SkPathEffect.h revision d26147adbbdca85f07dff432025afee0c8614387 
1
2/*
3 * Copyright 2006 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10#ifndef SkPathEffect_DEFINED
11#define SkPathEffect_DEFINED
12
13#include "SkFlattenable.h"
14
15class SkPath;
16
17/** \class SkPathEffect
18
19    SkPathEffect is the base class for objects in the SkPaint that affect
20    the geometry of a drawing primitive before it is transformed by the
21    canvas' matrix and drawn.
22
23    Dashing is implemented as a subclass of SkPathEffect.
24*/
25class SK_API SkPathEffect : public SkFlattenable {
26public:
27    SkPathEffect() {}
28
29    /** Given a src path and a width value, return true if the patheffect
30        has produced a new path (dst) and a new width value. If false is returned,
31        ignore dst and width.
32        On input, width >= 0 means the src should be stroked
33        On output, width >= 0 means the dst should be stroked
34    */
35    virtual bool filterPath(SkPath* dst, const SkPath& src, SkScalar* width) = 0;
36
37    SK_DECLARE_FLATTENABLE_REGISTRAR()
38private:
39    // illegal
40    SkPathEffect(const SkPathEffect&);
41    SkPathEffect& operator=(const SkPathEffect&);
42};
43
44/** \class SkPairPathEffect
45
46    Common baseclass for Compose and Sum. This subclass manages two pathEffects,
47    including flattening them. It does nothing in filterPath, and is only useful
48    for managing the lifetimes of its two arguments.
49*/
50class SkPairPathEffect : public SkPathEffect {
51public:
52    SkPairPathEffect(SkPathEffect* pe0, SkPathEffect* pe1);
53    virtual ~SkPairPathEffect();
54
55protected:
56    SkPairPathEffect(SkFlattenableReadBuffer&);
57    virtual void flatten(SkFlattenableWriteBuffer&) SK_OVERRIDE;
58    // these are visible to our subclasses
59    SkPathEffect* fPE0, *fPE1;
60
61private:
62    typedef SkPathEffect INHERITED;
63};
64
65/** \class SkComposePathEffect
66
67    This subclass of SkPathEffect composes its two arguments, to create
68    a compound pathEffect.
69*/
70class SkComposePathEffect : public SkPairPathEffect {
71public:
72    /** Construct a pathEffect whose effect is to apply first the inner pathEffect
73        and the the outer pathEffect (e.g. outer(inner(path)))
74        The reference counts for outer and inner are both incremented in the constructor,
75        and decremented in the destructor.
76    */
77    SkComposePathEffect(SkPathEffect* outer, SkPathEffect* inner)
78        : INHERITED(outer, inner) {}
79
80    // overrides
81
82    virtual bool filterPath(SkPath* dst, const SkPath& src, SkScalar* width);
83
84    static SkFlattenable* CreateProc(SkFlattenableReadBuffer& buffer) {
85        return SkNEW_ARGS(SkComposePathEffect, (buffer));
86    }
87
88protected:
89    virtual Factory getFactory() SK_OVERRIDE { return CreateProc; }
90
91private:
92    SkComposePathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
93
94    // illegal
95    SkComposePathEffect(const SkComposePathEffect&);
96    SkComposePathEffect& operator=(const SkComposePathEffect&);
97
98    typedef SkPairPathEffect INHERITED;
99};
100
101/** \class SkSumPathEffect
102
103    This subclass of SkPathEffect applies two pathEffects, one after the other.
104    Its filterPath() returns true if either of the effects succeeded.
105*/
106class SkSumPathEffect : public SkPairPathEffect {
107public:
108    /** Construct a pathEffect whose effect is to apply two effects, in sequence.
109        (e.g. first(path) + second(path))
110        The reference counts for first and second are both incremented in the constructor,
111        and decremented in the destructor.
112    */
113    SkSumPathEffect(SkPathEffect* first, SkPathEffect* second)
114        : INHERITED(first, second) {}
115
116    // overrides
117    virtual bool filterPath(SkPath* dst, const SkPath& src, SkScalar* width);
118
119    static SkFlattenable* CreateProc(SkFlattenableReadBuffer& buffer)  {
120        return SkNEW_ARGS(SkSumPathEffect, (buffer));
121    }
122
123protected:
124    virtual Factory getFactory() SK_OVERRIDE { return CreateProc; }
125
126private:
127    SkSumPathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
128
129    // illegal
130    SkSumPathEffect(const SkSumPathEffect&);
131    SkSumPathEffect& operator=(const SkSumPathEffect&);
132
133    typedef SkPairPathEffect INHERITED;
134};
135
136#endif
137
138