9faa4fae6f22fcd4b7ba67fe89cad42444b1f8f5
1 #define __SP_DESKTOP_SNAP_C__
3 /**
4 * \file snap.cpp
5 * \brief SnapManager class.
6 *
7 * Authors:
8 * Lauris Kaplinski <lauris@kaplinski.com>
9 * Frank Felfe <innerspace@iname.com>
10 * Nathan Hurst <njh@njhurst.com>
11 * Carl Hetherington <inkscape@carlh.net>
12 *
13 * Copyright (C) 2006-2007 Johan Engelen <johan@shouraizou.nl>
14 * Copyrigth (C) 2004 Nathan Hurst
15 * Copyright (C) 1999-2002 Authors
16 *
17 * Released under GNU GPL, read the file 'COPYING' for more information
18 */
20 #include <utility>
22 #include "sp-namedview.h"
23 #include "snap.h"
24 #include "snapped-line.h"
26 #include <libnr/nr-point-fns.h>
27 #include <libnr/nr-scale-ops.h>
28 #include <libnr/nr-values.h>
30 #include "display/canvas-grid.h"
32 #include "inkscape.h"
33 #include "desktop.h"
34 #include "sp-guide.h"
35 using std::vector;
37 /**
38 * Construct a SnapManager for a SPNamedView.
39 *
40 * \param v `Owning' SPNamedView.
41 */
43 SnapManager::SnapManager(SPNamedView const *v) :
44 guide(v, 0),
45 object(v, 0),
46 _named_view(v),
47 _include_item_center(false),
48 _snap_enabled_globally(true)
49 {
50 }
53 /**
54 * \return List of snappers that we use.
55 */
56 SnapManager::SnapperList
57 SnapManager::getSnappers() const
58 {
59 SnapManager::SnapperList s;
60 s.push_back(&guide);
61 s.push_back(&object);
63 SnapManager::SnapperList gs = getGridSnappers();
64 s.splice(s.begin(), gs);
66 return s;
67 }
69 /**
70 * \return List of gridsnappers that we use.
71 */
72 SnapManager::SnapperList
73 SnapManager::getGridSnappers() const
74 {
75 SnapperList s;
77 //FIXME: this code should actually do this: add new grid snappers that are active for this desktop. now it just adds all gridsnappers
78 SPDesktop* desktop = SP_ACTIVE_DESKTOP;
79 if (desktop && desktop->gridsEnabled()) {
80 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
81 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
82 s.push_back(grid->snapper);
83 }
84 }
86 return s;
87 }
89 /**
90 * \return true if one of the snappers will try to snap something.
91 */
93 bool SnapManager::SomeSnapperMightSnap() const
94 {
95 if (!_snap_enabled_globally) {
96 return false;
97 }
99 SnapperList const s = getSnappers();
100 SnapperList::const_iterator i = s.begin();
101 while (i != s.end() && (*i)->ThisSnapperMightSnap() == false) {
102 i++;
103 }
105 return (i != s.end());
106 }
108 /*
109 * The snappers have too many parameters to adjust individually. Therefore only
110 * two snapping modes are presented to the user: snapping bounding box corners (to
111 * other bounding boxes, grids or guides), and/or snapping nodes (to other nodes,
112 * paths, grids or guides). To select either of these modes (or both), use the
113 * methods defined below: setSnapModeBBox() and setSnapModeNode().
114 *
115 * */
118 void SnapManager::setSnapModeBBox(bool enabled)
119 {
120 //The default values are being set in sp_namedview_set() (in sp-namedview.cpp)
121 guide.setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
123 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
124 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
125 grid->snapper->setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
126 }
128 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
129 //object.setSnapToBBoxNode(enabled); // On second thought, these should be controlled
130 //object.setSnapToBBoxPath(enabled); // separately by the snapping prefs dialog
131 object.setStrictSnapping(true); //don't snap bboxes to nodes/paths and vice versa
132 }
134 bool SnapManager::getSnapModeBBox() const
135 {
136 return guide.getSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX);
137 }
139 void SnapManager::setSnapModeNode(bool enabled)
140 {
141 guide.setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
143 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
144 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
145 grid->snapper->setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
146 }
148 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
149 //object.setSnapToItemNode(enabled); // On second thought, these should be controlled
150 //object.setSnapToItemPath(enabled); // separately by the snapping prefs dialog
151 object.setStrictSnapping(true);
152 }
154 bool SnapManager::getSnapModeNode() const
155 {
156 return guide.getSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE);
157 }
159 void SnapManager::setSnapModeGuide(bool enabled)
160 {
161 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_GUIDE, enabled);
162 }
164 bool SnapManager::getSnapModeGuide() const
165 {
166 return object.getSnapFrom(Inkscape::Snapper::SNAPPOINT_GUIDE);
167 }
169 /**
170 * Try to snap a point to any interested snappers.
