@
     // If we're not working with multiple LayoutViews, then any view is considered
     // "topmost" (to preserve original behavior).
     if (!(m_mapCoordinatesFlags & TraverseDocumentBoundaries))
         return true;
 
     return layoutObject->frame()->isMainFrame();
 }
 #endif
 
 } // namespace blink