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 * Carl Hetherington <inkscape@carlh.net>
11 *
12 * Copyright (C) 2006-2007 Johan Engelen <johan@shouraizou.nl>
13 * Copyright (C) 1999-2002 Authors
14 *
15 * Released under GNU GPL, read the file 'COPYING' for more information
16 */
18 #include "sp-namedview.h"
19 #include "snap.h"
21 #include <libnr/nr-point-fns.h>
22 #include <libnr/nr-scale-ops.h>
23 #include <libnr/nr-values.h>
25 #include "display/canvas-grid.h"
27 #include "inkscape.h"
28 #include "desktop.h"
29 #include "sp-guide.h"
30 using std::vector;
32 /**
33 * Construct a SnapManager for a SPNamedView.
34 *
35 * \param v `Owning' SPNamedView.
36 */
38 SnapManager::SnapManager(SPNamedView const *v) :
39 guide(v, 0),
40 object(v, 0),
41 _named_view(v),
42 _include_item_center(false)
43 {
45 }
48 /**
49 * \return List of snappers that we use.
50 */
51 SnapManager::SnapperList
52 SnapManager::getSnappers() const
53 {
54 SnapManager::SnapperList s;
55 s.push_back(&guide);
56 s.push_back(&object);
58 SnapManager::SnapperList gs = getGridSnappers();
59 s.splice(s.begin(), gs);
61 return s;
62 }
64 /**
65 * \return List of gridsnappers that we use.
66 */
67 SnapManager::SnapperList
68 SnapManager::getGridSnappers() const
69 {
70 SnapperList s;
72 //FIXME: this code should actually do this: add new grid snappers that are active for this desktop. now it just adds all gridsnappers
73 SPDesktop* desktop = SP_ACTIVE_DESKTOP;
74 if (desktop && desktop->gridsEnabled()) {
75 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
76 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
77 s.push_back(grid->snapper);
78 }
79 }
81 return s;
82 }
84 /**
85 * \return true if one of the snappers will try to snap something.
86 */
88 bool SnapManager::SomeSnapperMightSnap() const
89 {
90 SnapperList const s = getSnappers();
91 SnapperList::const_iterator i = s.begin();
92 while (i != s.end() && (*i)->ThisSnapperMightSnap() == false) {
93 i++;
94 }
96 return (i != s.end());
97 }
99 /*
100 * The snappers have too many parameters to adjust individually. Therefore only
101 * two snapping modes are presented to the user: snapping bounding box corners (to
102 * other bounding boxes, grids or guides), and/or snapping nodes (to other nodes,
103 * paths, grids or guides). To select either of these modes (or both), use the
104 * methods defined below: setSnapModeBBox() and setSnapModeNode().
105 *
106 * */
109 void SnapManager::setSnapModeBBox(bool enabled)
110 {
111 //The default values are being set in sp_namedview_set() (in sp-namedview.cpp)
112 guide.setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
114 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
115 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
116 grid->snapper->setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
117 }
119 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
120 object.setSnapToBBoxNode(enabled);
121 object.setSnapToBBoxPath(enabled);
122 object.setStrictSnapping(true); //don't snap bboxes to nodes/paths and vice versa
123 }
125 bool SnapManager::getSnapModeBBox() const
126 {
127 return guide.getSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX);
128 }
130 void SnapManager::setSnapModeNode(bool enabled)
131 {
132 guide.setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
134 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
135 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
136 grid->snapper->setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
137 }
139 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
140 //object.setSnapToItemNode(enabled); // On second thought, these should be controlled
141 //object.setSnapToItemPath(enabled); // separately by the snapping prefs dialog
142 object.setStrictSnapping(true);
143 }
145 bool SnapManager::getSnapModeNode() const
146 {
147 return guide.getSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE);
148 }
150 void SnapManager::setSnapModeGuide(bool enabled)
151 {
152 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_GUIDE, enabled);
153 }
155 bool SnapManager::getSnapModeGuide() const
156 {
157 return object.getSnapFrom(Inkscape::Snapper::SNAPPOINT_GUIDE);
158 }
160 /**
161 * Try to snap a point to any interested snappers.
162 *
163 * \param t Type of point.
164 * \param p Point.
165 * \param it Item to ignore when snapping.
166 * \return Snapped point.
