1 #include "SkMatrix.h" 2 3 typedef int64_t SkDScalar; 4 5 static SkScalar SkDScalar_toScalar(SkDScalar value) { 6 SkDScalar result = (value + (1 << 15)) >> 16; 7 int top = result >> 31; 8 SkASSERT(top == 0 || top == -1); 9 return (SkScalar)result; 10 } 11 12 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) { 13 return (SkDScalar)a * b; 14 } 15 16 static void computeOuterProduct(SkMatrix* matrix, 17 const SkPoint pts0[3], const SkPoint& ave0, 18 const SkPoint pts1[3], const SkPoint& ave1) { 19 SkDScalar tmp[4]; 20 sk_bzero(tmp, sizeof(tmp)); 21 22 for (int i = 0; i < 3; i++) { 23 SkScalar x0 = pts0[i].fX - ave0.fX; 24 SkScalar y0 = pts0[i].fY - ave0.fY; 25 SkScalar x1 = pts1[i].fX - ave1.fX; 26 SkScalar y1 = pts1[i].fY - ave1.fY; 27 tmp[0] += SkDScalar_setMul(x0, x1); 28 tmp[1] += SkDScalar_setMul(x0, y1); 29 tmp[2] += SkDScalar_setMul(y0, x1); 30 tmp[3] += SkDScalar_setMul(y0, y1); 31 } 32 matrix->reset(); 33 matrix->setScaleX(SkDScalar_toScalar(tmp[0])); 34 matrix->setSkewY( SkDScalar_toScalar(tmp[1])); 35 matrix->setSkewX( SkDScalar_toScalar(tmp[2])); 36 matrix->setScaleY(SkDScalar_toScalar(tmp[3])); 37 } 38 39 static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { 40 return SkDScalar_toScalar(SkDScalar_setMul(ax, bx) + 41 SkDScalar_setMul(ay, by)); 42 } 43 44 bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) { 45 const SkPoint& srcAve = src[0]; 46 const SkPoint& dstAve = dst[0]; 47 48 SkMatrix srcOP, dstOP; 49 50 computeOuterProduct(&srcOP, src, srcAve, src, srcAve); 51 52 if (!srcOP.invert(&srcOP)) { 53 return false; 54 } 55 56 computeOuterProduct(&dstOP, src, srcAve, dst, dstAve); 57 58 matrix->setConcat(dstOP, srcOP); 59 matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY, 60 matrix->getScaleX(), matrix->getSkewX())); 61 matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY, 62 matrix->getSkewY(), matrix->getScaleY())); 63 return true; 64 } 65 66
