SkPathEffect.h revision d3521f1a8dc07fe84d6a8f2151b0c176ff1ec8ca 
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    /**
38     *  Compute a conservative bounds for its effect, given the src bounds.
39     *  The baseline implementation just assigns src to dst.
40     */
41    virtual void computeFastBounds(SkRect* dst, const SkRect& src);
42
43protected:
44    SkPathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
45
46private:
47    // illegal
48    SkPathEffect(const SkPathEffect&);
49    SkPathEffect& operator=(const SkPathEffect&);
50
51    typedef SkFlattenable INHERITED;
52};
53
54/** \class SkPairPathEffect
55
56    Common baseclass for Compose and Sum. This subclass manages two pathEffects,
57    including flattening them. It does nothing in filterPath, and is only useful
58    for managing the lifetimes of its two arguments.
59*/
60class SkPairPathEffect : public SkPathEffect {
61public:
62    SkPairPathEffect(SkPathEffect* pe0, SkPathEffect* pe1);
63    virtual ~SkPairPathEffect();
64
65protected:
66    SkPairPathEffect(SkFlattenableReadBuffer&);
67    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
68
69    // these are visible to our subclasses
70    SkPathEffect* fPE0, *fPE1;
71
72private:
73    typedef SkPathEffect INHERITED;
74};
75
76/** \class SkComposePathEffect
77
78    This subclass of SkPathEffect composes its two arguments, to create
79    a compound pathEffect.
80*/
81class SkComposePathEffect : public SkPairPathEffect {
82public:
83    /** Construct a pathEffect whose effect is to apply first the inner pathEffect
84        and the the outer pathEffect (e.g. outer(inner(path)))
85        The reference counts for outer and inner are both incremented in the constructor,
86        and decremented in the destructor.
87    */
88    SkComposePathEffect(SkPathEffect* outer, SkPathEffect* inner)
89        : INHERITED(outer, inner) {}
90
91    // overrides
92
93    virtual bool filterPath(SkPath* dst, const SkPath& src, SkScalar* width);
94
95    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkComposePathEffect)
96
97protected:
98    SkComposePathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
99
100private:
101    // illegal
102    SkComposePathEffect(const SkComposePathEffect&);
103    SkComposePathEffect& operator=(const SkComposePathEffect&);
104
105    typedef SkPairPathEffect INHERITED;
106};
107
108/** \class SkSumPathEffect
109
110    This subclass of SkPathEffect applies two pathEffects, one after the other.
111    Its filterPath() returns true if either of the effects succeeded.
112*/
113class SkSumPathEffect : public SkPairPathEffect {
114public:
115    /** Construct a pathEffect whose effect is to apply two effects, in sequence.
116        (e.g. first(path) + second(path))
117        The reference counts for first and second are both incremented in the constructor,
118        and decremented in the destructor.
119    */
120    SkSumPathEffect(SkPathEffect* first, SkPathEffect* second)
121        : INHERITED(first, second) {}
122
123    // overrides
124    virtual bool filterPath(SkPath* dst, const SkPath& src, SkScalar* width);
125
126    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkSumPathEffect)
127
128protected:
129    SkSumPathEffect(SkFlattenableReadBuffer& buffer) : INHERITED(buffer) {}
130
131private:
132    // illegal
133    SkSumPathEffect(const SkSumPathEffect&);
134    SkSumPathEffect& operator=(const SkSumPathEffect&);
135
136    typedef SkPairPathEffect INHERITED;
137};
138
139#endif
140
141