Source/WebCore/rendering/RenderGeometryMap.h

/*
 * 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
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include "FloatPoint.h"
#include "FloatQuad.h"
#include "LayoutSize.h"
#include "RenderObject.h"
#include "TransformationMatrix.h"
#include <memory>

namespace WebCore {

class RenderFragmentedFlow;
class RenderLayer;
class RenderLayerModelObject;
class RenderView;
class TransformState;

// Stores data about how to map from one renderer to its container.
struct RenderGeometryMapStep {
    RenderGeometryMapStep(const RenderGeometryMapStep& o)
        : m_renderer(o.m_renderer)
        , m_offset(o.m_offset)
        , m_accumulatingTransform(o.m_accumulatingTransform)
        , m_isNonUniform(o.m_isNonUniform)
        , m_isFixedPosition(o.m_isFixedPosition)
        , m_hasTransform(o.m_hasTransform)
    {
        ASSERT(!o.m_transform);
    }
    RenderGeometryMapStep(const RenderObject* renderer, bool accumulatingTransform, bool isNonUniform, bool isFixedPosition, bool hasTransform)
        : m_renderer(renderer)
        , m_accumulatingTransform(accumulatingTransform)
        , m_isNonUniform(isNonUniform)
        , m_isFixedPosition(isFixedPosition)
        , m_hasTransform(hasTransform)
    {
    }
    const RenderObject* m_renderer;
    LayoutSize m_offset;
    std::unique_ptr<TransformationMatrix> m_transform; // Includes offset if non-null.
    bool m_accumulatingTransform;
    bool m_isNonUniform; // Mapping depends on the input point, e.g. because of CSS columns.
    bool m_isFixedPosition;
    bool m_hasTransform;
};

// Can be used while walking the Renderer tree to cache data about offsets and transforms.
class RenderGeometryMap {
    WTF_MAKE_NONCOPYABLE(RenderGeometryMap);
public:
    explicit RenderGeometryMap(MapCoordinatesFlags = UseTransforms);
    ~RenderGeometryMap();

    MapCoordinatesFlags mapCoordinatesFlags() const { return m_mapCoordinatesFlags; }

    FloatPoint absolutePoint(const FloatPoint& p) const
    {
        return mapToContainer(p, nullptr);
    }

    FloatRect absoluteRect(const FloatRect& rect) const
    {
        return mapToContainer(rect, nullptr).boundingBox();
    }

    // Map to a container. Will assert that the container has been pushed onto this map.
    // A null container maps through the RenderView (including its scale transform, if any).
    // If the container is the RenderView, the scroll offset is applied, but not the scale.
    FloatPoint mapToContainer(const FloatPoint&, const RenderLayerModelObject*) const;
    FloatQuad mapToContainer(const FloatRect&, const RenderLayerModelObject*) const;
    
    // Called by code walking the renderer or layer trees.
    void pushMappingsToAncestor(const RenderLayer*, const RenderLayer* ancestorLayer, bool respectTransforms = true);
    void popMappingsToAncestor(const RenderLayer*);
    void pushMappingsToAncestor(const RenderObject*, const RenderLayerModelObject* ancestorRenderer);
    void popMappingsToAncestor(const RenderLayerModelObject*);
    
    // The following methods should only be called by renderers inside a call to pushMappingsToAncestor().

    // Push geometry info between this renderer and some ancestor. The ancestor must be its container() or some
    // stacking context between the renderer and its container.
    void push(const RenderObject*, const LayoutSize&, bool accumulatingTransform = false, bool isNonUniform = false, bool isFixedPosition = false, bool hasTransform = false);
    void push(const RenderObject*, const TransformationMatrix&, bool accumulatingTransform = false, bool isNonUniform = false, bool isFixedPosition = false, bool hasTransform = false);

    // RenderView gets special treatment, because it applies the scroll offset only for elements inside in fixed position.
    void pushView(const RenderView*, const LayoutSize& scrollOffset, const TransformationMatrix* = nullptr);
    void pushRenderFragmentedFlow(const RenderFragmentedFlow*);

private:
    void mapToContainer(TransformState&, const RenderLayerModelObject* container = nullptr) const;

    void stepInserted(const RenderGeometryMapStep&);
    void stepRemoved(const RenderGeometryMapStep&);
    
    bool hasNonUniformStep() const { return m_nonUniformStepsCount; }
    bool hasTransformStep() const { return m_transformedStepsCount; }
    bool hasFixedPositionStep() const { return m_fixedStepsCount; }

    typedef Vector<RenderGeometryMapStep, 32> RenderGeometryMapSteps;

    size_t m_insertionPosition;
    int m_nonUniformStepsCount;
    int m_transformedStepsCount;
    int m_fixedStepsCount;
    RenderGeometryMapSteps m_mapping;
    LayoutSize m_accumulatedOffset;
    MapCoordinatesFlags m_mapCoordinatesFlags;
#if ASSERT_ENABLED
    bool m_accumulatedOffsetMightBeSaturated { false };
#endif
};

} // namespace WebCore

namespace WTF {
// This is required for a struct with std::unique_ptr<>. We know RenderGeometryMapStep is simple enough that
// initializing to 0 and moving with memcpy (and then not destructing the original) will work.
template<> struct VectorTraits<WebCore::RenderGeometryMapStep> : SimpleClassVectorTraits { };
}