void QBezier::addToPolygon(QPolygonF *polygon, qreal bezier_flattening_threshold) const
{
QBezier beziers[32];
beziers[0] = *this;
QBezier *b = beziers;
while (b >= beziers) {
// check if we can pop the top bezier curve from the stack
qreal y4y1 = b->y4 - b->y1;
qreal x4x1 = b->x4 - b->x1;
qreal l = qAbs(x4x1) + qAbs(y4y1);
qreal d;
if (l > 1.) {
d = qAbs( (x4x1)*(b->y1 - b->y2) - (y4y1)*(b->x1 - b->x2) )
+ qAbs( (x4x1)*(b->y1 - b->y3) - (y4y1)*(b->x1 - b->x3) );
} else {
d = qAbs(b->x1 - b->x2) + qAbs(b->y1 - b->y2) +
qAbs(b->x1 - b->x3) + qAbs(b->y1 - b->y3);
l = 1.;
}
if (d < bezier_flattening_threshold*l || b == beziers + 31) {
// good enough, we pop it off and add the endpoint
polygon->append(QPointF(b->x4, b->y4));
--b;
} else {
// split, second half of the polygon goes lower into the stack
b->split(b+1, b);
++b;
}
}
}
int QBezier::shifted(QBezier *curveSegments, int maxSegments, qreal offset, float threshold) const
{
Q_ASSERT(curveSegments);
Q_ASSERT(maxSegments > 0);
if (x1 == x2 && x1 == x3 && x1 == x4 &&
y1 == y2 && y1 == y3 && y1 == y4)
return 0;
--maxSegments;
QBezier beziers[10];
redo:
beziers[0] = *this;
QBezier *b = beziers;
QBezier *o = curveSegments;
while (b >= beziers) {
int stack_segments = b - beziers + 1;
if ((stack_segments == 10) || (o - curveSegments == maxSegments - stack_segments)) {
threshold *= qreal(1.5);
if (threshold > qreal(2.0))
goto give_up;
goto redo;
}
ShiftResult res = shift(b, o, offset, threshold);
if (res == Discard) {
--b;
} else if (res == Ok) {
++o;
--b;
continue;
} else if (res == Circle && maxSegments - (o - curveSegments) >= 2) {
// add semi circle
if (addCircle(b, offset, o))
o += 2;
--b;
} else {
b->split(b+1, b);
++b;
}
}
give_up:
while (b >= beziers) {
ShiftResult res = shift(b, o, offset, threshold);
// if res isn't Ok or Split then *o is undefined
if (res == Ok || res == Split)
++o;
--b;
}
Q_ASSERT(o - curveSegments <= maxSegments);
return o - curveSegments;
}
void QBezier::addToPolygon(QDataBuffer<QPointF> &polygon, qreal bezier_flattening_threshold) const
{
QBezier beziers[10];
int levels[10];
beziers[0] = *this;
levels[0] = 9;
QBezier *b = beziers;
int *lvl = levels;
while (b >= beziers) {
// check if we can pop the top bezier curve from the stack
qreal y4y1 = b->y4 - b->y1;
qreal x4x1 = b->x4 - b->x1;
qreal l = qAbs(x4x1) + qAbs(y4y1);
qreal d;
if (l > 1.) {
d = qAbs( (x4x1)*(b->y1 - b->y2) - (y4y1)*(b->x1 - b->x2) )
+ qAbs( (x4x1)*(b->y1 - b->y3) - (y4y1)*(b->x1 - b->x3) );
} else {
d = qAbs(b->x1 - b->x2) + qAbs(b->y1 - b->y2) +
qAbs(b->x1 - b->x3) + qAbs(b->y1 - b->y3);
l = 1.;
}
if (d < bezier_flattening_threshold*l || *lvl == 0) {
// good enough, we pop it off and add the endpoint
polygon.add(QPointF(b->x4, b->y4));
--b;
--lvl;
} else {
// split, second half of the polygon goes lower into the stack
b->split(b+1, b);
lvl[1] = --lvl[0];
++b;
++lvl;
}
}
}
