[cc] Rename all cc/ filenames to Chromium style

cc/layer_iterator.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
+
+#ifndef CCLayerIterator_h
+#define CCLayerIterator_h
+
+#include "CCLayerTreeHostCommon.h"
+
+#include "base/memory/ref_counted.h"
+
+namespace cc {
+
+// These classes provide means to iterate over the RenderSurface-Layer tree.
+
+// Example code follows, for a tree of LayerChromium/RenderSurfaceChromium objects. See below for details.
+//
+// void doStuffOnLayers(const std::vector<scoped_refptr<LayerChromium> >& renderSurfaceLayerList)
+// {
+//     typedef CCLayerIterator<LayerChromium, RenderSurfaceChromium, CCLayerIteratorActions::FrontToBack> CCLayerIteratorType;
+//
+//     CCLayerIteratorType end = CCLayerIteratorType::end(&renderSurfaceLayerList);
+//     for (CCLayerIteratorType it = CCLayerIteratorType::begin(&renderSurfaceLayerList); it != end; ++it) {
+//         // Only one of these will be true
+//         if (it.representsTargetRenderSurface())
+//             foo(*it); // *it is a layer representing a target RenderSurface
+//         if (it.representsContributingRenderSurface())
+//             bar(*it); // *it is a layer representing a RenderSurface that contributes to the layer's target RenderSurface
+//         if (it.representsItself())
+//             baz(*it); // *it is a layer representing itself, as it contributes to its own target RenderSurface
+//     }
+// }
+
+// A RenderSurface R may be referred to in one of two different contexts. One RenderSurface is "current" at any time, for
+// whatever operation is being performed. This current surface is referred to as a target surface. For example, when R is
+// being painted it would be the target surface. Once R has been painted, its contents may be included into another
+// surface S. While S is considered the target surface when it is being painted, R is called a contributing surface
+// in this context as it contributes to the content of the target surface S.
+//
+// The iterator's current position in the tree always points to some layer. The state of the iterator indicates the role of the
+// layer, and will be one of the following three states. A single layer L will appear in the iteration process in at least one,
+// and possibly all, of these states.
+// 1. Representing the target surface: The iterator in this state, pointing at layer L, indicates that the target RenderSurface
+// is now the surface owned by L. This will occur exactly once for each RenderSurface in the tree.
+// 2. Representing a contributing surface: The iterator in this state, pointing at layer L, refers to the RenderSurface owned
+// by L as a contributing surface, without changing the current target RenderSurface.
+// 3. Representing itself: The iterator in this state, pointing at layer L, refers to the layer itself, as a child of the
+// current target RenderSurface.
+//
+// The BackToFront iterator will return a layer representing the target surface before returning layers representing themselves
+// as children of the current target surface. Whereas the FrontToBack ordering will iterate over children layers of a surface
+// before the layer representing the surface as a target surface.
+//
+// To use the iterators:
+//
+// Create a stepping iterator and end iterator by calling CCLayerIterator::begin() and CCLayerIterator::end() and passing in the
+// list of layers owning target RenderSurfaces. Step through the tree by incrementing the stepping iterator while it is != to
+// the end iterator. At each step the iterator knows what the layer is representing, and you can query the iterator to decide
+// what actions to perform with the layer given what it represents.
+
+//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+// Non-templated constants
+struct CCLayerIteratorValue {
+    static const int InvalidTargetRenderSurfaceLayerIndex = -1;
+    // This must be -1 since the iterator action code assumes that this value can be
+    // reached by subtracting one from the position of the first layer in the current
+    // target surface's child layer list, which is 0.
+    static const int LayerIndexRepresentingTargetRenderSurface = -1;
+};
+
+// The position of a layer iterator that is independent of its many template types.
+template <typename LayerType>
+struct CCLayerIteratorPosition {
+    bool representsTargetRenderSurface;
+    bool representsContributingRenderSurface;
+    bool representsItself;
+    LayerType* targetRenderSurfaceLayer;
+    LayerType* currentLayer;
+};
+
+// An iterator class for walking over layers in the RenderSurface-Layer tree.
