66 lines
2.1 KiB
C++
66 lines
2.1 KiB
C++
#include "SkMatrix.h"
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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 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(SkMatrix* matrix,
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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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SkDScalar tmp[4];
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bzero(tmp, sizeof(tmp));
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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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tmp[0] += SkDScalar_setMul(x0, x1);
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tmp[1] += SkDScalar_setMul(x0, y1);
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tmp[2] += SkDScalar_setMul(y0, x1);
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tmp[3] += SkDScalar_setMul(y0, y1);
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}
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matrix->reset();
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matrix->setScaleX(SkDScalar_toScalar(tmp[0]));
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matrix->setSkewY( SkDScalar_toScalar(tmp[1]));
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matrix->setSkewX( SkDScalar_toScalar(tmp[2]));
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matrix->setScaleY(SkDScalar_toScalar(tmp[3]));
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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(SkDScalar_setMul(ax, bx) +
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SkDScalar_setMul(ay, 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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SkMatrix srcOP, dstOP;
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computeOuterProduct(&srcOP, src, srcAve, src, srcAve);
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if (!srcOP.invert(&srcOP)) {
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return false;
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}
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computeOuterProduct(&dstOP, src, srcAve, dst, dstAve);
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matrix->setConcat(dstOP, srcOP);
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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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