1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
/*
* 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 GrPathRenderer_DEFINED
#define GrPathRenderer_DEFINED
#include "GrDrawTarget.h"
#include "GrPathRendererChain.h"
#include "SkTArray.h"
class SkPath;
struct GrPoint;
/**
* Base class for drawing paths into a GrDrawTarget.
* Paths may be drawn multiple times as when tiling for supersampling. The
* calls on GrPathRenderer to draw a path will look like this:
*
* pr->setPath(target, path, fill, aa, translate); // sets the path to draw
* pr->drawPath(...); // draw the path
* pr->drawPath(...);
* ...
* pr->clearPath(); // finished with the path
*/
class GR_API GrPathRenderer : public GrRefCnt {
public:
/**
* This is called to install custom path renderers in every GrContext at
* create time. The default implementation in GrCreatePathRenderer_none.cpp
* does not add any additional renderers. Link against another
* implementation to install your own. The first added is the most preferred
* path renderer, second is second most preferred, etc.
*
* @param context the context that will use the path renderer
* @param flags flags indicating how path renderers will be used
* @param prChain the chain to add path renderers to.
*/
static void AddPathRenderers(GrContext* context,
GrPathRendererChain::UsageFlags flags,
GrPathRendererChain* prChain);
GrPathRenderer();
/**
* For complex clips Gr uses the stencil buffer. The path renderer must be
* able to render paths into the stencil buffer. However, the path renderer
* itself may require the stencil buffer to resolve the path fill rule.
* This function queries whether the path render needs its own stencil
* pass. If this returns false then drawPath() should not modify the
* the target's stencil settings but use those already set on target. The
* target is passed as a param in case the answer depends upon draw state.
* The view matrix and render target set on the draw target may change
* before setPath/drawPath is called and so shouldn't be considered.
*
* @param target target that the path will be rendered to
* @param path the path that will be drawn
* @param fill the fill rule that will be used, will never be an inverse
* rule.
*
* @return false if this path renderer can generate interior-only fragments
* without changing the stencil settings on the target. If it
* returns true the drawPathToStencil will be used when rendering
* clips.
*/
virtual bool requiresStencilPass(const SkPath& path,
GrPathFill fill,
const GrDrawTarget* target) const {
return false;
}
virtual bool canDrawPath(const SkPath& path,
GrPathFill fill,
const GrDrawTarget* target,
bool antiAlias) const = 0;
/**
* Draws the path into the draw target. If requiresStencilBuffer returned
* false then the target may be setup for stencil rendering (since the
* path renderer didn't claim that it needs to use the stencil internally).
*
* @param stages bitfield that indicates which stages are
* in use. All enabled stages expect positions
* as texture coordinates. The path renderer
* use the remaining stages for its path
* filling algorithm.
*/
virtual bool drawPath(const SkPath& path,
GrPathFill fill,
const GrVec* translate,
GrDrawTarget* target,
GrDrawState::StageMask stageMask,
bool antiAlias) {
GrAssert(this->canDrawPath(path, fill, target, antiAlias));
return this->onDrawPath(path, fill, translate,
target, stageMask, antiAlias);
}
/**
* Draws the path to the stencil buffer. Assume the writable stencil bits
* are already initialized to zero. Fill will always be either
* kWinding_PathFill or kEvenOdd_PathFill.
*
* Only called if requiresStencilPass returns true for the same combo of
* target, path, and fill. Never called with an inverse fill.
*
* The default implementation assumes the path filling algorithm doesn't
* require a separate stencil pass and so crashes.
*
*/
virtual void drawPathToStencil(const SkPath& path,
GrPathFill fill,
GrDrawTarget* target) {
GrCrash("Unexpected call to drawPathToStencil.");
}
protected:
virtual bool onDrawPath(const SkPath& path,
GrPathFill fill,
const GrVec* translate,
GrDrawTarget* target,
GrDrawState::StageMask stageMask,
bool antiAlias) = 0;
private:
typedef GrRefCnt INHERITED;
};
#endif
|
