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Revert "Add QBezier methods for computing a quadratic curves approximation"

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Were added for 6.6, but turns out they were not quite ready, and also
live better together with the quadpath class in the curve renderer.
This reverts commit aaccd50224.

Pick-to: 6.6
Change-Id: I58399f8e280d5353cb9c3102e8a8e15dcfa4484a
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
This commit is contained in:
Eirik Aavitsland 2023-08-07 10:23:41 +02:00
parent f8f23c43fe
commit 3cc693d256
2 changed files with 0 additions and 106 deletions
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102
src/gui/painting/qbezier.cpp
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@ -134,108 +134,6 @@ void QBezier::addToPolygon(QDataBuffer<QPointF> &polygon, qreal bezier_flattenin
}
}
QPolygonF QBezier::toQuadratics(qreal errorLimit) const
{
qreal infPoints[2];
int numInfPoints = inflectionPoints(infPoints);
QPolygonF res;
res.reserve((numInfPoints + 1) * 3 * 2);
res.append(pt1());
qreal t0 = 0;
for (int i = 0; i < numInfPoints + 1; i++) { // #segments == #inflectionpoints + 1
qreal t1 = (i < numInfPoints) ? infPoints[i] : 1;
QBezier segment = bezierOnInterval(t0, t1);
segment.addToQuadratics(&res, t1 - t0, errorLimit);
t0 = t1;
}
return res;
}
static inline qreal scoreQuadratic(const QBezier &b, QPointF qcp)
{
// Construct a cubic from the quadratic, and compare its control points to the originals'
const QRectF bounds = b.bounds();
qreal dim = QLineF(bounds.topLeft(), bounds.bottomRight()).length();
if (qFuzzyIsNull(dim))
return 1;
const qreal f = 2.0 / 3;
const QPointF cp1 = b.pt1() + f * (qcp - b.pt1());
const QPointF cp2 = b.pt4() + f * (qcp - b.pt4());
const QLineF d1(b.pt2(), cp1);
const QLineF d2(b.pt3(), cp2);
return qMax(d1.length(), d2.length()) / dim;
}
static inline QPointF quadraticForCubic(const QBezier &b)
{
QPointF qcp;
const QLineF st = b.startTangent();
const QLineF et = b.endTangent();
if (st.intersects(et, &qcp) == QLineF::NoIntersection)
qcp = b.midPoint();
return qcp;
}
void QBezier::addToQuadratics(QPolygonF *p, qreal tspan, qreal errorLimit) const
{
Q_ASSERT((tspan > 0) && !(tspan > 1));
static constexpr qreal MinimumTSpan = 0.1;
QPointF qcp = quadraticForCubic(*this);
if (tspan < MinimumTSpan || scoreQuadratic(*this, qcp) < errorLimit) {
p->append(qcp);
p->append(pt4());
} else {
std::pair<QBezier, QBezier> halves = split();
halves.first.addToQuadratics(p, tspan / 2, errorLimit);
halves.second.addToQuadratics(p, tspan / 2, errorLimit);
}
}
int QBezier::inflectionPoints(qreal *tpoints) const
{
auto isValidRoot = [](qreal r) {
return qIsFinite(r) && (r > 0) && (!qFuzzyIsNull(float(r))) && (r < 1)
&& (!qFuzzyIsNull(float(r - 1)));
};
// normalize so pt1.x,pt1.y,pt4.y == 0
QTransform xf;
const QLineF l(pt1(), pt4());
xf.rotate(l.angle());
xf.translate(-pt1().x(), -pt1().y());
const QBezier n = mapBy(xf);
Q_ASSERT(n.pt1() == QPoint() && qFuzzyIsNull(float(n.pt4().y())));
const qreal p = n.pt3().x() * n.pt2().y();
const qreal q = n.pt4().x() * n.pt2().y();
const qreal r = n.pt2().x() * n.pt3().y();
const qreal s = n.pt4().x() * n.pt3().y();
const qreal a = 36 * ((-3 * p) + (2 * q) + (3 * r) - s);
if (!a)
return 0;
const qreal b = -18 * (((3 * p) - q) - (3 * r));
const qreal c = 18 * (r - p);
const qreal rad = (b * b) - (2 * a * c);
if (rad < 0)
return 0;
const qreal sqr = qSqrt(rad);
const qreal root1 = (b + sqr) / a;
const qreal root2 = (b - sqr) / a;
int res = 0;
if (isValidRoot(root1))
tpoints[res++] = root1;
if (!qFuzzyCompare(root2, root1) && isValidRoot(root2))
tpoints[res++] = root2;
if (res == 2 && tpoints[0] > tpoints[1])
qSwap(tpoints[0], tpoints[1]);
return res;
}
QRectF QBezier::bounds() const
{
qreal xmin = x1;

4
src/gui/painting/qbezier_p.h
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@ -47,10 +47,6 @@ public:
void addToPolygon(QPolygonF *p, qreal bezier_flattening_threshold = 0.5) const;
void addToPolygon(QDataBuffer<QPointF> &polygon, qreal bezier_flattening_threshold) const;
QPolygonF toQuadratics(qreal errorLimit = 0.2) const;
void addToQuadratics(QPolygonF *p, qreal tspan = 1.0, qreal errorLimit = 0.2) const;
int inflectionPoints(qreal *tpoints) const;
QRectF bounds() const;
qreal length(qreal error = 0.01) const;
void addIfClose(qreal *length, qreal error) const;