SkPathOps.h revision ba9a4aa8550c982c480d03cb6ba2cabaf6209b41 
1/*
2 * Copyright 2012 Google Inc.
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#ifndef SkPathOps_DEFINED
8#define SkPathOps_DEFINED
9
10#include "SkPreConfig.h"
11#include "SkTArray.h"
12#include "SkTDArray.h"
13
14class SkPath;
15struct SkRect;
16
17
18// FIXME: remove this once the define in src/skia/SkUserConfig.h lands
19#ifndef SK_SUPPORT_LEGACY_PATHOP_ENUMS
20#define SK_SUPPORT_LEGACY_PATHOP_ENUMS
21#endif
22
23// FIXME: move everything below into the SkPath class
24/**
25  *  The logical operations that can be performed when combining two paths.
26  */
27enum SkPathOp {
28    kDifference_SkPathOp,         //!< subtract the op path from the first path
29    kIntersect_SkPathOp,          //!< intersect the two paths
30    kUnion_SkPathOp,              //!< union (inclusive-or) the two paths
31    kXOR_SkPathOp,                //!< exclusive-or the two paths
32    kReverseDifference_SkPathOp,  //!< subtract the first path from the op path
33
34#ifdef SK_SUPPORT_LEGACY_PATHOP_ENUMS
35    kDifference_PathOp = 0,     //!< subtract the op path from the first path
36    kIntersect_PathOp,          //!< intersect the two paths
37    kUnion_PathOp,              //!< union (inclusive-or) the two paths
38    kXOR_PathOp,                //!< exclusive-or the two paths
39    kReverseDifference_PathOp,  //!< subtract the first path from the op path
40#endif
41};
42
43/** Set this path to the result of applying the Op to this path and the
44    specified path: this = (this op operand).
45    The resulting path will be constructed from non-overlapping contours.
46    The curve order is reduced where possible so that cubics may be turned
47    into quadratics, and quadratics maybe turned into lines.
48
49    Returns true if operation was able to produce a result;
50    otherwise, result is unmodified.
51
52    @param one The first operand (for difference, the minuend)
53    @param two The second operand (for difference, the subtrahend)
54    @param op The operator to apply.
55    @param result The product of the operands. The result may be one of the
56                  inputs.
57    @return True if the operation succeeded.
58  */
59bool SK_API Op(const SkPath& one, const SkPath& two, SkPathOp op, SkPath* result);
60
61/** Set this path to a set of non-overlapping contours that describe the
62    same area as the original path.
63    The curve order is reduced where possible so that cubics may
64    be turned into quadratics, and quadratics maybe turned into lines.
65
66    Returns true if operation was able to produce a result;
67    otherwise, result is unmodified.
68
69    @param path The path to simplify.
70    @param result The simplified path. The result may be the input.
71    @return True if simplification succeeded.
72  */
73bool SK_API Simplify(const SkPath& path, SkPath* result);
74
75/** Set the resulting rectangle to the tight bounds of the path.
76
77    @param path The path measured.
78    @param result The tight bounds of the path.
79    @return True if the bounds could be computed.
80  */
81bool SK_API TightBounds(const SkPath& path, SkRect* result);
82
83/** Perform a series of path operations, optimized for unioning many paths together.
84  */
85class SK_API SkOpBuilder {
86public:
87    /** Add one or more paths and their operand. The builder is empty before the first
88        path is added, so the result of a single add is (emptyPath OP path).
89
90        @param path The second operand.
91        @param _operator The operator to apply to the existing and supplied paths.
92     */
93    void add(const SkPath& path, SkPathOp _operator);
94
95    /** Computes the sum of all paths and operands, and resets the builder to its
96        initial state.
97
98        @param result The product of the operands.
99        @return True if the operation succeeded.
100      */
101    bool resolve(SkPath* result);
102
103private:
104    SkTArray<SkPath> fPathRefs;
105    SkTDArray<SkPathOp> fOps;
106
107    void reset();
108};
109
110#endif
111