void CurveDragPoint::dragged(Geom::Point &new_pos, GdkEventMotion *event)
{
NodeList::iterator second = first.next();
// special cancel handling - retract handles when if the segment was degenerate
if (_is_drag_cancelled(event) && _segment_was_degenerate) {
first->front()->retract();
second->back()->retract();
_pm.update();
return;
}
if (_drag_initiated && !(event->state & GDK_SHIFT_MASK)) {
SnapManager &m = _desktop->namedview->snap_manager;
SPItem *path = static_cast<SPItem *>(_pm._path);
m.setup(_desktop, true, path); // We will not try to snap to "path" itself
Inkscape::SnapCandidatePoint scp(new_pos, Inkscape::SNAPSOURCE_OTHER_HANDLE);
Inkscape::SnappedPoint sp = m.freeSnap(scp, Geom::OptRect(), false);
new_pos = sp.getPoint();
m.unSetup();
}
// Magic Bezier Drag Equations follow!
// "weight" describes how the influence of the drag should be distributed
// among the handles; 0 = front handle only, 1 = back handle only.
double weight, t = _t;
if (t <= 1.0 / 6.0) weight = 0;
else if (t <= 0.5) weight = (pow((6 * t - 1) / 2.0, 3)) / 2;
else if (t <= 5.0 / 6.0) weight = (1 - pow((6 * (1-t) - 1) / 2.0, 3)) / 2 + 0.5;
else weight = 1;
Geom::Point delta = new_pos - position();
Geom::Point offset0 = ((1-weight)/(3*t*(1-t)*(1-t))) * delta;
Geom::Point offset1 = (weight/(3*t*t*(1-t))) * delta;
//modified so that, if the trace is bspline, it only acts if the SHIFT key is pressed
if(!_pm._isBSpline()){
first->front()->move(first->front()->position() + offset0);
second->back()->move(second->back()->position() + offset1);
}else if(weight>=0.8){
if(held_shift(*event)){
second->back()->move(new_pos);
} else {
second->move(second->position() + delta);
}
}else if(weight<=0.2){
if(held_shift(*event)){
first->back()->move(new_pos);
} else {
first->move(first->position() + delta);
}
}else{
first->move(first->position() + delta);
second->move(second->position() + delta);
}
_pm.update();
}
bool CurveDragPoint::grabbed(GdkEventMotion */*event*/)
{
_pm._selection.hideTransformHandles();
NodeList::iterator second = first.next();
// move the handles to 1/3 the length of the segment for line segments
if (first->front()->isDegenerate() && second->back()->isDegenerate()) {
_segment_was_degenerate = true;
// delta is a vector equal 1/3 of distance from first to second
Geom::Point delta = (second->position() - first->position()) / 3.0;
// only update the nodes if the mode is bspline
if(!_pm._isBSpline()){
first->front()->move(first->front()->position() + delta);
second->back()->move(second->back()->position() - delta);
}
_pm.update();
} else {
_segment_was_degenerate = false;
}
return false;
}