167 */
169 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
170 NR::Point const &p,
171 SPItem const *it) const
173 {
174 std::list<SPItem const *> lit;
175 lit.push_back(it);
177 std::vector<NR::Point> points_to_snap;
178 points_to_snap.push_back(p);
180 return freeSnap(t, p, true, points_to_snap, lit);
181 }
184 /**
185 * Try to snap a point to any interested snappers.
186 *
187 * \param t Type of point.
188 * \param p Point.
189 * \param first_point If true then this point is the first one from a whole bunch of points
190 * \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
191 * \param it List of items to ignore when snapping.
192 * \return Snapped point.
193 */
195 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
196 NR::Point const &p,
197 bool const &first_point,
198 std::vector<NR::Point> &points_to_snap,
199 std::list<SPItem const *> const &it) const
200 {
201 SnapperList const snappers = getSnappers();
203 return freeSnap(t, p, first_point, points_to_snap, it, snappers);
204 }
206 /**
207 * Try to snap a point to any of the specified snappers.
208 *
209 * \param t Type of point.
210 * \param p Point.
211 * \param first_point If true then this point is the first one from a whole bunch of points
212 * \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
213 * \param it List of items to ignore when snapping.
214 * \param snappers List of snappers to try to snap to
215 * \return Snapped point.
216 */
218 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
219 NR::Point const &p,
220 bool const &first_point,
221 std::vector<NR::Point> &points_to_snap,
222 std::list<SPItem const *> const &it,
223 SnapperList const &snappers) const
224 {
225 Inkscape::SnappedPoint r(p, NR_HUGE);
227 for (SnapperList::const_iterator i = snappers.begin(); i != snappers.end(); i++) {
228 Inkscape::SnappedPoint const s = (*i)->freeSnap(t, p, first_point, points_to_snap, it);
229 if (s.getDistance() < r.getDistance()) {
230 r = s;
231 }
232 }
234 return r;
235 }
237 /**
238 * Try to snap a point to any of the specified snappers. Snap always, ignoring the snap-distance
239 *
240 * \param t Type of point.
241 * \param p Point.
242 * \param it Item to ignore when snapping.
243 * \param snappers List of snappers to try to snap to
244 * \return Snapped point.
245 */
247 Inkscape::SnappedPoint
248 SnapManager::freeSnapAlways( Inkscape::Snapper::PointType t,
249 NR::Point const &p,
250 SPItem const *it,
251 SnapperList &snappers )
252 {
253 std::list<SPItem const *> lit;
254 lit.push_back(it);
255 return freeSnapAlways(t, p, lit, snappers);
256 }
258 /**
259 * Try to snap a point to any of the specified snappers. Snap always, ignoring the snap-distance
260 *
261 * \param t Type of point.
262 * \param p Point.
263 * \param it List of items to ignore when snapping.
264 * \param snappers List of snappers to try to snap to
265 * \return Snapped point.
266 */
268 Inkscape::SnappedPoint
269 SnapManager::freeSnapAlways( Inkscape::Snapper::PointType t,
270 NR::Point const &p,
271 std::list<SPItem const *> const &it,
272 SnapperList &snappers )
273 {
274 Inkscape::SnappedPoint r(p, NR_HUGE);
276 for (SnapperList::iterator i = snappers.begin(); i != snappers.end(); i++) {
277 gdouble const curr_gridsnap = (*i)->getDistance();
278 const_cast<Inkscape::Snapper*> (*i)->setDistance(NR_HUGE);
279 std::vector<NR::Point> points_to_snap;
280 points_to_snap.push_back(p);
281 Inkscape::SnappedPoint const s = (*i)->freeSnap(t, p, true, points_to_snap, it);
282 const_cast<Inkscape::Snapper*> (*i)->setDistance(curr_gridsnap);
284 if (s.getDistance() < r.getDistance()) {
285 r = s;
286 }
287 }
289 return r;
290 }
294 /**
295 * Try to snap a point to any interested snappers. A snap will only occur along
296 * a line described by a Inkscape::Snapper::ConstraintLine.
297 *
298 * \param t Type of point.
299 * \param p Point.
300 * \param c Constraint line.
301 * \param it Item to ignore when snapping.
302 * \return Snapped point.
303 */
305 Inkscape::SnappedPoint SnapManager::constrainedSnap(Inkscape::Snapper::PointType t,
306 NR::Point const &p,
307 Inkscape::Snapper::ConstraintLine const &c,
308 SPItem const *it) const
309 {
310 std::list<SPItem const *> lit;
311 lit.push_back(it);
313 std::vector<NR::Point> points_to_snap;
314 points_to_snap.push_back(p);
316 return constrainedSnap(t, p, true, points_to_snap, c, lit);
317 }
321 /**
322 * Try to snap a point to any interested snappers. A snap will only occur along
323 * a line described by a Inkscape::Snapper::ConstraintLine.
