SkLayerDrawLooper.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 SkLayerDrawLooper_DEFINED
#define SkLayerDrawLooper_DEFINED
 
#include "include/core/SkBlendMode.h"
#include "include/core/SkDrawLooper.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPoint.h"
 
#ifndef SK_SUPPORT_LEGACY_DRAWLOOPER
#error "SkDrawLooper is unsupported"
#endif
 
class SK_API SkLayerDrawLooper : public SkDrawLooper {
public:
    ~SkLayerDrawLooper() override;
 
    enum Bits {
        kStyle_Bit      = 1 << 0,   
        kPathEffect_Bit = 1 << 2,   
        kMaskFilter_Bit = 1 << 3,   
        kShader_Bit     = 1 << 4,   
        kColorFilter_Bit = 1 << 5,  
        kXfermode_Bit   = 1 << 6,   
 
        // unsupported kTextSkewX_Bit  = 1 << 1,
 
        kEntirePaint_Bits = -1
 
    };
    typedef int32_t BitFlags;
 
    struct SK_API LayerInfo {
        BitFlags    fPaintBits;
        SkBlendMode fColorMode;
        SkVector    fOffset;
        bool        fPostTranslate; 
 
        LayerInfo();
    };
 
    SkDrawLooper::Context* makeContext(SkArenaAlloc*) const override;
 
    bool asABlurShadow(BlurShadowRec* rec) const override;
 
protected:
    SkLayerDrawLooper();
 
    void flatten(SkWriteBuffer&) const override;
 
private:
    SK_FLATTENABLE_HOOKS(SkLayerDrawLooper)
 
    struct Rec {
        Rec*    fNext;
        SkPaint fPaint;
        LayerInfo fInfo;
    };
    Rec*    fRecs;
    int     fCount;
 
    // state-machine during the init/next cycle
    class LayerDrawLooperContext : public SkDrawLooper::Context {
    public:
        explicit LayerDrawLooperContext(const SkLayerDrawLooper* looper);
 
    protected:
        bool next(Info*, SkPaint* paint) override;
 
    private:
        Rec* fCurrRec;
 
        static void ApplyInfo(SkPaint* dst, const SkPaint& src, const LayerInfo&);
    };
 
    using INHERITED = SkDrawLooper;
 
public:
    class SK_API Builder {
    public:
        Builder();
 
        ~Builder();
 
        SkPaint* addLayer(const LayerInfo&);
 
        void addLayer(SkScalar dx, SkScalar dy);
 
        void addLayer() { this->addLayer(0, 0); }
 
        SkPaint* addLayerOnTop(const LayerInfo&);
 
        sk_sp<SkDrawLooper> detach();
 
    private:
        Builder(const Builder&) = delete;
        Builder& operator=(const Builder&) = delete;
 
        Rec* fRecs;
        Rec* fTopRec;
        int  fCount;
    };
};
 
#endif