171 *
172 * \param t Type of point.
173 * \param p Point.
174 * \param it Item to ignore when snapping.
175 * \return Snapped point.
176 */
178 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
179 NR::Point const &p,
180 SPItem const *it) const
182 {
183 std::list<SPItem const *> lit;
184 lit.push_back(it);
186 std::vector<NR::Point> points_to_snap;
187 points_to_snap.push_back(p);
189 return freeSnap(t, p, true, points_to_snap, lit);
190 }
192 /**
193 * Try to snap a point to any of the specified snappers.
194 *
195 * \param t Type of point.
196 * \param p Point.
197 * \param first_point If true then this point is the first one from a whole bunch of points
198 * \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
199 * \param it List of items to ignore when snapping.
200 * \param snappers List of snappers to try to snap to
201 * \return Snapped point.
202 */
204 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
205 NR::Point const &p,
206 bool const &first_point,
207 std::vector<NR::Point> &points_to_snap,
208 std::list<SPItem const *> const &it) const
209 {
211 SnappedConstraints sc;
213 SnapperList const snappers = getSnappers();
215 for (SnapperList::const_iterator i = snappers.begin(); i != snappers.end(); i++) {
216 (*i)->freeSnap(sc, t, p, first_point, points_to_snap, it);
217 }
219 return findBestSnap(p, sc);
220 }
222 /**
223 * Try to snap a point to any interested snappers. A snap will only occur along
224 * a line described by a Inkscape::Snapper::ConstraintLine.
225 *
226 * \param t Type of point.
227 * \param p Point.
228 * \param c Constraint line.
229 * \param it Item to ignore when snapping.
230 * \return Snapped point.
231 */
233 Inkscape::SnappedPoint SnapManager::constrainedSnap(Inkscape::Snapper::PointType t,
234 NR::Point const &p,
235 Inkscape::Snapper::ConstraintLine const &c,
236 SPItem const *it) const
237 {
238 std::list<SPItem const *> lit;
239 lit.push_back(it);
241 std::vector<NR::Point> points_to_snap;
242 points_to_snap.push_back(p);
244 return constrainedSnap(t, p, true, points_to_snap, c, lit);
245 }
249 /**
250 * Try to snap a point to any interested snappers. A snap will only occur along
251 * a line described by a Inkscape::Snapper::ConstraintLine.
252 *
253 * \param t Type of point.
254 * \param p Point.
255 * \param first_point If true then this point is the first one from a whole bunch of points
256 * \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
257 * \param c Constraint line.
258 * \param it List of items to ignore when snapping.
259 * \return Snapped point.
260 */
262 Inkscape::SnappedPoint SnapManager::constrainedSnap(Inkscape::Snapper::PointType t,
263 NR::Point const &p,
264 bool const &first_point,
265 std::vector<NR::Point> &points_to_snap,
266 Inkscape::Snapper::ConstraintLine const &c,
267 std::list<SPItem const *> const &it) const
268 {
270 SnappedConstraints sc;
272 SnapperList const snappers = getSnappers();
273 for (SnapperList::const_iterator i = snappers.begin(); i != snappers.end(); i++) {
274 (*i)->constrainedSnap(sc, t, p, first_point, points_to_snap, c, it);
275 }
277 return findBestSnap(p, sc);
278 }
280 Inkscape::SnappedPoint SnapManager::guideSnap(NR::Point const &p,
281 NR::Point const &guide_normal) const
282 {
283 Inkscape::ObjectSnapper::DimensionToSnap snap_dim;
284 if (guide_normal == component_vectors[NR::Y]) {
285 snap_dim = Inkscape::ObjectSnapper::SNAP_Y;
286 } else if (guide_normal == component_vectors[NR::X]) {
287 snap_dim = Inkscape::ObjectSnapper::SNAP_X;
288 } else {
289 g_warning("WARNING: snapping of angled guides is not supported yet!");
290 snap_dim = Inkscape::ObjectSnapper::SNAP_XY;
291 }
293 SnappedConstraints sc;
294 object.guideSnap(sc, p, snap_dim);
296 return findBestSnap(p, sc);
297 }
300 /**
301 * Main internal snapping method, which is called by the other, friendlier, public
302 * methods. It's a bit hairy as it has lots of parameters, but it saves on a lot
303 * of duplicated code.
