1 /*
2  * Copyright 2014 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 GrPathRendering_DEFINED
9 #define GrPathRendering_DEFINED
10 
11 #include "SkPath.h"
12 #include "GrPipeline.h"
13 
14 class GrGpu;
15 class GrPath;
16 class GrStencilSettings;
17 class GrStyle;
18 struct SkScalerContextEffects;
19 class SkDescriptor;
20 class SkTypeface;
21 
22 /**
23  * Abstract class wrapping HW path rendering API.
24  *
25  * The subclasses of this class use the possible HW API to render paths (as opposed to path
26  * rendering implemented in Skia on top of a "3d" HW API).
27  * The subclasses hold the global state needed to render paths, including shadow of the global HW
28  * API state. Similar to GrGpu.
29  *
30  * It is expected that the lifetimes of GrGpuXX and GrXXPathRendering are the same. The call context
31  * interface (eg.  * the concrete instance of GrGpu subclass) should be provided to the instance
32  * during construction.
33  */
34 class GrPathRendering {
35 public:
36     virtual ~GrPathRendering() { }
37 
38     enum PathTransformType {
39         kNone_PathTransformType,        //!< []
40         kTranslateX_PathTransformType,  //!< [kMTransX]
41         kTranslateY_PathTransformType,  //!< [kMTransY]
42         kTranslate_PathTransformType,   //!< [kMTransX, kMTransY]
43         kAffine_PathTransformType,      //!< [kMScaleX, kMSkewX, kMTransX, kMSkewY, kMScaleY, kMTransY]
44 
45         kLast_PathTransformType = kAffine_PathTransformType
46     };
47 
48     static inline int PathTransformSize(PathTransformType type) {
49         switch (type) {
50             case kNone_PathTransformType:
51                 return 0;
52             case kTranslateX_PathTransformType:
53             case kTranslateY_PathTransformType:
54                 return 1;
55             case kTranslate_PathTransformType:
56                 return 2;
57             case kAffine_PathTransformType:
58                 return 6;
59 
60             default:
61                 SK_ABORT("Unknown path transform type");
62                 return 0;
63         }
64     }
65 
66     // No native support for inverse at this time
67     enum FillType {
68         /** Specifies that "inside" is computed by a non-zero sum of signed
69             edge crossings
70         */
71         kWinding_FillType,
72         /** Specifies that "inside" is computed by an odd number of edge
73             crossings
74         */
75         kEvenOdd_FillType,
76     };
77 
78     static const GrUserStencilSettings& GetStencilPassSettings(FillType);
79 
80     /**
81      * Creates a new gpu path, based on the specified path and stroke and returns it.
82      *
83      * @param SkPath    the geometry.
84      * @param GrStyle   the style applied to the path. Styles with non-dash path effects are not
85      *                  allowed.
86      * @return a new GPU path object.
87      */
88     virtual sk_sp<GrPath> createPath(const SkPath&, const GrStyle&) = 0;
89 
90     /** None of these params are optional, pointers used just to avoid making copies. */
91     struct StencilPathArgs {
92         StencilPathArgs(bool useHWAA,
93                         GrRenderTargetProxy* proxy,
94                         const SkMatrix* viewMatrix,
95                         const GrScissorState* scissor,
96                         const GrStencilSettings* stencil)
97             : fUseHWAA(useHWAA)
98             , fProxy(proxy)
99             , fViewMatrix(viewMatrix)
100             , fScissor(scissor)
101             , fStencil(stencil) {
102         }
103         bool                     fUseHWAA;
104         GrRenderTargetProxy*     fProxy;
105         const SkMatrix*          fViewMatrix;
106         const GrScissorState*    fScissor;
107         const GrStencilSettings* fStencil;
108     };
109 
110     void stencilPath(const StencilPathArgs& args, const GrPath* path);
111 
112     void drawPath(GrRenderTarget*, GrSurfaceOrigin,
113                   const GrPrimitiveProcessor& primProc,
114                   const GrPipeline& pipeline,
115                   const GrPipeline::FixedDynamicState&,
116                   const GrStencilSettings& stencilPassSettings,  // Cover pass settings in pipeline.
117                   const GrPath* path);
118 
119 protected:
120     GrPathRendering(GrGpu* gpu) : fGpu(gpu) { }
121 
122     virtual void onStencilPath(const StencilPathArgs&, const GrPath*) = 0;
123     virtual void onDrawPath(GrRenderTarget*, GrSurfaceOrigin,
124                             const GrPrimitiveProcessor&,
125                             const GrPipeline&,
126                             const GrPipeline::FixedDynamicState&,
127                             const GrStencilSettings&,
128                             const GrPath*) = 0;
129 
130     GrGpu* fGpu;
131 private:
132     GrPathRendering& operator=(const GrPathRendering&);
133 };
134 
135 #endif
136