void CanvasCairo::pathAltArcTo(float rx, float ry, float angle, bool largeArc, bool sweep, float x, float y) {
double _x, _y;
cairo_get_current_point (_context, &_x, &_y);
rx = fabsf(rx); ry = fabsf(ry);
Mat4 transform(Mat4::IDENTITY); Mat4::createRotationZ(angle, &transform);
Mat4 inverse = transform; inverse.transpose();
Vec2 vDash(cocos2d::PointApplyTransform(Vec2((_x - x) / 2, (_y - y) / 2), inverse));
float lambda = (vDash.x * vDash.x) / (rx * rx) + (vDash.y * vDash.y) / (ry * ry);
if (lambda > 1.0f) {
rx = sqrtf(lambda) * rx; ry = sqrtf(lambda) * ry;
vDash = Vec2(cocos2d::PointApplyTransform(Vec2((_x - x) / 2, (_y - y) / 2), inverse));
}
float rx_y1_ = (rx * rx * vDash.y * vDash.y);
float ry_x1_ = (ry * ry * vDash.x * vDash.x);
float cst = sqrtf(((rx * rx * ry * ry) - rx_y1_ - ry_x1_) / (rx_y1_ + ry_x1_));
Vec2 cDash((largeArc != sweep ? 1.0f : -1.0f) * cst * rx * vDash.y / ry,
(largeArc != sweep ? 1.0f : -1.0f) * - cst * ry * vDash.x / rx);
float cx = cDash.x + (_x + x) / 2;
float cy = cDash.y + (_y + y) / 2;
float startAngle = Vec2::angle(Vec2(1.0f, 0.0f), Vec2((vDash.x - cDash.x) / rx, (vDash.y - cDash.y) / ry));
float sweepAngle = Vec2::angle(Vec2((vDash.x - cDash.x) / rx, (vDash.y - cDash.y) / ry),
Vec2((-vDash.x - cDash.x) / rx, (-vDash.y - cDash.y) / ry));
pathArcTo(cx, cy, rx, ry, startAngle, sweepAngle, angle);
}
// Draw a "spiral" arc defined by circle arcs around a center, a start and an end radius
void spiralArcTo( QPainterPath& path, const QPointF& center, qreal startAngle, qreal startRadius, qreal endAngle, qreal endRadius, int direction )
{
// start point
QPointF A = circlePoint( center, startRadius, startAngle );
// end point
QPointF B = circlePoint( center, endRadius, endAngle );
// middle points
qreal deltaAngle;
deltaAngle = endAngle - startAngle;
if ( direction * deltaAngle < 0.0 )
deltaAngle = deltaAngle + direction * 2 * M_PI;
QPointF I1 = circlePoint( center, 0.75 * startRadius + 0.25 * endRadius, startAngle + 0.25 * deltaAngle );
QPointF I2 = circlePoint( center, 0.50 * startRadius + 0.50 * endRadius, startAngle + 0.50 * deltaAngle );
QPointF I3 = circlePoint( center, 0.25 * startRadius + 0.75 * endRadius, startAngle + 0.75 * deltaAngle );
qreal cRadius;
QPointF cCenter;
// first circle arc
if ( ! pointsToCircle( A, I1, I2, cCenter, cRadius ) )
{
// aligned points => draw a straight line
path.lineTo( I2 );
}
else
{
// angles in the new circle
qreal a1 = atan2( cCenter.y() - A.y(), A.x() - cCenter.x() );
qreal a2 = atan2( cCenter.y() - I2.y(), I2.x() - cCenter.x() );
pathArcTo( path, cCenter, cRadius, a1, a2, direction );
}
// second circle arc
if ( ! pointsToCircle( I2, I3, B, cCenter, cRadius ) )
{
// aligned points => draw a straight line
path.lineTo( B );
}
else
{
// angles in the new circle
qreal a1 = atan2( cCenter.y() - I2.y(), I2.x() - cCenter.x() );
qreal a2 = atan2( cCenter.y() - B.y(), B.x() - cCenter.x() );
pathArcTo( path, cCenter, cRadius, a1, a2, direction );
}
}
QPolygonF curvedArrow( QPointF po, QPointF pm, QPointF pd, qreal startWidth, qreal width, qreal headSize, QgsArrowSymbolLayer::HeadType headType, qreal offset )
{
qreal circleRadius;
QPointF circleCenter;
if ( ! pointsToCircle( po, pm, pd, circleCenter, circleRadius ) || circleRadius > 10000.0 )
{
// aligned points => draw a straight arrow
return straightArrow( po, pd, startWidth, width, headSize, headType, offset );
}
// angles of each point
qreal angle_o = clampAngle( atan2( circleCenter.y() - po.y(), po.x() - circleCenter.x() ) );
qreal angle_m = clampAngle( atan2( circleCenter.y() - pm.y(), pm.x() - circleCenter.x() ) );
qreal angle_d = clampAngle( atan2( circleCenter.y() - pd.y(), pd.x() - circleCenter.x() ) );
