1/*
2 * Copyright 2015 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
8#ifndef SkRSXform_DEFINED
9#define SkRSXform_DEFINED
10
11#include "SkPoint.h"
12#include "SkSize.h"
13
14/**
15 *  A compressed form of a rotation+scale matrix.
16 *
17 *  [ fSCos     -fSSin    fTx ]
18 *  [ fSSin      fSCos    fTy ]
19 *  [     0          0      1 ]
20 */
21struct SkRSXform {
22    static SkRSXform Make(SkScalar scos, SkScalar ssin, SkScalar tx, SkScalar ty) {
23        SkRSXform xform = { scos, ssin, tx, ty };
24        return xform;
25    }
26
27    /*
28     *  Initialize a new xform based on the scale, rotation (in radians), final tx,ty location
29     *  and anchor-point ax,ay within the src quad.
30     *
31     *  Note: the anchor point is not normalized (e.g. 0...1) but is in pixels of the src image.
32     */
33    static SkRSXform MakeFromRadians(SkScalar scale, SkScalar radians, SkScalar tx, SkScalar ty,
34                                     SkScalar ax, SkScalar ay) {
35        const SkScalar s = SkScalarSin(radians) * scale;
36        const SkScalar c = SkScalarCos(radians) * scale;
37        return Make(c, s, tx + -c * ax + s * ay, ty + -s * ax - c * ay);
38    }
39
40    SkScalar fSCos;
41    SkScalar fSSin;
42    SkScalar fTx;
43    SkScalar fTy;
44
45    bool rectStaysRect() const {
46        return 0 == fSCos || 0 == fSSin;
47    }
48
49    void setIdentity() {
50        fSCos = 1;
51        fSSin = fTx = fTy = 0;
52    }
53
54    void set(SkScalar scos, SkScalar ssin, SkScalar tx, SkScalar ty) {
55        fSCos = scos;
56        fSSin = ssin;
57        fTx = tx;
58        fTy = ty;
59    }
60
61    void toQuad(SkScalar width, SkScalar height, SkPoint quad[4]) const;
62    void toQuad(const SkSize& size, SkPoint quad[4]) const {
63        this->toQuad(size.width(), size.height(), quad);
64    }
65    void toTriStrip(SkScalar width, SkScalar height, SkPoint strip[4]) const;
66};
67
68#endif
69
70