First pass at removing position:fixed.

sky/engine/core/rendering/RenderGeometryMap.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 20 matching lines @@
 #include "core/rendering/RenderView.h"
 #include "platform/geometry/TransformState.h"
 #include "wtf/TemporaryChange.h"
 
 namespace blink {
 
 RenderGeometryMap::RenderGeometryMap(MapCoordinatesFlags flags)
     : m_insertionPosition(kNotFound)
     , m_nonUniformStepsCount(0)
     , m_transformedStepsCount(0)
-    , m_fixedStepsCount(0)
     , m_mapCoordinatesFlags(flags)
 {
 }
 
 RenderGeometryMap::~RenderGeometryMap()
 {
 }
 
 void RenderGeometryMap::mapToContainer(TransformState& transformState, const RenderLayerModelObject* container) const
 {
     // If the mapping includes something like columns, we have to go via renderers.
     if (hasNonUniformStep()) {
         m_mapping.last().m_renderer->mapLocalToContainer(container, transformState, ApplyContainerFlip | m_mapCoordinatesFlags);
         transformState.flatten();
         return;
     }
 
-    bool inFixed = false;
 #if ENABLE(ASSERT)
     bool foundContainer = !container || (m_mapping.size() && m_mapping[0].m_renderer == container);
 #endif
 
     for (int i = m_mapping.size() - 1; i >= 0; --i) {
         const RenderGeometryMapStep& currentStep = m_mapping[i];
 
         // If container is the root RenderView (step 0) we want to apply its fixed position offset.
         if (i > 0 && currentStep.m_renderer == container) {
 #if ENABLE(ASSERT)
             foundContainer = true;
 #endif
             break;
         }
 
-        // If this box has a transform, it acts as a fixed position container
-        // for fixed descendants, which prevents the propagation of 'fixed'
-        // unless the layer itself is also fixed position.
-        if (i && currentStep.m_hasTransform && !currentStep.m_isFixedPosition)
-            inFixed = false;
-        else if (currentStep.m_isFixedPosition)
-            inFixed = true;
-
         ASSERT(!i == isTopmostRenderView(currentStep.m_renderer));
 
         if (!i) {
             // A null container indicates mapping through the root RenderView, so including its transform (the page scale).
             if (!container && currentStep.m_transform)
                 transformState.applyTransform(*currentStep.m_transform.get());
         } else {
             TransformState::TransformAccumulation accumulate = currentStep.m_accumulatingTransform ? TransformState::AccumulateTransform : TransformState::FlattenTransform;
             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_renderer->isRenderView());
-            transformState.move(currentStep.m_offsetForFixedPosition);
-        }
     }
 
     ASSERT(foundContainer);
     transformState.flatten();
 }
 
 FloatPoint RenderGeometryMap::mapToContainer(const FloatPoint& p, const RenderLayerModelObject* container) const
 {
     FloatPoint result;
 
-    if (!hasFixedPositionStep() && !hasTransformStep() && !hasNonUniformStep() && (!container || (m_mapping.size() && container == m_mapping[0].m_renderer)))
+    if (!hasTransformStep() && !hasNonUniformStep() && (!container || (m_mapping.size() && container == m_mapping[0].m_renderer)))
         result = p + m_accumulatedOffset;
     else {
         TransformState transformState(TransformState::ApplyTransformDirection, p);
         mapToContainer(transformState, container);
         result = transformState.lastPlanarPoint();
     }
 
 #if ENABLE(ASSERT)
     if (m_mapping.size() > 0) {
         const RenderObject* lastRenderer = m_mapping.last().m_renderer;
@@ skipping 24 matching lines @@
             fprintf(stderr, " hasTransform");
         fprintf(stderr, "\n");
     }
 }
 #endif
 
 FloatQuad RenderGeometryMap::mapToContainer(const FloatRect& rect, const RenderLayerModelObject* container) const
 {
     FloatRect result;
 
-    if (!hasFixedPositionStep() && !hasTransformStep() && !hasNonUniformStep() && (!container || (m_mapping.size() && container == m_mapping[0].m_renderer))) {
+    if (!hasTransformStep() && !hasNonUniformStep() && (!container || (m_mapping.size() && container == m_mapping[0].m_renderer))) {
         result = rect;
         result.move(m_accumulatedOffset);
     } else {
         TransformState transformState(TransformState::ApplyTransformDirection, rect.center(), rect);
         mapToContainer(transformState, container);
         result = transformState.lastPlanarQuad().boundingBox();
     }
 
 #if ENABLE(ASSERT)
     if (m_mapping.size() > 0) {
@@ skipping 21 matching lines @@
         renderer = renderer->pushMappingToContainer(ancestorRenderer, *this);
     } while (renderer && renderer != ancestorRenderer);
 
     ASSERT(m_mapping.isEmpty() || isTopmostRenderView(m_mapping[0].m_renderer));
 }
 
 static bool canMapBetweenRenderers(const RenderObject* renderer, const RenderObject* ancestor)
 {
     for (const RenderObject* current = renderer; ; current = current->parent()) {
         const RenderStyle* style = current->style();
-        if (style->position() == FixedPosition || style->isFlippedBlocksWritingMode())
+        if (style->isFlippedBlocksWritingMode())
             return false;
 
         if (current->hasTransform())
             return false;
 
         if (current == ancestor)
             break;
     }
 
     return true;
@@ skipping 17 matching lines @@
         layer->convertToLayerCoords(ancestorLayer, layerOffset);
 
