1 #include "SkMatrix.h"
2
3 typedef int64_t SkDScalar;
4
SkDScalar_toScalar(SkDScalar value)5 static SkScalar SkDScalar_toScalar(SkDScalar value) {
6 SkDScalar result = (value + (1 << 15)) >> 16;
7 int top = result >> 31;
8 SkASSERT(top == 0 || top == -1);
9 return (SkScalar)result;
10 }
11
SkDScalar_setMul(SkScalar a,SkScalar b)12 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
13 return (SkDScalar)a * b;
14 }
15
computeOuterProduct(SkMatrix * matrix,const SkPoint pts0[3],const SkPoint & ave0,const SkPoint pts1[3],const SkPoint & ave1)16 static void computeOuterProduct(SkMatrix* matrix,
17 const SkPoint pts0[3], const SkPoint& ave0,
18 const SkPoint pts1[3], const SkPoint& ave1) {
19 SkDScalar tmp[4];
20 sk_bzero(tmp, sizeof(tmp));
21
22 for (int i = 0; i < 3; i++) {
23 SkScalar x0 = pts0[i].fX - ave0.fX;
24 SkScalar y0 = pts0[i].fY - ave0.fY;
25 SkScalar x1 = pts1[i].fX - ave1.fX;
26 SkScalar y1 = pts1[i].fY - ave1.fY;
27 tmp[0] += SkDScalar_setMul(x0, x1);
28 tmp[1] += SkDScalar_setMul(x0, y1);
29 tmp[2] += SkDScalar_setMul(y0, x1);
30 tmp[3] += SkDScalar_setMul(y0, y1);
31 }
32 matrix->reset();
33 matrix->setScaleX(SkDScalar_toScalar(tmp[0]));
34 matrix->setSkewY( SkDScalar_toScalar(tmp[1]));
35 matrix->setSkewX( SkDScalar_toScalar(tmp[2]));
36 matrix->setScaleY(SkDScalar_toScalar(tmp[3]));
37 }
38
dot(SkScalar ax,SkScalar ay,SkScalar bx,SkScalar by)39 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
40 return SkDScalar_toScalar(SkDScalar_setMul(ax, bx) +
41 SkDScalar_setMul(ay, by));
42 }
43
SkSetPoly3To3(SkMatrix * matrix,const SkPoint src[3],const SkPoint dst[3])44 bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) {
45 const SkPoint& srcAve = src[0];
46 const SkPoint& dstAve = dst[0];
47
48 SkMatrix srcOP, dstOP;
49
50 computeOuterProduct(&srcOP, src, srcAve, src, srcAve);
51
52 if (!srcOP.invert(&srcOP)) {
53 return false;
54 }
55
56 computeOuterProduct(&dstOP, src, srcAve, dst, dstAve);
57
58 matrix->setConcat(dstOP, srcOP);
59 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY,
60 matrix->getScaleX(), matrix->getSkewX()));
61 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY,
62 matrix->getSkewY(), matrix->getScaleY()));
63 return true;
64 }
65
66