324 *
325 * \param t Type of point.
326 * \param p Point.
327 * \param first_point If true then this point is the first one from a whole bunch of points
328 * \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
329 * \param c Constraint line.
330 * \param it List of items to ignore when snapping.
331 * \return Snapped point.
332 */
334 Inkscape::SnappedPoint SnapManager::constrainedSnap(Inkscape::Snapper::PointType t,
335 NR::Point const &p,
336 bool const &first_point,
337 std::vector<NR::Point> &points_to_snap,
338 Inkscape::Snapper::ConstraintLine const &c,
339 std::list<SPItem const *> const &it) const
340 {
341 Inkscape::SnappedPoint r(p, NR_HUGE);
343 SnapperList const snappers = getSnappers();
344 for (SnapperList::const_iterator i = snappers.begin(); i != snappers.end(); i++) {
345 Inkscape::SnappedPoint const s = (*i)->constrainedSnap(t, p, first_point, points_to_snap, c, it);
346 if (s.getDistance() < r.getDistance()) {
347 r = s;
348 }
349 }
351 return r;
352 }
354 Inkscape::SnappedPoint SnapManager::guideSnap(NR::Point const &p,
355 NR::Point const &guide_normal) const
356 {
357 Inkscape::ObjectSnapper::DimensionToSnap snap_dim;
358 if (guide_normal == component_vectors[NR::Y]) {
359 snap_dim = Inkscape::ObjectSnapper::SNAP_Y;
360 } else if (guide_normal == component_vectors[NR::X]) {
361 snap_dim = Inkscape::ObjectSnapper::SNAP_X;
362 } else {
363 g_warning("WARNING: snapping of angled guides is not supported yet!");
364 snap_dim = Inkscape::ObjectSnapper::SNAP_XY;
365 }
367 return object.guideSnap(p, snap_dim);
368 }
371 /**
372 * Main internal snapping method, which is called by the other, friendlier, public
373 * methods. It's a bit hairy as it has lots of parameters, but it saves on a lot
374 * of duplicated code.
375 *
376 * \param type Type of points being snapped.
377 * \param points List of points to snap.
378 * \param ignore List of items to ignore while snapping.
379 * \param constrained true if the snap is constrained.
380 * \param constraint Constraint line to use, if `constrained' is true, otherwise undefined.
381 * \param transformation_type Type of transformation to apply to points before trying to snap them.
382 * \param transformation Description of the transformation; details depend on the type.
383 * \param origin Origin of the transformation, if applicable.
384 * \param dim Dimension of the transformation, if applicable.
385 * \param uniform true if the transformation should be uniform, if applicable.
386 */
388 std::pair<NR::Point, bool> SnapManager::_snapTransformed(
389 Inkscape::Snapper::PointType type,
390 std::vector<NR::Point> const &points,
391 std::list<SPItem const *> const &ignore,
392 bool constrained,
393 Inkscape::Snapper::ConstraintLine const &constraint,
394 Transformation transformation_type,
395 NR::Point const &transformation,
396 NR::Point const &origin,
397 NR::Dim2 dim,
398 bool uniform) const
399 {
400 /* We have a list of points, which we are proposing to transform in some way. We need to see
401 ** if any of these points, when transformed, snap to anything. If they do, we return the
402 ** appropriate transformation with `true'; otherwise we return the original scale with `false'.
403 */
405 /* Quick check to see if we have any snappers that are enabled */
406 if (SomeSnapperMightSnap() == false) {
407 return std::make_pair(transformation, false);
408 }
410 std::vector<NR::Point> transformed_points;
412 for (std::vector<NR::Point>::const_iterator i = points.begin(); i != points.end(); i++) {
414 /* Work out the transformed version of this point */
415 NR::Point transformed;
416 switch (transformation_type) {
417 case TRANSLATION:
418 transformed = *i + transformation;
419 break;
420 case SCALE:
421 transformed = ((*i - origin) * NR::scale(transformation[NR::X], transformation[NR::Y])) + origin;
422 break;
423 case STRETCH:
424 {
425 NR::scale s(1, 1);
426 if (uniform)
427 s[NR::X] = s[NR::Y] = transformation[dim];
428 else {
429 s[dim] = transformation[dim];
430 s[1 - dim] = 1;
431 }
432 transformed = ((*i - origin) * s) + origin;
433 break;
434 }
435 case SKEW:
436 transformed = *i;
437 transformed[dim] += transformation[dim] * ((*i)[1 - dim] - origin[1 - dim]);
438 break;
439 default:
440 g_assert_not_reached();
441 }
443 // add the current transformed point to the box hulling all transformed points
444 transformed_points.push_back(transformed);
445 }
447 /* The current best transformation */
448 NR::Point best_transformation = transformation;
450 /* The current best metric for the best transformation; lower is better, NR_HUGE
451 ** means that we haven't snapped anything.
