1 2 /* 3 * Copyright 2011 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 #include "SkMatrix.h" 9 10 // FIXME: needs to be in a header 11 bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]); 12 13 typedef double SkDScalar; 14 15 static SkScalar SkDScalar_toScalar(SkDScalar value) { 16 return static_cast<float>(value); 17 } 18 static SkScalar divide(SkDScalar numer, SkDScalar denom) { 19 return static_cast<float>(numer / denom); 20 } 21 22 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) { 23 return (SkDScalar) ((SkDScalar) a * b); 24 } 25 26 static void computeOuterProduct(SkScalar op[4], 27 const SkPoint pts0[3], const SkPoint& ave0, 28 const SkPoint pts1[3], const SkPoint& ave1) { 29 sk_bzero(op, 4 * sizeof(op[0])); 30 for (int i = 0; i < 3; i++) { 31 SkScalar x0 = pts0[i].fX - ave0.fX; 32 SkScalar y0 = pts0[i].fY - ave0.fY; 33 SkScalar x1 = pts1[i].fX - ave1.fX; 34 SkScalar y1 = pts1[i].fY - ave1.fY; 35 op[0] += SkScalarMul(x0, x1); 36 op[1] += SkScalarMul(x0, y1); 37 op[2] += SkScalarMul(y0, x1); 38 op[3] += SkScalarMul(y0, y1); 39 } 40 } 41 42 static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { 43 return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by); 44 } 45 46 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { 47 return SkDScalar_toScalar(ddot(ax, ay, bx, by)); 48 } 49 50 bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) { 51 const SkPoint& srcAve = src[0]; 52 const SkPoint& dstAve = dst[0]; 53 54 SkScalar srcOP[4], dstOP[4]; 55 56 computeOuterProduct(srcOP, src, srcAve, src, srcAve); 57 computeOuterProduct(dstOP, src, srcAve, dst, dstAve); 58 59 SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) - 60 SkDScalar_setMul(srcOP[1], srcOP[2]); 61 62 SkDScalar M[4]; 63 64 const SkScalar srcOP0 = srcOP[3]; 65 const SkScalar srcOP1 = -srcOP[1]; 66 const SkScalar srcOP2 = -srcOP[2]; 67 const SkScalar srcOP3 = srcOP[0]; 68 69 M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]); 70 M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]); 71 M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]); 72 M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]); 73 74 matrix->reset(); 75 matrix->setScaleX(divide(M[0], det)); 76 matrix->setSkewX( divide(M[1], det)); 77 matrix->setSkewY (divide(M[2], det)); 78 matrix->setScaleY(divide(M[3], det)); 79 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY, 80 matrix->getScaleX(), matrix->getSkewX())); 81 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY, 82 matrix->getSkewY(), matrix->getScaleY())); 83 return true; 84 } 85