+template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename IteratorActionType>
+class CCLayerIterator {
+    typedef CCLayerIterator<LayerType, LayerList, RenderSurfaceType, IteratorActionType> CCLayerIteratorType;
+
+public:
+    CCLayerIterator() : m_renderSurfaceLayerList(0) { }
+
+    static CCLayerIteratorType begin(const LayerList* renderSurfaceLayerList) { return CCLayerIteratorType(renderSurfaceLayerList, true); }
+    static CCLayerIteratorType end(const LayerList* renderSurfaceLayerList) { return CCLayerIteratorType(renderSurfaceLayerList, false); }
+
+    CCLayerIteratorType& operator++() { m_actions.next(*this); return *this; }
+    bool operator==(const CCLayerIterator& other) const
+    {
+        return m_targetRenderSurfaceLayerIndex == other.m_targetRenderSurfaceLayerIndex
+            && m_currentLayerIndex == other.m_currentLayerIndex;
+    }
+    bool operator!=(const CCLayerIteratorType& other) const { return !(*this == other); }
+
+    LayerType* operator->() const { return currentLayer(); }
+    LayerType* operator*() const { return currentLayer(); }
+
+    bool representsTargetRenderSurface() const { return currentLayerRepresentsTargetRenderSurface(); }
+    bool representsContributingRenderSurface() const { return !representsTargetRenderSurface() && currentLayerRepresentsContributingRenderSurface(); }
+    bool representsItself() const { return !representsTargetRenderSurface() && !representsContributingRenderSurface(); }
+
+    LayerType* targetRenderSurfaceLayer() const { return getRawPtr((*m_renderSurfaceLayerList)[m_targetRenderSurfaceLayerIndex]); }
+
+    operator const CCLayerIteratorPosition<LayerType>() const
+    {
+        CCLayerIteratorPosition<LayerType> position;
+        position.representsTargetRenderSurface = representsTargetRenderSurface();
+        position.representsContributingRenderSurface = representsContributingRenderSurface();
+        position.representsItself = representsItself();
+        position.targetRenderSurfaceLayer = targetRenderSurfaceLayer();
+        position.currentLayer = currentLayer();
+        return position;
+    }
+
+private:
+    CCLayerIterator(const LayerList* renderSurfaceLayerList, bool start)
+        : m_renderSurfaceLayerList(renderSurfaceLayerList)
+        , m_targetRenderSurfaceLayerIndex(0)
+    {
+        for (size_t i = 0; i < renderSurfaceLayerList->size(); ++i) {
+            if (!(*renderSurfaceLayerList)[i]->renderSurface()) {
+                ASSERT_NOT_REACHED();
+                m_actions.end(*this);
+                return;
+            }
+        }
+
+        if (start && !renderSurfaceLayerList->empty())
+            m_actions.begin(*this);
+        else
+            m_actions.end(*this);
+    }
+
+    inline static LayerChromium* getRawPtr(const scoped_refptr<LayerChromium>& ptr) { return ptr.get(); }
+    inline static CCLayerImpl* getRawPtr(CCLayerImpl* ptr) { return ptr; }
+
+    inline LayerType* currentLayer() const { return currentLayerRepresentsTargetRenderSurface() ? targetRenderSurfaceLayer() : getRawPtr(targetRenderSurfaceChildren()[m_currentLayerIndex]); }
+
+    inline bool currentLayerRepresentsContributingRenderSurface() const { return CCLayerTreeHostCommon::renderSurfaceContributesToTarget<LayerType>(currentLayer(), targetRenderSurfaceLayer()->id()); }
+    inline bool currentLayerRepresentsTargetRenderSurface() const { return m_currentLayerIndex == CCLayerIteratorValue::LayerIndexRepresentingTargetRenderSurface; }
+
+    inline RenderSurfaceType* targetRenderSurface() const { return targetRenderSurfaceLayer()->renderSurface(); }
+    inline const LayerList& targetRenderSurfaceChildren() const { return targetRenderSurface()->layerList(); }
+
+    IteratorActionType m_actions;
+    const LayerList* m_renderSurfaceLayerList;
+
+    // The iterator's current position.
+
+    // A position in the renderSurfaceLayerList. This points to a layer which owns the current target surface.
+    // This is a value from 0 to n-1 (n = size of renderSurfaceLayerList = number of surfaces). A value outside of
+    // this range (for example, CCLayerIteratorValue::InvalidTargetRenderSurfaceLayerIndex) is used to
+    // indicate a position outside the bounds of the tree.
+    int m_targetRenderSurfaceLayerIndex;
+    // A position in the list of layers that are children of the current target surface. When pointing to one of
+    // these layers, this is a value from 0 to n-1 (n = number of children). Since the iterator must also stop at
+    // the layers representing the target surface, this is done by setting the currentLayerIndex to a value of
+    // CCLayerIteratorValue::LayerRepresentingTargetRenderSurface.
+    int m_currentLayerIndex;
+
+    friend struct CCLayerIteratorActions;
+};
+
+// Orderings for iterating over the RenderSurface-Layer tree.
+struct CCLayerIteratorActions {
+    // Walks layers sorted by z-order from back to front.
+    class BackToFront {
+    public:
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void begin(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void end(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void next(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+
+    private:
+        int m_highestTargetRenderSurfaceLayer;
+    };
+
+    // Walks layers sorted by z-order from front to back
+    class FrontToBack {
+    public:
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void begin(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void end(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void next(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+
+    private:
+        template <typename LayerType, typename LayerList, typename RenderSurfaceType, typename ActionType>
+        void goToHighestInSubtree(CCLayerIterator<LayerType, LayerList, RenderSurfaceType, ActionType>&);
+    };
+};
+
+} // namespace cc
+
+#endif