1 #include "SkMatrix.h"
2
3 #ifdef SK_SCALAR_IS_FIXED
4 typedef int64_t SkDScalar;
5
SkDScalar_toScalar(SkDScalar value)6 static SkScalar SkDScalar_toScalar(SkDScalar value) {
7 SkDScalar result = (value + (1 << 15)) >> 16;
8 int top = result >> 31;
9 SkASSERT(top == 0 || top == -1);
10 return (SkScalar)result;
11 }
div(SkDScalar numer,SkDScalar denom)12 static SkScalar div(SkDScalar numer, SkDScalar denom) {
13 denom >>= 16;
14 return numer / denom;
15 }
16 #else
17 typedef double SkDScalar;
18
SkDScalar_toScalar(SkDScalar value)19 static SkScalar SkDScalar_toScalar(SkDScalar value) {
20 return static_cast<float>(value);
21 }
div(SkDScalar numer,SkDScalar denom)22 static SkScalar div(SkDScalar numer, SkDScalar denom) {
23 return static_cast<float>(numer / denom);
24 }
25 #endif
26
SkDScalar_setMul(SkScalar a,SkScalar b)27 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
28 return (SkDScalar)a * b;
29 }
30
computeOuterProduct(SkScalar op[4],const SkPoint pts0[3],const SkPoint & ave0,const SkPoint pts1[3],const SkPoint & ave1)31 static void computeOuterProduct(SkScalar op[4],
32 const SkPoint pts0[3], const SkPoint& ave0,
33 const SkPoint pts1[3], const SkPoint& ave1) {
34 sk_bzero(op, 4 * sizeof(op[0]));
35 for (int i = 0; i < 3; i++) {
36 SkScalar x0 = pts0[i].fX - ave0.fX;
37 SkScalar y0 = pts0[i].fY - ave0.fY;
38 SkScalar x1 = pts1[i].fX - ave1.fX;
39 SkScalar y1 = pts1[i].fY - ave1.fY;
40 op[0] += SkScalarMul(x0, x1);
41 op[1] += SkScalarMul(x0, y1);
42 op[2] += SkScalarMul(y0, x1);
43 op[3] += SkScalarMul(y0, y1);
44 }
45 }
46
ddot(SkScalar ax,SkScalar ay,SkScalar bx,SkScalar by)47 static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
48 return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by);
49 }
50
dot(SkScalar ax,SkScalar ay,SkScalar bx,SkScalar by)51 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
52 return SkDScalar_toScalar(ddot(ax, ay, bx, by));
53 }
54
SkSetPoly3To3(SkMatrix * matrix,const SkPoint src[3],const SkPoint dst[3])55 bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) {
56 const SkPoint& srcAve = src[0];
57 const SkPoint& dstAve = dst[0];
58
59 SkScalar srcOP[4], dstOP[4];
60
61 computeOuterProduct(srcOP, src, srcAve, src, srcAve);
62 computeOuterProduct(dstOP, src, srcAve, dst, dstAve);
63
64 SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) -
65 SkDScalar_setMul(srcOP[1], srcOP[2]);
66
67 SkDScalar M[4];
68
69 const SkScalar srcOP0 = srcOP[3];
70 const SkScalar srcOP1 = -srcOP[1];
71 const SkScalar srcOP2 = -srcOP[2];
72 const SkScalar srcOP3 = srcOP[0];
73
74 M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]);
75 M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]);
76 M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]);
77 M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]);
78
79 matrix->reset();
80 matrix->setScaleX(div(M[0], det));
81 matrix->setSkewX( div(M[1], det));
82 matrix->setSkewY (div(M[2], det));
83 matrix->setScaleY(div(M[3], det));
84 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY,
85 matrix->getScaleX(), matrix->getSkewX()));
86 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY,
87 matrix->getSkewY(), matrix->getScaleY()));
88 return true;
89 }
90
91