SkEdgeBuilder.h

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/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#ifndef SkEdgeBuilder_DEFINED
#define SkEdgeBuilder_DEFINED
 
#include "include/core/SkRect.h"
#include "include/private/base/SkTDArray.h"
#include "src/base/SkArenaAlloc.h"
 
#include <cstddef>
 
class SkPath;
struct SkAnalyticEdge;
struct SkEdge;
struct SkPoint;
 
class SkEdgeBuilder {
public:
    int buildEdges(const SkPath& path,
                   const SkIRect* shiftedClip);
 
protected:
    SkEdgeBuilder() = default;
    virtual ~SkEdgeBuilder() = default;
 
    // In general mode we allocate pointers in fList and fEdgeList points to its head.
    // In polygon mode we preallocated edges contiguously in fAlloc and fEdgeList points there.
    void**              fEdgeList = nullptr;
    SkTDArray<void*>    fList;
    SkSTArenaAlloc<512> fAlloc;
 
    enum Combine {
        kNo_Combine,
        kPartial_Combine,
        kTotal_Combine
    };
 
private:
    int build    (const SkPath& path, const SkIRect* clip, bool clipToTheRight);
    int buildPoly(const SkPath& path, const SkIRect* clip, bool clipToTheRight);
 
    virtual char* allocEdges(size_t n, size_t* sizeof_edge) = 0;
    virtual SkRect recoverClip(const SkIRect&) const = 0;
 
    virtual void addLine (const SkPoint pts[]) = 0;
    virtual void addQuad (const SkPoint pts[]) = 0;
    virtual void addCubic(const SkPoint pts[]) = 0;
    virtual Combine addPolyLine(const SkPoint pts[], char* edge, char** edgePtr) = 0;
};
 
class SkBasicEdgeBuilder final : public SkEdgeBuilder {
public:
    explicit SkBasicEdgeBuilder(int clipShift) : fClipShift(clipShift) {}
 
    SkEdge** edgeList() { return (SkEdge**)fEdgeList; }
 
private:
    Combine combineVertical(const SkEdge* edge, SkEdge* last);
 
    char* allocEdges(size_t, size_t*) override;
    SkRect recoverClip(const SkIRect&) const override;
 
    void addLine (const SkPoint pts[]) override;
    void addQuad (const SkPoint pts[]) override;
    void addCubic(const SkPoint pts[]) override;
    Combine addPolyLine(const SkPoint pts[], char* edge, char** edgePtr) override;
 
    const int fClipShift;
};
 
class SkAnalyticEdgeBuilder final : public SkEdgeBuilder {
public:
    SkAnalyticEdgeBuilder() {}
 
    SkAnalyticEdge** analyticEdgeList() { return (SkAnalyticEdge**)fEdgeList; }
 
private:
    Combine combineVertical(const SkAnalyticEdge* edge, SkAnalyticEdge* last);
 
    char* allocEdges(size_t, size_t*) override;
    SkRect recoverClip(const SkIRect&) const override;
 
    void addLine (const SkPoint pts[]) override;
    void addQuad (const SkPoint pts[]) override;
    void addCubic(const SkPoint pts[]) override;
    Combine addPolyLine(const SkPoint pts[], char* edge, char** edgePtr) override;
};
#endif