525644095b
git-svn-id: http://skia.googlecode.com/svn/trunk@1925 2bbb7eff-a529-9590-31e7-b0007b416f81
91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
#include "SkMatrix.h"
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#ifdef SK_SCALAR_IS_FIXED
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typedef int64_t SkDScalar;
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static SkScalar SkDScalar_toScalar(SkDScalar value) {
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SkDScalar result = (value + (1 << 15)) >> 16;
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int top = result >> 31;
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SkASSERT(top == 0 || top == -1);
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return (SkScalar)result;
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}
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static SkScalar divide(SkDScalar numer, SkDScalar denom) {
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denom >>= 16;
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return numer / denom;
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}
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#else
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typedef double SkDScalar;
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static SkScalar SkDScalar_toScalar(SkDScalar value) {
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return static_cast<float>(value);
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}
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static SkScalar divide(SkDScalar numer, SkDScalar denom) {
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return static_cast<float>(numer / denom);
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}
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#endif
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static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
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return (SkDScalar)a * b;
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}
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static void computeOuterProduct(SkScalar op[4],
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const SkPoint pts0[3], const SkPoint& ave0,
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const SkPoint pts1[3], const SkPoint& ave1) {
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sk_bzero(op, 4 * sizeof(op[0]));
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for (int i = 0; i < 3; i++) {
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SkScalar x0 = pts0[i].fX - ave0.fX;
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SkScalar y0 = pts0[i].fY - ave0.fY;
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SkScalar x1 = pts1[i].fX - ave1.fX;
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SkScalar y1 = pts1[i].fY - ave1.fY;
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op[0] += SkScalarMul(x0, x1);
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op[1] += SkScalarMul(x0, y1);
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op[2] += SkScalarMul(y0, x1);
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op[3] += SkScalarMul(y0, y1);
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}
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}
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static SkDScalar ddot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
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return SkDScalar_setMul(ax, bx) + SkDScalar_setMul(ay, by);
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}
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static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
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return SkDScalar_toScalar(ddot(ax, ay, bx, by));
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}
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bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) {
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const SkPoint& srcAve = src[0];
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const SkPoint& dstAve = dst[0];
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SkScalar srcOP[4], dstOP[4];
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computeOuterProduct(srcOP, src, srcAve, src, srcAve);
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computeOuterProduct(dstOP, src, srcAve, dst, dstAve);
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SkDScalar det = SkDScalar_setMul(srcOP[0], srcOP[3]) -
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SkDScalar_setMul(srcOP[1], srcOP[2]);
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SkDScalar M[4];
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const SkScalar srcOP0 = srcOP[3];
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const SkScalar srcOP1 = -srcOP[1];
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const SkScalar srcOP2 = -srcOP[2];
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const SkScalar srcOP3 = srcOP[0];
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M[0] = ddot(srcOP0, srcOP1, dstOP[0], dstOP[2]);
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M[1] = ddot(srcOP2, srcOP3, dstOP[0], dstOP[2]);
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M[2] = ddot(srcOP0, srcOP1, dstOP[1], dstOP[3]);
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M[3] = ddot(srcOP2, srcOP3, dstOP[1], dstOP[3]);
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matrix->reset();
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matrix->setScaleX(divide(M[0], det));
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matrix->setSkewX( divide(M[1], det));
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matrix->setSkewY (divide(M[2], det));
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matrix->setScaleY(divide(M[3], det));
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matrix->setTranslateX(dstAve.fX - dot(srcAve.fX, srcAve.fY,
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matrix->getScaleX(), matrix->getSkewX()));
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matrix->setTranslateY(dstAve.fY - dot(srcAve.fX, srcAve.fY,
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matrix->getSkewY(), matrix->getScaleY()));
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return true;
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}
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