304 *
305 * \param type Type of points being snapped.
306 * \param points List of points to snap.
307 * \param ignore List of items to ignore while snapping.
308 * \param constrained true if the snap is constrained.
309 * \param constraint Constraint line to use, if `constrained' is true, otherwise undefined.
310 * \param transformation_type Type of transformation to apply to points before trying to snap them.
311 * \param transformation Description of the transformation; details depend on the type.
312 * \param origin Origin of the transformation, if applicable.
313 * \param dim Dimension of the transformation, if applicable.
314 * \param uniform true if the transformation should be uniform, if applicable.
315 */
317 std::pair<NR::Point, bool> SnapManager::_snapTransformed(
318 Inkscape::Snapper::PointType type,
319 std::vector<NR::Point> const &points,
320 std::list<SPItem const *> const &ignore,
321 bool constrained,
322 Inkscape::Snapper::ConstraintLine const &constraint,
323 Transformation transformation_type,
324 NR::Point const &transformation,
325 NR::Point const &origin,
326 NR::Dim2 dim,
327 bool uniform) const
328 {
329 /* We have a list of points, which we are proposing to transform in some way. We need to see
330 ** if any of these points, when transformed, snap to anything. If they do, we return the
331 ** appropriate transformation with `true'; otherwise we return the original scale with `false'.
332 */
334 /* Quick check to see if we have any snappers that are enabled
335 ** Also used to globally disable all snapping
336 */
337 if (SomeSnapperMightSnap() == false) {
338 return std::make_pair(transformation, false);
339 }
341 std::vector<NR::Point> transformed_points;
343 for (std::vector<NR::Point>::const_iterator i = points.begin(); i != points.end(); i++) {
345 /* Work out the transformed version of this point */
346 NR::Point transformed;
347 switch (transformation_type) {
348 case TRANSLATION:
349 transformed = *i + transformation;
350 break;
351 case SCALE:
352 transformed = ((*i - origin) * NR::scale(transformation[NR::X], transformation[NR::Y])) + origin;
353 break;
354 case STRETCH:
355 {
356 NR::scale s(1, 1);
357 if (uniform)
358 s[NR::X] = s[NR::Y] = transformation[dim];
359 else {
360 s[dim] = transformation[dim];
361 s[1 - dim] = 1;
362 }
363 transformed = ((*i - origin) * s) + origin;
364 break;
365 }
366 case SKEW:
367 transformed = *i;
368 transformed[dim] += transformation[dim] * ((*i)[1 - dim] - origin[1 - dim]);
369 break;
370 default:
371 g_assert_not_reached();
372 }
374 // add the current transformed point to the box hulling all transformed points
375 transformed_points.push_back(transformed);
376 }
378 /* The current best transformation */
379 NR::Point best_transformation = transformation;
381 /* The current best metric for the best transformation; lower is better, NR_HUGE
382 ** means that we haven't snapped anything.
383 */
384 NR::Coord best_metric = NR_HUGE;
385 NR::Coord best_second_metric = NR_HUGE;
386 bool best_at_intersection = false;
388 std::vector<NR::Point>::const_iterator j = transformed_points.begin();
390 //std::cout << std::endl;
392 for (std::vector<NR::Point>::const_iterator i = points.begin(); i != points.end(); i++) {
394 /* Snap it */
395 Inkscape::SnappedPoint const snapped = constrained ?
396 constrainedSnap(type, *j, i == points.begin(), transformed_points, constraint, ignore) : freeSnap(type, *j, i == points.begin(), transformed_points, ignore);
398 NR::Point result;
399 NR::Coord metric = NR_HUGE;
400 NR::Coord second_metric = NR_HUGE;
402 if (snapped.getDistance() < NR_HUGE) {
403 /* We snapped. Find the transformation that describes where the snapped point has
404 ** ended up, and also the metric for this transformation.
