1 /*
2  * Copyright 2006 The Android Open Source Project
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 SkPathMeasure_DEFINED
9 #define SkPathMeasure_DEFINED
10 
11 #include "SkPath.h"
12 #include "SkTDArray.h"
13 
14 struct SkConic;
15 
16 class SK_API SkPathMeasure : SkNoncopyable {
17 public:
18     SkPathMeasure();
19     /** Initialize the pathmeasure with the specified path. The path must remain valid
20         for the lifetime of the measure object, or until setPath() is called with
21         a different path (or null), since the measure object keeps a pointer to the
22         path object (does not copy its data).
23     */
24     SkPathMeasure(const SkPath& path, bool forceClosed);
25     ~SkPathMeasure();
26 
27     /** Reset the pathmeasure with the specified path. The path must remain valid
28         for the lifetime of the measure object, or until setPath() is called with
29         a different path (or null), since the measure object keeps a pointer to the
30         path object (does not copy its data).
31     */
32     void setPath(const SkPath*, bool forceClosed);
33 
34     /** Return the total length of the current contour, or 0 if no path
35         is associated (e.g. resetPath(null))
36     */
37     SkScalar getLength();
38 
39     /** Pins distance to 0 <= distance <= getLength(), and then computes
40         the corresponding position and tangent.
41         Returns false if there is no path, or a zero-length path was specified, in which case
42         position and tangent are unchanged.
43     */
44     bool SK_WARN_UNUSED_RESULT getPosTan(SkScalar distance, SkPoint* position,
45                                          SkVector* tangent);
46 
47     enum MatrixFlags {
48         kGetPosition_MatrixFlag     = 0x01,
49         kGetTangent_MatrixFlag      = 0x02,
50         kGetPosAndTan_MatrixFlag    = kGetPosition_MatrixFlag | kGetTangent_MatrixFlag
51     };
52 
53     /** Pins distance to 0 <= distance <= getLength(), and then computes
54         the corresponding matrix (by calling getPosTan).
55         Returns false if there is no path, or a zero-length path was specified, in which case
56         matrix is unchanged.
57     */
58     bool SK_WARN_UNUSED_RESULT getMatrix(SkScalar distance, SkMatrix* matrix,
59                                   MatrixFlags flags = kGetPosAndTan_MatrixFlag);
60 
61     /** Given a start and stop distance, return in dst the intervening segment(s).
62         If the segment is zero-length, return false, else return true.
63         startD and stopD are pinned to legal values (0..getLength()). If startD <= stopD
64         then return false (and leave dst untouched).
65         Begin the segment with a moveTo if startWithMoveTo is true
66     */
67     bool getSegment(SkScalar startD, SkScalar stopD, SkPath* dst, bool startWithMoveTo);
68 
69     /** Return true if the current contour is closed()
70     */
71     bool isClosed();
72 
73     /** Move to the next contour in the path. Return true if one exists, or false if
74         we're done with the path.
75     */
76     bool nextContour();
77 
78 #ifdef SK_DEBUG
79     void    dump();
80 #endif
81 
82 private:
83     SkPath::Iter    fIter;
84     const SkPath*   fPath;
85     SkScalar        fLength;            // relative to the current contour
86     int             fFirstPtIndex;      // relative to the current contour
87     bool            fIsClosed;          // relative to the current contour
88     bool            fForceClosed;
89 
90     struct Segment {
91         SkScalar    fDistance;  // total distance up to this point
92         unsigned    fPtIndex : 15; // index into the fPts array
93         unsigned    fTValue : 15;
94         unsigned    fType : 2;
95 
96         SkScalar getScalarT() const;
97     };
98     SkTDArray<Segment>  fSegments;
99     SkTDArray<SkPoint>  fPts; // Points used to define the segments
100 
101     static const Segment* NextSegment(const Segment*);
102 
103     void     buildSegments();
104     SkScalar compute_quad_segs(const SkPoint pts[3], SkScalar distance,
105                                 int mint, int maxt, int ptIndex);
106     SkScalar compute_conic_segs(const SkConic&, SkScalar distance, int mint, int maxt, int ptIndex);
107     SkScalar compute_cubic_segs(const SkPoint pts[3], SkScalar distance,
108                                 int mint, int maxt, int ptIndex);
109     const Segment* distanceToSegment(SkScalar distance, SkScalar* t);
110 };
111 
112 #endif
113