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#include "SkMatrix.h"
typedef int64_t SkDScalar;
static SkScalar SkDScalar_toScalar(SkDScalar value) {
SkDScalar result = (value + (1 << 15)) >> 16;
int top = result >> 31;
SkASSERT(top == 0 || top == -1);
return (SkScalar)result;
}
static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
return (SkDScalar)a * b;
}
static void computeOuterProduct(SkMatrix* matrix,
const SkPoint pts0[3], const SkPoint& ave0,
const SkPoint pts1[3], const SkPoint& ave1) {
SkDScalar tmp[4];
bzero(tmp, sizeof(tmp));
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;
tmp[0] += SkDScalar_setMul(x0, x1);
tmp[1] += SkDScalar_setMul(x0, y1);
tmp[2] += SkDScalar_setMul(y0, x1);
tmp[3] += SkDScalar_setMul(y0, y1);
}
matrix->reset();
matrix->setScaleX(SkDScalar_toScalar(tmp[0]));
matrix->setSkewY( SkDScalar_toScalar(tmp[1]));
matrix->setSkewX( SkDScalar_toScalar(tmp[2]));
matrix->setScaleY(SkDScalar_toScalar(tmp[3]));
}
static SkScalar dot(SkScalar ax, SkScalar ay, SkScalar bx, SkScalar by) {
return SkDScalar_toScalar(SkDScalar_setMul(ax, bx) +
SkDScalar_setMul(ay, by));
}
bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]) {
const SkPoint& srcAve = src[0];
const SkPoint& dstAve = dst[0];
SkMatrix srcOP, dstOP;
computeOuterProduct(&srcOP, src, srcAve, src, srcAve);
if (!srcOP.invert(&srcOP)) {
return false;
}
computeOuterProduct(&dstOP, src, srcAve, dst, dstAve);
matrix->setConcat(dstOP, srcOP);
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;
}
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