405 */
406 switch (transformation_type) {
407 case TRANSLATION:
408 result = snapped.getPoint() - *i;
409 /* Consider the case in which a box is almost aligned with a grid in both
410 * horizontal and vertical directions. The distance to the intersection of
411 * the grid lines will always be larger then the distance to a single grid
412 * line. If we prefer snapping to an intersection instead of to a single
413 * grid line, then we cannot use "metric = NR::L2(result)". Therefore the
414 * snapped distance will be used as a metric. Please note that the snapped
415 * distance is defined as the distance to the nearest line of the intersection,
416 * and not to the intersection itself!
417 */
418 metric = snapped.getDistance(); //used to be: metric = NR::L2(result);
419 second_metric = snapped.getSecondDistance();
420 break;
421 case SCALE:
422 {
423 NR::Point const a = (snapped.getPoint() - origin);
424 NR::Point const b = (*i - origin);
425 result = NR::Point(a[NR::X] / b[NR::X], a[NR::Y] / b[NR::Y]);
426 metric = std::abs(NR::L2(result) - NR::L2(transformation));
427 break;
428 }
429 case STRETCH:
430 {
431 for (int a = 0; a < 2; a++) {
432 if (uniform || a == dim) {
433 result[a] = (snapped.getPoint()[dim] - origin[dim]) / ((*i)[dim] - origin[dim]);
434 } else {
435 result[a] = 1;
436 }
437 }
438 metric = std::abs(result[dim] - transformation[dim]);
439 break;
440 }
441 case SKEW:
442 result[dim] = (snapped.getPoint()[dim] - (*i)[dim]) / ((*i)[1 - dim] - origin[1 - dim]);
443 metric = std::abs(result[dim] - transformation[dim]);
444 break;
445 default:
446 g_assert_not_reached();
447 }
449 /* Note it if it's the best so far */
450 bool const c1 = metric < best_metric;
451 bool const c2 = metric == best_metric && snapped.getAtIntersection() == true && best_at_intersection == false;
452 bool const c3a = metric == best_metric && snapped.getAtIntersection() == true && best_at_intersection == true;
453 bool const c3b = second_metric < best_second_metric;
455 if (c1 || c2 || c3a && c3b) {
456 best_transformation = result;
457 best_metric = metric;
458 best_second_metric = second_metric;
459 best_at_intersection = snapped.getAtIntersection();
460 //std::cout << "SEL ";
461 } //else { std::cout << " ";}
462 }
464 //std::cout << "P_orig = " << (*i) << " | metric = " << metric << " | distance = " << snapped.getDistance() << " | second metric = " << second_metric << " | P_snap = " << snapped.getPoint() << std::endl;
465 j++;
466 }
468 // Using " < 1e6" instead of " < NR_HUGE" for catching some rounding errors
469 // These rounding errors might be caused by NRRects, see bug #1584301
470 return std::make_pair(best_transformation, best_metric < 1e6);
471 }
474 /**
475 * Try to snap a list of points to any interested snappers after they have undergone
476 * a translation.
477 *
478 * \param t Type of points.
479 * \param p Points.
480 * \param it List of items to ignore when snapping.
481 * \param tr Proposed translation.
482 * \return Snapped translation, if a snap occurred, and a flag indicating whether a snap occurred.
483 */
485 std::pair<NR::Point, bool> SnapManager::freeSnapTranslation(Inkscape::Snapper::PointType t,
486 std::vector<NR::Point> const &p,
487 std::list<SPItem const *> const &it,
488 NR::Point const &tr) const
489 {
490 return _snapTransformed(
491 t, p, it, false, NR::Point(), TRANSLATION, tr, NR::Point(), NR::X, false
492 );
493 }
496 /**
497 * Try to snap a list of points to any interested snappers after they have undergone a
498 * translation. A snap will only occur along a line described by a
499 * Inkscape::Snapper::ConstraintLine.
500 *
501 * \param t Type of points.
502 * \param p Points.
503 * \param it List of items to ignore when snapping.
504 * \param c Constraint line.
505 * \param tr Proposed translation.
506 * \return Snapped translation, if a snap occurred, and a flag indicating whether a snap occurred.
507 */
509 std::pair<NR::Point, bool> SnapManager::constrainedSnapTranslation(Inkscape::Snapper::PointType t,
510 std::vector<NR::Point> const &p,
511 std::list<SPItem const *> const &it,
512 Inkscape::Snapper::ConstraintLine const &c,
513 NR::Point const &tr) const
514 {
515 return _snapTransformed(
516 t, p, it, true, c, TRANSLATION, tr, NR::Point(), NR::X, false
517 );
518 }
521 /**
522 * Try to snap a list of points to any interested snappers after they have undergone
523 * a scale.