// arc direction : 1 = counter-clockwise, -1 = clockwise
int direction = clampAngle( angle_m - angle_o ) < clampAngle( angle_m - angle_d ) ? 1 : -1;
qreal deltaAngle = angle_d - angle_o;
if ( direction * deltaAngle < 0.0 )
deltaAngle = deltaAngle + direction * 2 * M_PI;
qreal length = euclidian_distance( po, pd );
// for close points and deltaAngle < 180, draw a straight line
if ( fabs( deltaAngle ) < M_PI && ((( headType == QgsArrowSymbolLayer::HeadSingle ) && ( length < headSize ) ) ||
(( headType == QgsArrowSymbolLayer::HeadReversed ) && ( length < headSize ) ) ||
(( headType == QgsArrowSymbolLayer::HeadDouble ) && ( length < 2*headSize ) ) ) )
{
return straightArrow( po, pd, startWidth, width, headSize, headType, offset );
}
// ajust coordinates to include offset
circleRadius += offset;
po = circlePoint( circleCenter, circleRadius, angle_o );
pm = circlePoint( circleCenter, circleRadius, angle_m );
pd = circlePoint( circleCenter, circleRadius, angle_d );
qreal headAngle = direction * atan( headSize / circleRadius );
QPainterPath path;
if ( headType == QgsArrowSymbolLayer::HeadDouble )
{
// the first head
path.moveTo( po );
path.lineTo( circlePoint( circleCenter, circleRadius + direction * headSize, angle_o + headAngle ) );
pathArcTo( path, circleCenter, circleRadius + direction * width / 2, angle_o + headAngle, angle_d - headAngle, direction );
// the second head
path.lineTo( circlePoint( circleCenter, circleRadius + direction * headSize, angle_d - headAngle ) );
path.lineTo( pd );
path.lineTo( circlePoint( circleCenter, circleRadius - direction * headSize, angle_d - headAngle ) );
pathArcTo( path, circleCenter, circleRadius - direction * width / 2, angle_d - headAngle, angle_o + headAngle, -direction );
// the end of the first head
path.lineTo( circlePoint( circleCenter, circleRadius - direction * headSize, angle_o + headAngle ) );
path.lineTo( po );
}
else if ( headType == QgsArrowSymbolLayer::HeadSingle )
{
path.moveTo( circlePoint( circleCenter, circleRadius + direction * startWidth / 2, angle_o ) );
spiralArcTo( path, circleCenter, angle_o, circleRadius + direction * startWidth / 2, angle_d - headAngle, circleRadius + direction * width / 2, direction );
// the arrow head
path.lineTo( circlePoint( circleCenter, circleRadius + direction * headSize, angle_d - headAngle ) );
path.lineTo( pd );
path.lineTo( circlePoint( circleCenter, circleRadius - direction * headSize, angle_d - headAngle ) );
spiralArcTo( path, circleCenter, angle_d - headAngle, circleRadius - direction * width / 2, angle_o, circleRadius - direction * startWidth / 2, -direction );
path.lineTo( circlePoint( circleCenter, circleRadius + direction * startWidth / 2, angle_o ) );
}
else if ( headType == QgsArrowSymbolLayer::HeadReversed )
{
path.moveTo( circlePoint( circleCenter, circleRadius + direction * width / 2, angle_o + headAngle ) );
spiralArcTo( path, circleCenter, angle_o + headAngle, circleRadius + direction * width / 2, angle_d, circleRadius + direction * startWidth / 2, direction );
path.lineTo( circlePoint( circleCenter, circleRadius - direction * startWidth / 2, angle_d ) );
spiralArcTo( path, circleCenter, angle_d, circleRadius - direction * startWidth / 2, angle_o + headAngle, circleRadius - direction * width / 2, - direction );
path.lineTo( circlePoint( circleCenter, circleRadius - direction * headSize, angle_o + headAngle ) );
path.lineTo( po );
path.lineTo( circlePoint( circleCenter, circleRadius + direction * headSize, angle_o + headAngle ) );
path.lineTo( circlePoint( circleCenter, circleRadius + direction * width / 2, angle_o + headAngle ) );
}
return path.toSubpathPolygons().at( 0 );
}
