| |
| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| #include "SkMatrix.h" |
| |
| // FIXME: needs to be in a header |
| bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]); |
| |
| typedef double SkDScalar; |
| |
| static SkScalar SkDScalar_toScalar(SkDScalar value) { |
| return static_cast<float>(value); |
| } |
| static SkScalar divide(SkDScalar numer, SkDScalar denom) { |
| return static_cast<float>(numer / denom); |
| } |
| |
| static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) { |
| return (SkDScalar) ((SkDScalar) a * b); |
| } |
| |
| static void computeOuterProduct(SkScalar op[4], |
| const SkPoint pts0[3], const SkPoint& ave0, |
| const SkPoint pts1[3], const SkPoint& ave1) { |
| sk_bzero(op, 4 * sizeof(op[0])); |
| for (int i = 0; i < 3; i++) { |
| SkScalar x0 = pts0[i].fX - ave0.fX; |
| SkScalar y0 = pts0[i].fY - ave0.fY; |
| SkScalar x1 = pts1[i].fX - ave1.fX; |
| SkScalar y1 = pts1[i].fY - ave1.fY; |
| op[0] += SkScalarMul(x0, x1); |
| op[1] += SkScalarMul(x0, y1); |
| op[2] += SkScalarMul(y0, x1); |
| op[3] += SkScalarMul(y0, y1); |
| } |
| } |
| |
| static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { |
| return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by); |
| } |
| |
| static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) { |
| return SkDScalar_toScalar(ddot(ax, ay, bx, by)); |
| } |
| |
| bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) { |
| const SkPoint& srcAve = src[0]; |
| const SkPoint& dstAve = dst[0]; |
| |
| SkScalar srcOP[4], dstOP[4]; |
| |
| computeOuterProduct(srcOP, src, srcAve, src, srcAve); |
| computeOuterProduct(dstOP, src, srcAve, dst, dstAve); |
| |
| SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) - |
| SkDScalar_setMul(srcOP[1], srcOP[2]); |
| |
| SkDScalar M[4]; |
| |
| const SkScalar srcOP0 = srcOP[3]; |
| const SkScalar srcOP1 = -srcOP[1]; |
| const SkScalar srcOP2 = -srcOP[2]; |
| const SkScalar srcOP3 = srcOP[0]; |
| |
| M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]); |
| M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]); |
| M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]); |
| M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]); |
| |
| matrix->reset(); |
| matrix->setScaleX(divide(M[0], det)); |
| matrix->setSkewX( divide(M[1], det)); |
| matrix->setSkewY (divide(M[2], det)); |
| matrix->setScaleY(divide(M[3], det)); |
| matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY, |
| matrix->getScaleX(), matrix->getSkewX())); |
| matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY, |
| matrix->getSkewY(), matrix->getScaleY())); |
| return true; |
| } |