452 */
453 double best_metric = NR_HUGE;
455 std::vector<NR::Point>::const_iterator j = transformed_points.begin();
457 for (std::vector<NR::Point>::const_iterator i = points.begin(); i != points.end(); i++) {
459 /* Snap it */
460 Inkscape::SnappedPoint const snapped = constrained ?
461 constrainedSnap(type, *j, i == points.begin(), transformed_points, constraint, ignore) : freeSnap(type, *j, i == points.begin(), transformed_points, ignore);
463 if (snapped.getDistance() < NR_HUGE) {
464 /* We snapped. Find the transformation that describes where the snapped point has
465 ** ended up, and also the metric for this transformation.
466 */
467 NR::Point result;
468 NR::Coord metric;
469 switch (transformation_type) {
470 case TRANSLATION:
471 result = snapped.getPoint() - *i;
472 metric = NR::L2(result);
473 break;
474 case SCALE:
475 {
476 NR::Point const a = (snapped.getPoint() - origin);
477 NR::Point const b = (*i - origin);
478 result = NR::Point(a[NR::X] / b[NR::X], a[NR::Y] / b[NR::Y]);
479 metric = std::abs(NR::L2(result) - NR::L2(transformation));
480 break;
481 }
482 case STRETCH:
483 {
484 for (int j = 0; j < 2; j++) {
485 if (uniform || j == dim) {
486 result[j] = (snapped.getPoint()[dim] - origin[dim]) / ((*i)[dim] - origin[dim]);
487 } else {
488 result[j] = 1;
489 }
490 }
491 metric = std::abs(result[dim] - transformation[dim]);
492 break;
493 }
494 case SKEW:
495 result[dim] = (snapped.getPoint()[dim] - (*i)[dim]) / ((*i)[1 - dim] - origin[1 - dim]);
496 metric = std::abs(result[dim] - transformation[dim]);
497 break;
498 default:
499 g_assert_not_reached();
500 }
502 /* Note it if it's the best so far */
503 if (metric < best_metric) {
504 best_transformation = result;
505 best_metric = metric;
506 }
507 }
509 j++;
510 }
512 // Using " < 1e6" instead of " < NR::HUGE" for catching some rounding errors
513 // These rounding errors might be caused by NRRects, see bug #1584301
514 return std::make_pair(best_transformation, best_metric < 1e6);
515 }
518 /**
519 * Try to snap a list of points to any interested snappers after they have undergone
520 * a translation.
521 *
522 * \param t Type of points.
523 * \param p Points.
524 * \param it List of items to ignore when snapping.
525 * \param tr Proposed translation.
526 * \return Snapped translation, if a snap occurred, and a flag indicating whether a snap occurred.
527 */
529 std::pair<NR::Point, bool> SnapManager::freeSnapTranslation(Inkscape::Snapper::PointType t,
530 std::vector<NR::Point> const &p,
531 std::list<SPItem const *> const &it,
532 NR::Point const &tr) const
533 {
534 return _snapTransformed(
535 t, p, it, false, NR::Point(), TRANSLATION, tr, NR::Point(), NR::X, false
536 );
537 }
540 /**
541 * Try to snap a list of points to any interested snappers after they have undergone a
542 * translation. A snap will only occur along a line described by a
543 * Inkscape::Snapper::ConstraintLine.
544 *
545 * \param t Type of points.
546 * \param p Points.
547 * \param it List of items to ignore when snapping.
548 * \param c Constraint line.
549 * \param tr Proposed translation.
550 * \return Snapped translation, if a snap occurred, and a flag indicating whether a snap occurred.