         // The RenderView must be pushed first.
         if (!m_mapping.size()) {
             ASSERT(ancestorLayer->renderer()->isRenderView());
             pushMappingsToAncestor(ancestorLayer->renderer(), 0);
         }
 
         TemporaryChange<size_t> positionChange(m_insertionPosition, m_mapping.size());
         bool accumulatingTransform = layer->renderer()->style()->preserves3D() || ancestorLayer->renderer()->style()->preserves3D();
-        push(renderer, toLayoutSize(layerOffset), accumulatingTransform, /*isNonUniform*/ false, /*isFixedPosition*/ false, /*hasTransform*/ false);
+        push(renderer, toLayoutSize(layerOffset), accumulatingTransform, /*isNonUniform*/ false, /*hasTransform*/ false);
         return;
     }
     const RenderLayerModelObject* ancestorRenderer = ancestorLayer ? ancestorLayer->renderer() : 0;
     pushMappingsToAncestor(renderer, ancestorRenderer);
 }
 
-void RenderGeometryMap::push(const RenderObject* renderer, const LayoutSize& offsetFromContainer, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition)
+void RenderGeometryMap::push(const RenderObject* renderer, const LayoutSize& offsetFromContainer, bool accumulatingTransform, bool isNonUniform, bool hasTransform)
 {
 //    fprintf(stderr, "RenderGeometryMap::push %p %d,%d isNonUniform=%d\n", renderer, offsetFromContainer.width().toInt(), offsetFromContainer.height().toInt(), isNonUniform);
 
     ASSERT(m_insertionPosition != kNotFound);
     ASSERT(!renderer->isRenderView() || !m_insertionPosition || m_mapCoordinatesFlags & TraverseDocumentBoundaries);
-    ASSERT(offsetForFixedPosition.isZero() || renderer->isRenderView());
 
-    m_mapping.insert(m_insertionPosition, RenderGeometryMapStep(renderer, accumulatingTransform, isNonUniform, isFixedPosition, hasTransform));
+    m_mapping.insert(m_insertionPosition, RenderGeometryMapStep(renderer, accumulatingTransform, isNonUniform, hasTransform));
 
     RenderGeometryMapStep& step = m_mapping[m_insertionPosition];
     step.m_offset = offsetFromContainer;
-    step.m_offsetForFixedPosition = offsetForFixedPosition;
 
     stepInserted(step);
 }
 
-void RenderGeometryMap::push(const RenderObject* renderer, const TransformationMatrix& t, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform, LayoutSize offsetForFixedPosition)
+void RenderGeometryMap::push(const RenderObject* renderer, const TransformationMatrix& t, bool accumulatingTransform, bool isNonUniform, bool hasTransform)
 {
     ASSERT(m_insertionPosition != kNotFound);
     ASSERT(!renderer->isRenderView() || !m_insertionPosition || m_mapCoordinatesFlags & TraverseDocumentBoundaries);
-    ASSERT(offsetForFixedPosition.isZero() || renderer->isRenderView());
 
-    m_mapping.insert(m_insertionPosition, RenderGeometryMapStep(renderer, accumulatingTransform, isNonUniform, isFixedPosition, hasTransform));
+    m_mapping.insert(m_insertionPosition, RenderGeometryMapStep(renderer, accumulatingTransform, isNonUniform, hasTransform));
 
     RenderGeometryMapStep& step = m_mapping[m_insertionPosition];
-    step.m_offsetForFixedPosition = offsetForFixedPosition;
 
     if (!t.isIntegerTranslation())
         step.m_transform = adoptPtr(new TransformationMatrix(t));
     else
         step.m_offset = LayoutSize(t.e(), t.f());
 
     stepInserted(step);
 }
 
 void RenderGeometryMap::popMappingsToAncestor(const RenderLayerModelObject* ancestorRenderer)
@@ skipping 14 matching lines @@
 
 void RenderGeometryMap::stepInserted(const RenderGeometryMapStep& step)
 {
     m_accumulatedOffset += step.m_offset;
 
     if (step.m_isNonUniform)
         ++m_nonUniformStepsCount;
 
     if (step.m_transform)
         ++m_transformedStepsCount;
-
-    if (step.m_isFixedPosition)
-        ++m_fixedStepsCount;
 }
 
 void RenderGeometryMap::stepRemoved(const RenderGeometryMapStep& step)
 {
     m_accumulatedOffset -= step.m_offset;
 
     if (step.m_isNonUniform) {
         ASSERT(m_nonUniformStepsCount);
         --m_nonUniformStepsCount;
     }
 
     if (step.m_transform) {
         ASSERT(m_transformedStepsCount);
         --m_transformedStepsCount;
     }
-
-    if (step.m_isFixedPosition) {
-        ASSERT(m_fixedStepsCount);
-        --m_fixedStepsCount;
-    }
 }
 
 #if ENABLE(ASSERT)
 bool RenderGeometryMap::isTopmostRenderView(const RenderObject* renderer) const
 {
     if (!renderer->isRenderView())
         return false;
 
     // If we're not working with multiple RenderViews, then any view is considered
     // "topmost" (to preserve original behavior).
     return !(m_mapCoordinatesFlags & TraverseDocumentBoundaries);
 }
 #endif
 
 } // namespace blink