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-rw-r--r--src/snapped-curve.cpp260
1 files changed, 260 insertions, 0 deletions
diff --git a/src/snapped-curve.cpp b/src/snapped-curve.cpp
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+++ b/src/snapped-curve.cpp
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * \file src/snapped-curve.cpp
+ * SnappedCurve class.
+ *
+ * Authors:
+ * Diederik van Lierop <mail@diedenrezi.nl>
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "snapped-curve.h"
+#include <2geom/path-intersection.h>
+
+Inkscape::SnappedCurve::SnappedCurve(Geom::Point const &snapped_point, Geom::Point const &tangent, int num_path, int num_segm, Geom::Coord const &snapped_distance, Geom::Coord const &snapped_tolerance, bool const &always_snap, bool const &fully_constrained, Geom::Curve const *curve, SnapSourceType source, long source_num, SnapTargetType target, Geom::OptRect target_bbox)
+{
+ _num_path = num_path;
+ _num_segm = num_segm;
+ _distance = snapped_distance;
+ _tolerance = std::max(snapped_tolerance, 1.0);
+ _always_snap = always_snap;
+ _curve = curve;
+ _second_distance = Geom::infinity();
+ _second_tolerance = 1;
+ _second_always_snap = false;
+ _point = snapped_point;
+ _tangent = tangent;
+ _at_intersection = false;
+ _fully_constrained = fully_constrained;
+ _source = source;
+ _source_num = source_num;
+ _target = target;
+ _target_bbox = target_bbox;
+}
+
+Inkscape::SnappedCurve::SnappedCurve()
+{
+ _num_path = 0;
+ _num_segm = 0;
+ _distance = Geom::infinity();
+ _tolerance = 1;
+ _always_snap = false;
+ _curve = nullptr;
+ _second_distance = Geom::infinity();
+ _second_tolerance = 1;
+ _second_always_snap = false;
+ _point = Geom::Point(0,0);
+ _tangent = Geom::Point(0,0);
+ _at_intersection = false;
+ _fully_constrained = false;
+ _source = SNAPSOURCE_UNDEFINED;
+ _source_num = -1;
+ _target = SNAPTARGET_UNDEFINED;
+ _target_bbox = Geom::OptRect();
+}
+
+Inkscape::SnappedCurve::~SnappedCurve()
+= default;
+
+Inkscape::SnappedPoint Inkscape::SnappedCurve::intersect(SnappedCurve const &curve, Geom::Point const &p, Geom::Affine dt2doc) const
+{
+ // Calculate the intersections of two curves, which are both within snapping range, and
+ // return only the closest intersection
+ // The point of intersection should be considered for snapping, but might be outside the snapping range
+ // PS: We need p (the location of the mouse pointer) to find out which intersection is the
+ // closest, as there might be multiple intersections of two curves
+ Geom::Crossings cs = crossings(*(this->_curve), *(curve._curve));
+
+ if (cs.size() > 0) {
+ // There might be multiple intersections: find the closest
+ Geom::Coord best_dist = Geom::infinity();
+ Geom::Point best_p = Geom::Point(Geom::infinity(), Geom::infinity());
+ for (const auto & c : cs) {
+ Geom::Point p_ix = this->_curve->pointAt(c.ta);
+ Geom::Coord dist = Geom::distance(p_ix, p);
+
+ // Test if we have two segments (curves) from the same path..
+ if (this->_num_path == curve._num_path) {
+ // Never try to intersect a segment with itself
+ if (this->_num_segm == curve._num_segm) continue;
+ // Two subsequent segments (curves) in a path will have a common node; this node is not considered to be an intersection
+ if (this->_num_segm == curve._num_segm + 1 && c.ta == 0 && c.tb == 1) continue;
+ if (this->_num_segm + 1 == curve._num_segm && c.ta == 1 && c.tb == 0) continue;
+ }
+
+ if (dist < best_dist) {
+ best_dist = dist;
+ best_p = p_ix;
+ }
+ }
+
+ // Now we've found the closest intersection, return it as a SnappedPoint
+ bool const use_this_as_primary = _distance < curve.getSnapDistance();
+ Inkscape::SnappedCurve const *primaryC = use_this_as_primary ? this : &curve;
+ Inkscape::SnappedCurve const *secondaryC = use_this_as_primary ? &curve : this;
+
+ // The intersection should in fact be returned in desktop coordinates
+ best_p = best_p * dt2doc;
+
+ Geom::Coord primaryDist = use_this_as_primary ? Geom::L2(best_p - this->getPoint()) : Geom::L2(best_p - curve.getPoint());
+ Geom::Coord secondaryDist = use_this_as_primary ? Geom::L2(best_p - curve.getPoint()) : Geom::L2(best_p - this->getPoint());
+ // TODO: Investigate whether it is possible to use document coordinates everywhere
+ // in the snapper code. Only the mouse position should be in desktop coordinates, I guess.