551 */
553 std::pair<NR::Point, bool> SnapManager::constrainedSnapTranslation(Inkscape::Snapper::PointType t,
554 std::vector<NR::Point> const &p,
555 std::list<SPItem const *> const &it,
556 Inkscape::Snapper::ConstraintLine const &c,
557 NR::Point const &tr) const
558 {
559 return _snapTransformed(
560 t, p, it, true, c, TRANSLATION, tr, NR::Point(), NR::X, false
561 );
562 }
565 /**
566 * Try to snap a list of points to any interested snappers after they have undergone
567 * a scale.
568 *
569 * \param t Type of points.
570 * \param p Points.
571 * \param it List of items to ignore when snapping.
572 * \param s Proposed scale.
573 * \param o Origin of proposed scale.
574 * \return Snapped scale, if a snap occurred, and a flag indicating whether a snap occurred.
575 */
577 std::pair<NR::scale, bool> SnapManager::freeSnapScale(Inkscape::Snapper::PointType t,
578 std::vector<NR::Point> const &p,
579 std::list<SPItem const *> const &it,
580 NR::scale const &s,
581 NR::Point const &o) const
582 {
583 return _snapTransformed(
584 t, p, it, false, NR::Point(), SCALE, NR::Point(s[NR::X], s[NR::Y]), o, NR::X, false
585 );
586 }
589 /**
590 * Try to snap a list of points to any interested snappers after they have undergone
591 * a scale. A snap will only occur along a line described by a
592 * Inkscape::Snapper::ConstraintLine.
593 *
594 * \param t Type of points.
595 * \param p Points.
596 * \param it List of items to ignore when snapping.
597 * \param s Proposed scale.
598 * \param o Origin of proposed scale.
599 * \return Snapped scale, if a snap occurred, and a flag indicating whether a snap occurred.
600 */
602 std::pair<NR::scale, bool> SnapManager::constrainedSnapScale(Inkscape::Snapper::PointType t,
603 std::vector<NR::Point> const &p,
604 std::list<SPItem const *> const &it,
605 Inkscape::Snapper::ConstraintLine const &c,
606 NR::scale const &s,
607 NR::Point const &o) const
608 {
609 return _snapTransformed(
610 t, p, it, true, c, SCALE, NR::Point(s[NR::X], s[NR::Y]), o, NR::X, false
611 );
612 }
615 /**
616 * Try to snap a list of points to any interested snappers after they have undergone
617 * a stretch.
618 *
619 * \param t Type of points.
620 * \param p Points.
621 * \param it List of items to ignore when snapping.
622 * \param s Proposed stretch.
623 * \param o Origin of proposed stretch.
624 * \param d Dimension in which to apply proposed stretch.
625 * \param u true if the stretch should be uniform (ie to be applied equally in both dimensions)
626 * \return Snapped stretch, if a snap occurred, and a flag indicating whether a snap occurred.
627 */
629 std::pair<NR::Coord, bool> SnapManager::freeSnapStretch(Inkscape::Snapper::PointType t,
630 std::vector<NR::Point> const &p,
631 std::list<SPItem const *> const &it,
632 NR::Coord const &s,
633 NR::Point const &o,
634 NR::Dim2 d,
635 bool u) const
636 {
637 std::pair<NR::Point, bool> const r = _snapTransformed(
638 t, p, it, false, NR::Point(), STRETCH, NR::Point(s, s), o, d, u
639 );
641 return std::make_pair(r.first[d], r.second);
642 }
645 /**
646 * Try to snap a list of points to any interested snappers after they have undergone
647 * a skew.
648 *
649 * \param t Type of points.
650 * \param p Points.
651 * \param it List of items to ignore when snapping.
652 * \param s Proposed skew.
653 * \param o Origin of proposed skew.
654 * \param d Dimension in which to apply proposed skew.
655 * \return Snapped skew, if a snap occurred, and a flag indicating whether a snap occurred.
656 */
658 std::pair<NR::Coord, bool> SnapManager::freeSnapSkew(Inkscape::Snapper::PointType t,
659 std::vector<NR::Point> const &p,
660 std::list<SPItem const *> const &it,
661 NR::Coord const &s,
662 NR::Point const &o,
663 NR::Dim2 d) const
664 {
665 std::pair<NR::Point, bool> const r = _snapTransformed(
666 t, p, it, false, NR::Point(), SKEW, NR::Point(s, s), o, d, false
667 );
669 return std::make_pair(r.first[d], r.second);
670 }
672 /*
673 Local Variables:
674 mode:c++
675 c-file-style:"stroustrup"
676 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
677 indent-tabs-mode:nil
678 fill-column:99
679 End:
680 */
681 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :