diff options
Diffstat (limited to 'src/gui/painting/qbezier.cpp')
| -rw-r--r-- | src/gui/painting/qbezier.cpp | 228 |
1 files changed, 4 insertions, 224 deletions
diff --git a/src/gui/painting/qbezier.cpp b/src/gui/painting/qbezier.cpp index 7ff2a37a58..2a9b31a549 100644 --- a/src/gui/painting/qbezier.cpp +++ b/src/gui/painting/qbezier.cpp @@ -93,7 +93,7 @@ QBezier QBezier::fromPoints(const QPointF &p1, const QPointF &p2, /*! \internal */ -QPolygonF QBezier::toPolygon() const +QPolygonF QBezier::toPolygon(qreal bezier_flattening_threshold) const { // flattening is done by splitting the bezier until we can replace the segment by a straight // line. We split further until the control points are close enough to the line connecting the @@ -108,7 +108,7 @@ QPolygonF QBezier::toPolygon() const QPolygonF polygon; polygon.append(QPointF(x1, y1)); - addToPolygon(&polygon); + addToPolygon(&polygon, bezier_flattening_threshold); return polygon; } @@ -117,34 +117,6 @@ QBezier QBezier::mapBy(const QTransform &transform) const return QBezier::fromPoints(transform.map(pt1()), transform.map(pt2()), transform.map(pt3()), transform.map(pt4())); } -//0.05 is really low, but required for scaled-up beziers... -static const qreal flatness = 0.05; - -//based on "Fast, precise flattening of cubic Bezier path and offset curves" -// by T. F. Hain, A. L. Ahmad, S. V. R. Racherla and D. D. Langan -static inline void flattenBezierWithoutInflections(QBezier &bez, - QPolygonF *&p) -{ - QBezier left; - - while (1) { - qreal dx = bez.x2 - bez.x1; - qreal dy = bez.y2 - bez.y1; - - qreal normalized = qSqrt(dx * dx + dy * dy); - if (qFuzzyIsNull(normalized)) - break; - - qreal d = qAbs(dx * (bez.y3 - bez.y2) - dy * (bez.x3 - bez.x2)); - - qreal t = qSqrt(4. / 3. * normalized * flatness / d); - if (t > 1 || qFuzzyIsNull(t - (qreal)1.)) - break; - bez.parameterSplitLeft(t, &left); - p->append(bez.pt1()); - } -} - QBezier QBezier::getSubRange(qreal t0, qreal t1) const { QBezier result; @@ -223,7 +195,7 @@ static inline bool findInflections(qreal a, qreal b, qreal c, } -void QBezier::addToPolygon(QPolygonF *polygon) const +void QBezier::addToPolygon(QPolygonF *polygon, qreal bezier_flattening_threshold) const { QBezier beziers[32]; beziers[0] = *this; @@ -243,7 +215,7 @@ void QBezier::addToPolygon(QPolygonF *polygon) const qAbs(b->x1 - b->x3) + qAbs(b->y1 - b->y3); l = 1.; } - if (d < flatness*l || b == beziers + 31) { + 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; @@ -255,55 +227,6 @@ void QBezier::addToPolygon(QPolygonF *polygon) const } } -void QBezier::addToPolygonMixed(QPolygonF *polygon) const -{ - qreal ax = -x1 + 3*x2 - 3*x3 + x4; - qreal ay = -y1 + 3*y2 - 3*y3 + y4; - qreal bx = 3*x1 - 6*x2 + 3*x3; - qreal by = 3*y1 - 6*y2 + 3*y3; - qreal cx = -3*x1 + 3*x2; - qreal cy = -3*y1 + 2*y2; - qreal a = 6 * (ay * bx - ax * by); - qreal b = 6 * (ay * cx - ax * cy); - qreal c = 2 * (by * cx - bx * cy); - - if ((qFuzzyIsNull(a) && qFuzzyIsNull(b)) || - (b * b - 4 * a *c) < 0) { - QBezier bez(*this); - flattenBezierWithoutInflections(bez, polygon); - polygon->append(QPointF(x4, y4)); - } else { - 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 < .5*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; - } - } - } -} - QRectF QBezier::bounds() const { qreal xmin = x1; @@ -824,147 +747,4 @@ QBezier QBezier::bezierOnInterval(qreal t0, qreal t1) const return result; } - -static inline void bindInflectionPoint(const QBezier &bez, const qreal t, - qreal *tMinus , qreal *tPlus) -{ - if (t <= 0) { - *tMinus = *tPlus = -1; - return; - } else