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 #include "SkMalloc.h" 10 11 // FIXME: needs to be in a header 12 bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]); 13 14 typedef double SkDScalar; 15 16 static SkScalar SkDScalar_toScalar(SkDScalar value) { 17 return static_cast<float>(value); 18 } 19 static SkScalar divide(SkDScalar numer, SkDScalar denom) { 20 return static_cast<float>(numer / denom); 21 } 22 23 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) { 24 return (SkDScalar) ((SkDScalar) a * b); 25 } 26 27 static void computeOuterProduct(SkScalar op[4], 28 const SkPoint pts0[3], const SkPoint& ave0, 29 const SkPoint pts1[3], const SkPoint& ave1) { 30 sk_bzero(op, 4 * sizeof(op[0])); 31 for (int i = 0; i < 3; i++) { 32 SkScalar x0 = pts0[i].fX - ave0.fX; 33 SkScalar y0 = pts0[i].fY - ave0.fY; 34 SkScalar x1 = pts1[i].fX - ave1.fX; 35 SkScalar y1 = pts1[i].fY - ave1.fY; 36 op[0] += x0 * x1; 37 op[1] += x0 * y1; 38 op[2] += y0 * x1; 39 op[3] += y0 * y1; 40 } 41 } 42 43 static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { 44 return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by); 45 } 46 47 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { 48 return SkDScalar_toScalar(ddot(ax, ay, bx, by)); 49 } 50 51 bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) { 52 const SkPoint& srcAve = src[0]; 53 const SkPoint& dstAve = dst[0]; 54 55 SkScalar srcOP[4], dstOP[4]; 56 57 computeOuterProduct(srcOP, src, srcAve, src, srcAve); 58 computeOuterProduct(dstOP, src, srcAve, dst, dstAve); 59 60 SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) - 61 SkDScalar_setMul(srcOP[1], srcOP[2]); 62 63 SkDScalar M[4]; 64 65 const SkScalar srcOP0 = srcOP[3]; 66 const SkScalar srcOP1 = -srcOP[1]; 67 const SkScalar srcOP2 = -srcOP[2]; 68 const SkScalar srcOP3 = srcOP[0]; 69 70 M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]); 71 M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]); 72 M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]); 73 M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]); 74 75 matrix->reset(); 76 matrix->setScaleX(divide(M[0], det)); 77 matrix->setSkewX( divide(M[1], det)); 78 matrix->setSkewY (divide(M[2], det)); 79 matrix->setScaleY(divide(M[3], det)); 80 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY, 81 matrix->getScaleX(), matrix->getSkewX())); 82 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY, 83 matrix->getSkewY(), matrix->getScaleY())); 84 return true; 85 } 86
