SkPerspIter.h revision 80bacfeb4bda06541e8695bd502229727bccfeab 
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 SkPerspIter_DEFINED
11#define SkPerspIter_DEFINED
12
13#include "SkMatrix.h"
14
15class SkPerspIter {
16public:
17    /** Iterate a line through the matrix [x,y] ... [x+count-1, y].
18        @param m    The matrix we will be iterating a line through
19        @param x    The initial X coordinate to be mapped through the matrix
20        @param y    The initial Y coordinate to be mapped through the matrix
21        @param count The number of points (x,y) (x+1,y) (x+2,y) ... we will eventually map
22    */
23    SkPerspIter(const SkMatrix& m, SkScalar x, SkScalar y, int count);
24
25    /** Return the buffer of [x,y] fixed point values we will be filling.
26        This always returns the same value, so it can be saved across calls to
27        next().
28    */
29    const SkFixed* getXY() const { return fStorage; }
30
31    /** Return the number of [x,y] pairs that have been filled in the getXY() buffer.
32        When this returns 0, the iterator is finished.
33    */
34    int next();
35
36private:
37    enum {
38        kShift  = 4,
39        kCount  = (1 << kShift)
40    };
41    const SkMatrix& fMatrix;
42    SkFixed         fStorage[kCount * 2];
43    SkFixed         fX, fY;
44    SkScalar        fSX, fSY;
45    int             fCount;
46};
47
48#endif
49