if (t >= 1) { - *tMinus = *tPlus = 2; - return; - } - - QBezier left, right; - splitBezierAt(bez, t, &left, &right); - - qreal ax = -right.x1 + 3*right.x2 - 3*right.x3 + right.x4; - qreal ay = -right.y1 + 3*right.y2 - 3*right.y3 + right.y4; - qreal ex = 3 * (right.x2 - right.x3); - qreal ey = 3 * (right.y2 - right.y3); - - qreal s4 = qAbs(6 * (ey * ax - ex * ay) / qSqrt(ex * ex + ey * ey)) + 0.00001f; - qreal tf = qPow(qreal(9 * flatness / s4), qreal(1./3.)); - *tMinus = t - (1 - t) * tf; - *tPlus = t + (1 - t) * tf; -} - -void QBezier::addToPolygonIterative(QPolygonF *p) const -{ - qreal t1, t2, tcusp; - qreal t1min, t1plus, t2min, t2plus; - - qreal ax = -x1 + 3*x2 - 3*x3 + x4; - qreal ay = -y1 + 3*y2 - 3*y3 + y4; - qreal bx = 3*x1 - 6*x2 + 3*x3; - qreal by = 3*y1 - 6*y2 + 3*y3; - qreal cx = -3*x1 + 3*x2; - qreal cy = -3*y1 + 2*y2; - - if (findInflections(6 * (ay * bx - ax * by), - 6 * (ay * cx - ax * cy), - 2 * (by * cx - bx * cy), - &t1, &t2, &tcusp)) { - bindInflectionPoint(*this, t1, &t1min, &t1plus); - bindInflectionPoint(*this, t2, &t2min, &t2plus); - - QBezier tmpBez = *this; - QBezier left, right, bez1, bez2, bez3; - if (t1min > 0) { - if (t1min >= 1) { - flattenBezierWithoutInflections(tmpBez, p); - } else { - splitBezierAt(tmpBez, t1min, &left, &right); - flattenBezierWithoutInflections(left, p); - p->append(tmpBez.pointAt(t1min)); - - if (t2min < t1plus) { - if (tcusp < 1) { - p->append(tmpBez.pointAt(tcusp)); - } - if (t2plus < 1) { - splitBezierAt(tmpBez, t2plus, &left, &right); - flattenBezierWithoutInflections(right, p); - } - } else if (t1plus < 1) { - if (t2min < 1) { - splitBezierAt(tmpBez, t2min, &bez3, &right); - splitBezierAt(bez3, t1plus, &left, &bez2); - - flattenBezierWithoutInflections(bez2, p); - p->append(tmpBez.pointAt(t2min)); - - if (t2plus < 1) { - splitBezierAt(tmpBez, t2plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } else { - splitBezierAt(tmpBez, t1plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } - } - } else if (t1plus > 0) { - p->append(QPointF(x1, y1)); - if (t2min < t1plus) { - if (tcusp < 1) { - p->append(tmpBez.pointAt(tcusp)); - } - if (t2plus < 1) { - splitBezierAt(tmpBez, t2plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } else if (t1plus < 1) { - if (t2min < 1) { - splitBezierAt(tmpBez, t2min, &bez3, &right); - splitBezierAt(bez3, t1plus, &left, &bez2); - - flattenBezierWithoutInflections(bez2, p); - - p->append(tmpBez.pointAt(t2min)); - if (t2plus < 1) { - splitBezierAt(tmpBez, t2plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } else { - splitBezierAt(tmpBez, t1plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } - } else if (t2min > 0) { - if (t2min < 1) { - splitBezierAt(tmpBez, t2min, &bez1, &right); - flattenBezierWithoutInflections(bez1, p); - p->append(tmpBez.pointAt(t2min)); - - if (t2plus < 1) { - splitBezierAt(tmpBez, t2plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } else { - //### in here we should check whether the area of the - // triangle formed between pt1/pt2/pt3 is smaller - // or equal to 0 and then do iterative flattening - // if not we should fallback and do the recursive - // flattening. - flattenBezierWithoutInflections(tmpBez, p); - } - } else if (t2plus > 0) { - p->append(QPointF(x1, y1)); - if (t2plus < 1) { - splitBezierAt(tmpBez, t2plus, &left, &bez2); - flattenBezierWithoutInflections(bez2, p); - } - } else { - flattenBezierWithoutInflections(tmpBez, p); - } - } else { - QBezier bez = *this; - flattenBezierWithoutInflections(bez, p); - } - - p->append(QPointF(x4, y4)); -} - QT_END_NAMESPACE |