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 "include/core/SkPoint.h"
12 #include "include/core/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  */
21 struct SkRSXform {
MakeSkRSXform22     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      */
MakeFromRadiansSkRSXform33     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 
rectStaysRectSkRSXform45     bool rectStaysRect() const {
46         return 0 == fSCos || 0 == fSSin;
47     }
48 
setIdentitySkRSXform49     void setIdentity() {
50         fSCos = 1;
51         fSSin = fTx = fTy = 0;
52     }
53 
setSkRSXform54     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;
toQuadSkRSXform62     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