+ // All paths are already in document coords and we are certainly not going to change THAT.
+ return SnappedPoint(best_p, Inkscape::SNAPSOURCE_UNDEFINED, primaryC->getSourceNum(), Inkscape::SNAPTARGET_PATH_INTERSECTION, primaryDist, primaryC->getTolerance(), primaryC->getAlwaysSnap(), true, false, true,
+ secondaryDist, secondaryC->getTolerance(), secondaryC->getAlwaysSnap());
+ }
+
+ // No intersection
+ return SnappedPoint(Geom::Point(Geom::infinity(), Geom::infinity()), SNAPSOURCE_UNDEFINED, 0, SNAPTARGET_UNDEFINED, Geom::infinity(), 0, false, false, false, false, Geom::infinity(), 0, false);
+}
+
+Inkscape::SnappedPoint Inkscape::SnappedCurve::intersect(SnappedLine const &line, Geom::Point const &p, Geom::Affine dt2doc) const
+{
+ // Calculate the intersections of a curve with a line, which are both within snapping range, and
+ // return only the closest intersection
+ // The point of intersection should be considered for snapping, but might be outside the snapping range
+ // PS: We need p (the location of the mouse pointer) to find out which intersection is the
+ // closest, as there might be multiple intersections of a single curve with a line
+
+ // 1) get a Geom::Line object from the SnappedLine
+ // 2) convert to document coordinates (line and p are in desktop coordinates, but the curves are in document coordinate)
+ // 3) create a Geom::LineSegment (i.e. a curve), because we cannot use a Geom::Line for calculating intersections
+ // (for this we will create a 2e6 pixels long linesegment, with t running from -1e6 to 1e6; this should be long
+ // enough for any practical purpose)
+ Geom::LineSegment line_segm = line.getLine().transformed(dt2doc).segment(-1e6, 1e6); //
+ const Geom::Curve *line_as_curve = dynamic_cast<Geom::Curve const*>(&line_segm);
+ Geom::Crossings cs = crossings(*(this->_curve), *line_as_curve);
+
+ if (cs.size() > 0) {
+ // There might be multiple intersections: find the closest
+ Geom::Coord best_dist = Geom::infinity();
+ Geom::Point best_p = Geom::Point(Geom::infinity(), Geom::infinity());
+ for (const auto & c : cs) {
+ Geom::Point p_ix = this->_curve->pointAt(c.ta);
+ Geom::Coord dist = Geom::distance(p_ix, p);
+
+ if (dist < best_dist) {
+ best_dist = dist;
+ best_p = p_ix;
+ }
+ }
+
+ // The intersection should in fact be returned in desktop coordinates
+ best_p = best_p * dt2doc;
+
+ // Now we've found the closest intersection, return it as a SnappedPoint
+ if (_distance < line.getSnapDistance()) {
+ // curve is the closest, so this is our primary snap target
+ return SnappedPoint(best_p, Inkscape::SNAPSOURCE_UNDEFINED, this->getSourceNum(), Inkscape::SNAPTARGET_PATH_GUIDE_INTERSECTION,
+ Geom::L2(best_p - this->getPoint()), this->getTolerance(), this->getAlwaysSnap(), true, false, true,
+ Geom::L2(best_p - line.getPoint()), line.getTolerance(), line.getAlwaysSnap());
+ } else {
+ return SnappedPoint(best_p, Inkscape::SNAPSOURCE_UNDEFINED, line.getSourceNum(), Inkscape::SNAPTARGET_PATH_GUIDE_INTERSECTION,
+ Geom::L2(best_p - line.getPoint()), line.getTolerance(), line.getAlwaysSnap(), true, false, true,
+ Geom::L2(best_p - this->getPoint()), this->getTolerance(), this->getAlwaysSnap());
+ }
+ }
+
+ // No intersection
+ return SnappedPoint(Geom::Point(Geom::infinity(), Geom::infinity()), SNAPSOURCE_UNDEFINED, 0, SNAPTARGET_UNDEFINED, Geom::infinity(), 0, false, false, false, false, Geom::infinity(), 0, false);
+}
+
+
+// search for the closest snapped line
+bool getClosestCurve(std::list<Inkscape::SnappedCurve> const &list, Inkscape::SnappedCurve &result, bool exclude_paths)
+{
+ bool success = false;
+
+ for (std::list<Inkscape::SnappedCurve>::const_iterator i = list.begin(); i != list.end(); ++i) {
+ if (exclude_paths && ((*i).getTarget() == Inkscape::SNAPTARGET_PATH)) {
+ continue;
+ }
+ if ((i == list.begin()) || (*i).getSnapDistance() < result.getSnapDistance()) {
+ result = *i;
+ success = true;
+ }
+ }
+
+ return success;
+}
+
+// search for the closest intersection of two snapped curves, which are both member of the same collection
+bool getClosestIntersectionCS(std::list<Inkscape::SnappedCurve> const &list, Geom::Point const &p, Inkscape::SnappedPoint &result, Geom::Affine dt2doc)
+{
+ bool success = false;
+
+ for (std::list<Inkscape::SnappedCurve>::const_iterator i = list.begin(); i != list.end(); ++i) {
+ if ((*i).getTarget() != Inkscape::SNAPTARGET_BBOX_EDGE) { // We don't support snapping to intersections of bboxes,
+ // as this would require two bboxes two be flashed in the snap indicator
+ std::list<Inkscape::SnappedCurve>::const_iterator j = i;
+ ++j;
+ for (; j != list.end(); ++j) {
+ if ((*j).getTarget() != Inkscape::SNAPTARGET_BBOX_EDGE) { // We don't support snapping to intersections of bboxes
+ Inkscape::SnappedPoint sp = (*i).intersect(*j, p, dt2doc);
+ if (sp.getAtIntersection()) {
+ // if it's the first point
+ bool const c1 = !success;
+ // or, if it's closer
+ bool const c2 = sp.getSnapDistance() < result.getSnapDistance();
+ // or, if it's just as close then look at the other distance
+ // (only relevant for snapped points which are at an intersection)
+ bool const c3 = (sp.getSnapDistance() == result.getSnapDistance()) && (sp.getSecondSnapDistance() < result.getSecondSnapDistance());
+ // then prefer this point over the previous one
+ if (c1 || c2 || c3) {
+ result = sp;
+ success = true;
+ }
+ }
+ }
+ }
+ }
+ }
+
+ return success;
+}
+
+// search for the closest intersection of two snapped curves, which are member of two different collections
+bool getClosestIntersectionCL(std::list<Inkscape::SnappedCurve> const &curve_list, std::list<Inkscape::SnappedLine> const &line_list, Geom::Point const &p, Inkscape::SnappedPoint &result, Geom::Affine dt2doc)
+{
+ bool success = false;
+
+ for (const auto & i : curve_list) {
+ if (i.getTarget() != Inkscape::SNAPTARGET_BBOX_EDGE) { // We don't support snapping to intersections of bboxes,
+ // as this would require two bboxes two be flashed in the snap indicator
+ for (const auto & j : line_list) {
+ if (j.getTarget() != Inkscape::SNAPTARGET_BBOX_EDGE) { // We don't support snapping to intersections of bboxes
+ Inkscape::SnappedPoint sp = i.intersect(j, p, dt2doc);
+ if (sp.getAtIntersection()) {
+ // if it's the first point
+ bool const c1 = !success;
+ // or, if it's closer
+ bool const c2 = sp.getSnapDistance() < result.getSnapDistance();
+ // or, if it's just as close then look at the other distance
+ // (only relevant for snapped points which are at an intersection)
+ bool const c3 = (sp.getSnapDistance() == result.getSnapDistance()) && (sp.getSecondSnapDistance() < result.getSecondSnapDistance());
+ // then prefer this point over the previous one
+ if (c1 || c2 || c3) {
+ result = sp;
+ success = true;
+ }
+ }
+ }
+ }
+ }
+ }
+
+ return success;
+}
+
+/*
+ Local Variables:
+ mode:c++
+ c-file-style:"stroustrup"
+ c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+ indent-tabs-mode:nil
+ fill-column:99
+ End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :