SkPathMeasure.h revision 8a1c16ff38322f0210116fa7293eb8817c7e477e 
1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef SkPathMeasure_DEFINED
18#define SkPathMeasure_DEFINED
19
20#include "SkPath.h"
21#include "SkTDArray.h"
22
23class SkPathMeasure : SkNoncopyable {
24public:
25    SkPathMeasure();
26    /** Initialize the pathmeasure with the specified path. The path must remain valid
27        for the lifetime of the measure object, or until setPath() is called with
28        a different path (or null), since the measure object keeps a pointer to the
29        path object (does not copy its data).
30    */
31    SkPathMeasure(const SkPath& path, bool forceClosed);
32    ~SkPathMeasure();
33
34    /** Reset the pathmeasure with the specified path. The path must remain valid
35        for the lifetime of the measure object, or until setPath() is called with
36        a different path (or null), since the measure object keeps a pointer to the
37        path object (does not copy its data).
38    */
39    void    setPath(const SkPath*, bool forceClosed);
40
41    /** Return the total length of the current contour, or 0 if no path
42        is associated (e.g. resetPath(null))
43    */
44    SkScalar getLength();
45
46    /** Pins distance to 0 <= distance <= getLength(), and then computes
47        the corresponding position and tangent.
48        Returns false if there is no path, or a zero-length path was specified, in which case
49        position and tangent are unchanged.
50    */
51    bool getPosTan(SkScalar distance, SkPoint* position, SkVector* tangent);
52
53    enum MatrixFlags {
54        kGetPosition_MatrixFlag     = 0x01,
55        kGetTangent_MatrixFlag      = 0x02,
56        kGetPosAndTan_MatrixFlag    = kGetPosition_MatrixFlag | kGetTangent_MatrixFlag
57    };
58    /** Pins distance to 0 <= distance <= getLength(), and then computes
59        the corresponding matrix (by calling getPosTan).
60        Returns false if there is no path, or a zero-length path was specified, in which case
61        matrix is unchanged.
62    */
63    bool getMatrix(SkScalar distance, SkMatrix* matrix, MatrixFlags flags = kGetPosAndTan_MatrixFlag);
64    /** Given a start and stop distance, return in dst the intervening segment(s).
65        If the segment is zero-length, return false, else return true.
66        startD and stopD are pinned to legal values (0..getLength()). If startD <= stopD
67        then return false (and leave dst untouched).
68        Begin the segment with a moveTo if startWithMoveTo is true
69    */
70    bool getSegment(SkScalar startD, SkScalar stopD, SkPath* dst, bool startWithMoveTo);
71
72    /** Return true if the current contour is closed()
73    */
74    bool isClosed();
75
76    /** Move to the next contour in the path. Return true if one exists, or false if
77        we're done with the path.
78    */
79    bool nextContour();
80
81#ifdef SK_DEBUG
82    void    dump();
83    static void UnitTest();
84#endif
85
86private:
87    SkPath::Iter    fIter;
88    const SkPath*   fPath;
89    SkScalar        fLength;            // relative to the current contour
90    int             fFirstPtIndex;      // relative to the current contour
91    bool            fIsClosed;          // relative to the current contour
92    bool            fForceClosed;
93
94    struct Segment {
95        SkScalar    fDistance;  // total distance up to this point
96        unsigned    fPtIndex : 15;
97        unsigned    fTValue : 15;
98        unsigned    fType : 2;
99
100        SkScalar getScalarT() const;
101    };
102    SkTDArray<Segment>  fSegments;
103
104    static const Segment* NextSegment(const Segment*);
105
106    void     buildSegments();
107    SkScalar compute_quad_segs(const SkPoint pts[3], SkScalar distance,
108                                int mint, int maxt, int ptIndex);
109    SkScalar compute_cubic_segs(const SkPoint pts[3], SkScalar distance,
110                                int mint, int maxt, int ptIndex);
111    const Segment* distanceToSegment(SkScalar distance, SkScalar* t);
112};
113
114#endif
115
116