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      1 /*
      2  * Copyright 2018 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkSGGradient_DEFINED
      9 #define SkSGGradient_DEFINED
     10 
     11 #include "SkSGPaintNode.h"
     12 
     13 #include "SkColor.h"
     14 #include "SkPoint.h"
     15 #include "SkScalar.h"
     16 #include "SkShader.h"
     17 
     18 #include <vector>
     19 
     20 namespace sksg {
     21 
     22 /**
     23  * Gradient base class.
     24  */
     25 class Gradient : public PaintNode {
     26 public:
     27     struct ColorStop {
     28         SkScalar fPosition;
     29         SkColor  fColor;
     30 
     31         bool operator==(const ColorStop& other) const {
     32             return fPosition == other.fPosition && fColor == other.fColor;
     33         }
     34     };
     35 
     36     SG_ATTRIBUTE(ColorStops, std::vector<ColorStop>, fColorStops)
     37     SG_ATTRIBUTE(TileMode  , SkShader::TileMode    , fTileMode  )
     38 
     39 protected:
     40     void onApplyToPaint(SkPaint*) const final;
     41 
     42     virtual sk_sp<SkShader> onMakeShader(const std::vector<SkColor>& colors,
     43                                          const std::vector<SkScalar>& positions) const = 0;
     44 
     45 protected:
     46     Gradient() = default;
     47 
     48 private:
     49     std::vector<ColorStop> fColorStops;
     50     SkShader::TileMode     fTileMode = SkShader::kClamp_TileMode;
     51 
     52     using INHERITED = PaintNode;
     53 };
     54 
     55 class LinearGradient final : public Gradient {
     56 public:
     57     static sk_sp<LinearGradient> Make() {
     58         return sk_sp<LinearGradient>(new LinearGradient());
     59     }
     60 
     61     SG_ATTRIBUTE(StartPoint, SkPoint, fStartPoint)
     62     SG_ATTRIBUTE(EndPoint  , SkPoint, fEndPoint  )
     63 
     64 protected:
     65     sk_sp<SkShader> onMakeShader(const std::vector<SkColor>& colors,
     66                                  const std::vector<SkScalar>& positions) const override;
     67 
     68 private:
     69     LinearGradient() = default;
     70 
     71     SkPoint fStartPoint = SkPoint::Make(0, 0),
     72             fEndPoint   = SkPoint::Make(0, 0);
     73 
     74     using INHERITED = Gradient;
     75 };
     76 
     77 class RadialGradient final : public Gradient {
     78 public:
     79     static sk_sp<RadialGradient> Make() {
     80         return sk_sp<RadialGradient>(new RadialGradient());
     81     }
     82 
     83     SG_ATTRIBUTE(StartCenter, SkPoint , fStartCenter)
     84     SG_ATTRIBUTE(EndCenter  , SkPoint , fEndCenter  )
     85     SG_ATTRIBUTE(StartRadius, SkScalar, fStartRadius)
     86     SG_ATTRIBUTE(EndRadius  , SkScalar, fEndRadius  )
     87 
     88 protected:
     89     sk_sp<SkShader> onMakeShader(const std::vector<SkColor>& colors,
     90                                  const std::vector<SkScalar>& positions) const override;
     91 
     92 private:
     93     RadialGradient() = default;
     94 
     95     SkPoint  fStartCenter = SkPoint::Make(0, 0),
     96              fEndCenter   = SkPoint::Make(0, 0);
     97     SkScalar fStartRadius = 0,
     98              fEndRadius   = 0;
     99 
    100     using INHERITED = Gradient;
    101 };
    102 
    103 } // namespace sksg
    104 
    105 #endif // SkSGGradient_DEFINED
    106