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_D(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]); 13 14 typedef int64_t SkDScalar; 15 16 static SkScalar SkDScalar_toScalar(SkDScalar value) { 17 SkDScalar result = (value + (1 << 15)) >> 16; 18 SkDEBUGCODE(int top = static_cast<int>(result >> 31);) 19 SkASSERT(top == 0 || top == -1); 20 return (SkScalar)result; 21 } 22 23 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) { 24 return (SkDScalar) ((SkDScalar) a * (SkDScalar) b); 25 } 26 27 static void computeOuterProduct(SkMatrix* matrix, 28 const SkPoint pts0[3], const SkPoint& ave0, 29 const SkPoint pts1[3], const SkPoint& ave1) { 30 SkDScalar tmp[4]; 31 sk_bzero(tmp, sizeof(tmp)); 32 33 for (int i = 0; i < 3; i++) { 34 SkScalar x0 = pts0[i].fX - ave0.fX; 35 SkScalar y0 = pts0[i].fY - ave0.fY; 36 SkScalar x1 = pts1[i].fX - ave1.fX; 37 SkScalar y1 = pts1[i].fY - ave1.fY; 38 tmp[0] += SkDScalar_setMul(x0, x1); 39 tmp[1] += SkDScalar_setMul(x0, y1); 40 tmp[2] += SkDScalar_setMul(y0, x1); 41 tmp[3] += SkDScalar_setMul(y0, y1); 42 } 43 matrix->reset(); 44 matrix->setScaleX(SkDScalar_toScalar(tmp[0])); 45 matrix->setSkewY( SkDScalar_toScalar(tmp[1])); 46 matrix->setSkewX( SkDScalar_toScalar(tmp[2])); 47 matrix->setScaleY(SkDScalar_toScalar(tmp[3])); 48 } 49 50 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { 51 return SkDScalar_toScalar(SkDScalar_setMul(ax, bx) + 52 SkDScalar_setMul(ay, by)); 53 } 54 55 bool SkSetPoly3To3_D(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) { 56 const SkPoint& srcAve = src[0]; 57 const SkPoint& dstAve = dst[0]; 58 59 SkMatrix srcOP, dstOP; 60 61 computeOuterProduct(&srcOP, src, srcAve, src, srcAve); 62 63 if (!srcOP.invert(&srcOP)) { 64 return false; 65 } 66 67 computeOuterProduct(&dstOP, src, srcAve, dst, dstAve); 68 69 matrix->setConcat(dstOP, srcOP); 70 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY, 71 matrix->getScaleX(), matrix->getSkewX())); 72 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY, 73 matrix->getSkewY(), matrix->getScaleY())); 74 return true; 75 } 76
