3 * Copyright 2011 Google Inc.
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
10 // FIXME: needs to be in a header
11 bool SkSetPoly3To3_D(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]);
13 typedef int64_t SkDScalar;
15 static SkScalar SkDScalar_toScalar(SkDScalar value) {
16 SkDScalar result = (value + (1 << 15)) >> 16;
17 SkDEBUGCODE(int top = static_cast<int>(result >> 31);)
18 SkASSERT(top == 0 || top == -1);
19 return (SkScalar)result;
22 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
23 return (SkDScalar) ((SkDScalar) a * (SkDScalar) b);
26 static void computeOuterProduct(SkMatrix* matrix,
27 const SkPoint pts0[3], const SkPoint& ave0,
28 const SkPoint pts1[3], const SkPoint& ave1) {
30 sk_bzero(tmp, sizeof(tmp));
32 for (int i = 0; i < 3; i++) {
33 SkScalar x0 = pts0[i].fX - ave0.fX;
34 SkScalar y0 = pts0[i].fY - ave0.fY;
35 SkScalar x1 = pts1[i].fX - ave1.fX;
36 SkScalar y1 = pts1[i].fY - ave1.fY;
37 tmp[0] += SkDScalar_setMul(x0, x1);
38 tmp[1] += SkDScalar_setMul(x0, y1);
39 tmp[2] += SkDScalar_setMul(y0, x1);
40 tmp[3] += SkDScalar_setMul(y0, y1);
43 matrix->setScaleX(SkDScalar_toScalar(tmp[0]));
44 matrix->setSkewY( SkDScalar_toScalar(tmp[1]));
45 matrix->setSkewX( SkDScalar_toScalar(tmp[2]));
46 matrix->setScaleY(SkDScalar_toScalar(tmp[3]));
49 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
50 return SkDScalar_toScalar(SkDScalar_setMul(ax, bx) +
51 SkDScalar_setMul(ay, by));
54 bool SkSetPoly3To3_D(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) {
55 const SkPoint& srcAve = src[0];
56 const SkPoint& dstAve = dst[0];
58 SkMatrix srcOP, dstOP;
60 computeOuterProduct(&srcOP, src, srcAve, src, srcAve);
62 if (!srcOP.invert(&srcOP)) {
66 computeOuterProduct(&dstOP, src, srcAve, dst, dstAve);
68 matrix->setConcat(dstOP, srcOP);
69 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY,
70 matrix->getScaleX(), matrix->getSkewX()));
71 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY,
72 matrix->getSkewY(), matrix->getScaleY()));