524 *
525 * \param t Type of points.
526 * \param p Points.
527 * \param it List of items to ignore when snapping.
528 * \param s Proposed scale.
529 * \param o Origin of proposed scale.
530 * \return Snapped scale, if a snap occurred, and a flag indicating whether a snap occurred.
531 */
533 std::pair<NR::scale, bool> SnapManager::freeSnapScale(Inkscape::Snapper::PointType t,
534 std::vector<NR::Point> const &p,
535 std::list<SPItem const *> const &it,
536 NR::scale const &s,
537 NR::Point const &o) const
538 {
539 return _snapTransformed(
540 t, p, it, false, NR::Point(), SCALE, NR::Point(s[NR::X], s[NR::Y]), o, NR::X, false
541 );
542 }
545 /**
546 * Try to snap a list of points to any interested snappers after they have undergone
547 * a scale. A snap will only occur along a line described by a
548 * Inkscape::Snapper::ConstraintLine.
549 *
550 * \param t Type of points.
551 * \param p Points.
552 * \param it List of items to ignore when snapping.
553 * \param s Proposed scale.
554 * \param o Origin of proposed scale.
555 * \return Snapped scale, if a snap occurred, and a flag indicating whether a snap occurred.
556 */
558 std::pair<NR::scale, bool> SnapManager::constrainedSnapScale(Inkscape::Snapper::PointType t,
559 std::vector<NR::Point> const &p,
560 std::list<SPItem const *> const &it,
561 Inkscape::Snapper::ConstraintLine const &c,
562 NR::scale const &s,
563 NR::Point const &o) const
564 {
565 return _snapTransformed(
566 t, p, it, true, c, SCALE, NR::Point(s[NR::X], s[NR::Y]), o, NR::X, false
567 );
568 }
571 /**
572 * Try to snap a list of points to any interested snappers after they have undergone
573 * a stretch.
574 *
575 * \param t Type of points.
576 * \param p Points.
577 * \param it List of items to ignore when snapping.
578 * \param s Proposed stretch.
579 * \param o Origin of proposed stretch.
580 * \param d Dimension in which to apply proposed stretch.
581 * \param u true if the stretch should be uniform (ie to be applied equally in both dimensions)
582 * \return Snapped stretch, if a snap occurred, and a flag indicating whether a snap occurred.
583 */
585 std::pair<NR::Coord, bool> SnapManager::freeSnapStretch(Inkscape::Snapper::PointType t,
586 std::vector<NR::Point> const &p,
587 std::list<SPItem const *> const &it,
588 NR::Coord const &s,
589 NR::Point const &o,
590 NR::Dim2 d,
591 bool u) const
592 {
593 std::pair<NR::Point, bool> const r = _snapTransformed(
594 t, p, it, false, NR::Point(), STRETCH, NR::Point(s, s), o, d, u
595 );
597 return std::make_pair(r.first[d], r.second);
598 }
601 /**
602 * Try to snap a list of points to any interested snappers after they have undergone
603 * a skew.
604 *
605 * \param t Type of points.
606 * \param p Points.
607 * \param it List of items to ignore when snapping.
608 * \param s Proposed skew.
609 * \param o Origin of proposed skew.
610 * \param d Dimension in which to apply proposed skew.
611 * \return Snapped skew, if a snap occurred, and a flag indicating whether a snap occurred.
612 */
614 std::pair<NR::Coord, bool> SnapManager::freeSnapSkew(Inkscape::Snapper::PointType t,
615 std::vector<NR::Point> const &p,
616 std::list<SPItem const *> const &it,
617 NR::Coord const &s,
618 NR::Point const &o,
619 NR::Dim2 d) const
620 {
621 std::pair<NR::Point, bool> const r = _snapTransformed(
622 t, p, it, false, NR::Point(), SKEW, NR::Point(s, s), o, d, false
623 );
625 return std::make_pair(r.first[d], r.second);
626 }
628 Inkscape::SnappedPoint SnapManager::findBestSnap(NR::Point const &p, SnappedConstraints &sc) const
629 {
630 NR::Coord const guide_sens = guide.getDistance();
631 NR::Coord grid_sens = 0;
633 SnapManager::SnapperList const gs = getGridSnappers();
634 SnapperList::const_iterator i = gs.begin();
635 if (i != gs.end()) {
636 grid_sens = (*i)->getDistance();
637 }
639 // Store all snappoints, optionally together with their specific snapping range
640 std::list<std::pair<Inkscape::SnappedPoint, NR::Coord> > sp_list;
641 // Most of these snapped points are already within the snapping range, because
642 // they have already been filtered by their respective snappers. In that case
643 // we can set the snapping range to NR_HUGE here. If however we're looking at
644 // intersections of e.g. a grid and guide line, then we'll have to determine
645 // once again whether we're within snapping range. In this case we will set
646 // the snapping range to e.g. min(guide_sens, grid_sens)
648 // search for the closest snapped point
649 Inkscape::SnappedPoint closestPoint;
650 if (getClosestSP(sc.points, closestPoint)) {
651 sp_list.push_back(std::make_pair(closestPoint, NR_HUGE));
652 }
654 // search for the closest snapped line segment
655 Inkscape::SnappedLineSegment closestLineSegment;
656 if (getClosestSLS(sc.lines, closestLineSegment)) {
657 sp_list.push_back(std::make_pair(Inkscape::SnappedPoint(closestLineSegment), NR_HUGE));
658 }
660 if (_intersectionLS) {
661 // search for the closest snapped intersection of line segments
662 Inkscape::SnappedPoint closestLineSegmentIntersection;
663 if (getClosestIntersectionSLS(sc.lines, closestLineSegmentIntersection)) {
664 sp_list.push_back(std::make_pair(closestLineSegmentIntersection, NR_HUGE));
665 }
666 }
668 // search for the closest snapped grid line
669 Inkscape::SnappedLine closestGridLine;
670 if (getClosestSL(sc.grid_lines, closestGridLine)) {
671 sp_list.push_back(std::make_pair(Inkscape::SnappedPoint(closestGridLine), NR_HUGE));
672 }
674 // search for the closest snapped guide line
675 Inkscape::SnappedLine closestGuideLine;
676 if (getClosestSL(sc.guide_lines, closestGuideLine)) {
677 sp_list.push_back(std::make_pair(Inkscape::SnappedPoint(closestGuideLine), NR_HUGE));
678 }
680 // search for the closest snapped intersection of grid lines
681 Inkscape::SnappedPoint closestGridPoint;
682 if (getClosestIntersectionSL(sc.grid_lines, closestGridPoint)) {
683 sp_list.push_back(std::make_pair(closestGridPoint, NR_HUGE));
684 }
686 // search for the closest snapped intersection of guide lines
687 Inkscape::SnappedPoint closestGuidePoint;
688 if (getClosestIntersectionSL(sc.guide_lines, closestGuidePoint)) {
689 sp_list.push_back(std::make_pair(closestGuidePoint, NR_HUGE));
690 }
692 // search for the closest snapped intersection of grid with guide lines
693 if (_intersectionGG) {
694 Inkscape::SnappedPoint closestGridGuidePoint;
695 if (getClosestIntersectionSL(sc.grid_lines, sc.guide_lines, closestGridGuidePoint)) {
696 sp_list.push_back(std::make_pair(closestGridGuidePoint, std::min(guide_sens, grid_sens)));
697 }
698 }
700 // now let's see which snapped point gets a thumbs up
701 Inkscape::SnappedPoint bestPoint(p, NR_HUGE);
702 for (std::list<std::pair<Inkscape::SnappedPoint, NR::Coord> >::const_iterator i = sp_list.begin(); i != sp_list.end(); i++) {
703 // first find out if this snapped point is within snapping range
704 if ((*i).first.getDistance() <= (*i).second) {
705 // if it's the first point
706 bool c1 = (i == sp_list.begin());
707 // or, if it's closer
708 bool c2 = (*i).first.getDistance() < bestPoint.getDistance();
709 // or, if it's just as close then consider the second distance
710 // (which is only relevant for points at an intersection)
711 bool c3a = ((*i).first.getDistance() == bestPoint.getDistance());
712 bool c3b = (*i).first.getSecondDistance() < bestPoint.getSecondDistance();
713 // then prefer this point over the previous one
714 if (c1 || c2 || c3a && c3b) {
715 bestPoint = (*i).first;
716 }
717 }
718 }
719 return bestPoint;
720 }
722 /*
723 Local Variables:
724 mode:c++
725 c-file-style:"stroustrup"
726 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
727 indent-tabs-mode:nil
728 fill-column:99
729 End:
730 */
731 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :