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"
30 /**
31 * Construct a SnapManager for a SPNamedView.
32 *
33 * \param v `Owning' SPNamedView.
34 */
36 SnapManager::SnapManager(SPNamedView const *v) :
37 guide(v, 0),
38 object(v, 0),
39 _named_view(v),
40 _include_item_center(false)
41 {
43 }
46 /**
47 * \return List of snappers that we use.
48 */
49 SnapManager::SnapperList
50 SnapManager::getSnappers() const
51 {
52 SnapManager::SnapperList s;
53 s.push_back(&guide);
54 s.push_back(&object);
56 SnapManager::SnapperList gs = getGridSnappers();
57 s.splice(s.begin(), gs);
59 return s;
60 }
62 /**
63 * \return List of gridsnappers that we use.
64 */
65 SnapManager::SnapperList
66 SnapManager::getGridSnappers() const
67 {
68 SnapperList s;
70 //FIXME: this code should actually do this: add new grid snappers that are active for this desktop. now it just adds all gridsnappers
71 SPDesktop* desktop = SP_ACTIVE_DESKTOP;
72 if (desktop && desktop->gridsEnabled()) {
73 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
74 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
75 s.push_back(grid->snapper);
76 }
77 }
79 return s;
80 }
82 /**
83 * \return true if one of the snappers will try to snap something.
84 */
86 bool SnapManager::SomeSnapperMightSnap() const
87 {
88 SnapperList const s = getSnappers();
89 SnapperList::const_iterator i = s.begin();
90 while (i != s.end() && (*i)->ThisSnapperMightSnap() == false) {
91 i++;
92 }
94 return (i != s.end());
95 }
97 /*
98 * The snappers have too many parameters to adjust individually. Therefore only
99 * two snapping modes are presented to the user: snapping bounding box corners (to
100 * other bounding boxes, grids or guides), and/or snapping nodes (to other nodes,
101 * paths, grids or guides). To select either of these modes (or both), use the
102 * methods defined below: setSnapModeBBox() and setSnapModeNode().
103 *
104 * */
107 void SnapManager::setSnapModeBBox(bool enabled)
108 {
109 //The default values are being set in sp_namedview_set() (in sp-namedview.cpp)
110 guide.setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
112 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
113 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
114 grid->snapper->setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
115 }
117 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX, enabled);
118 object.setSnapToBBoxNode(enabled);
119 object.setSnapToBBoxPath(enabled);
120 object.setStrictSnapping(true); //don't snap bboxes to nodes/paths and vice versa
121 }
123 bool SnapManager::getSnapModeBBox() const
124 {
125 return guide.getSnapFrom(Inkscape::Snapper::SNAPPOINT_BBOX);
126 }
128 void SnapManager::setSnapModeNode(bool enabled)
129 {
130 guide.setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
132 for ( GSList const *l = _named_view->grids; l != NULL; l = l->next) {
133 Inkscape::CanvasGrid *grid = (Inkscape::CanvasGrid*) l->data;
134 grid->snapper->setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
135 }
137 object.setSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE, enabled);
138 //object.setSnapToItemNode(enabled); // On second thought, these should be controlled
139 //object.setSnapToItemPath(enabled); // separately by the snapping prefs dialog
140 object.setStrictSnapping(true);
141 }
143 bool SnapManager::getSnapModeNode() const
144 {
145 return guide.getSnapFrom(Inkscape::Snapper::SNAPPOINT_NODE);
146 }
148 /**
149 * Try to snap a point to any interested snappers.
150 *
151 * \param t Type of point.
152 * \param p Point.
153 * \param it Item to ignore when snapping.
154 * \return Snapped point.
155 */
157 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
158 NR::Point const &p,
159 SPItem const *it) const
161 {
162 std::list<SPItem const *> lit;
163 lit.push_back(it);
164 return freeSnap(t, p, lit);
165 }
168 /**
169 * Try to snap a point to any interested snappers.
170 *
171 * \param t Type of point.
172 * \param p Point.
173 * \param it List of items to ignore when snapping.
174 * \return Snapped point.
175 */
177 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
178 NR::Point const &p,
179 std::list<SPItem const *> const &it) const
180 {
181 SnapperList const snappers = getSnappers();
183 return freeSnap(t, p, it, snappers);
184 }
186 /**
187 * Try to snap a point to any of the specified snappers.
188 *
189 * \param t Type of point.
190 * \param p Point.
191 * \param it List of items to ignore when snapping.
192 * \param snappers List of snappers to try to snap to
193 * \return Snapped point.
194 */
196 Inkscape::SnappedPoint SnapManager::freeSnap(Inkscape::Snapper::PointType t,
197 NR::Point const &p,
198 std::list<SPItem const *> const &it,
199 SnapperList const &snappers) const
200 {
201 Inkscape::SnappedPoint r(p, NR_HUGE);
203 for (SnapperList::const_iterator i = snappers.begin(); i != snappers.end(); i++) {
204 Inkscape::SnappedPoint const s = (*i)->freeSnap(t, p, it);
205 if (s.getDistance() < r.getDistance()) {
206 r = s;
207 }
208 }
210 return r;
211 }
213 /**
214 * Try to snap a point to any of the specified snappers. Snap always, ignoring the snap-distance
215 *
216 * \param t Type of point.
217 * \param p Point.
218 * \param it Item to ignore when snapping.
219 * \param snappers List of snappers to try to snap to
220 * \return Snapped point.
221 */
223 Inkscape::SnappedPoint
224 SnapManager::freeSnapAlways( Inkscape::Snapper::PointType t,
225 NR::Point const &p,
226 SPItem const *it,
227 SnapperList &snappers )
228 {
229 std::list<SPItem const *> lit;
230 lit.push_back(it);
231 return freeSnapAlways(t, p, lit, snappers);
232 }
234 /**
235 * Try to snap a point to any of the specified snappers. Snap always, ignoring the snap-distance
236 *
237 * \param t Type of point.
238 * \param p Point.
239 * \param it List of items to ignore when snapping.
240 * \param snappers List of snappers to try to snap to
241 * \return Snapped point.
242 */
244 Inkscape::SnappedPoint
245 SnapManager::freeSnapAlways( Inkscape::Snapper::PointType t,
246 NR::Point const &p,
247 std::list<SPItem const *> const &it,
248 SnapperList &snappers )
249 {
250 Inkscape::SnappedPoint r(p, NR_HUGE);
252 for (SnapperList::iterator i = snappers.begin(); i != snappers.end(); i++) {
253 gdouble const curr_gridsnap = (*i)->getDistance();
254 const_cast<Inkscape::Snapper*> (*i)->setDistance(NR_HUGE);
255 Inkscape::SnappedPoint const s = (*i)->freeSnap(t, p, it);
256 const_cast<Inkscape::Snapper*> (*i)->setDistance(curr_gridsnap);
258 if (s.getDistance() < r.getDistance()) {
259 r = s;
260 }
261 }
263 return r;
264 }
268 /**
269 * Try to snap a point to any interested snappers. A snap will only occur along
270 * a line described by a Inkscape::Snapper::ConstraintLine.
271 *
272 * \param t Type of point.
273 * \param p Point.
274 * \param c Constraint line.
275 * \param it Item to ignore when snapping.
276 * \return Snapped point.
277 */
279 Inkscape::SnappedPoint SnapManager::constrainedSnap(Inkscape::Snapper::PointType t,
280 NR::Point const &p,
281 Inkscape::Snapper::ConstraintLine const &c,
282 SPItem const *it) const
283 {
284 std::list<SPItem const *> lit;
285 lit.push_back(it);
286 return constrainedSnap(t, p, c, lit);
287 }
291 /**
292 * Try to snap a point to any interested snappers. A snap will only occur along
293 * a line described by a Inkscape::Snapper::ConstraintLine.
294 *
295 * \param t Type of point.
296 * \param p Point.
297 * \param c Constraint line.
298 * \param it List of items to ignore when snapping.
299 * \return Snapped point.
300 */
302 Inkscape::SnappedPoint SnapManager::constrainedSnap(Inkscape::Snapper::PointType t,
303 NR::Point const &p,
304 Inkscape::Snapper::ConstraintLine const &c,
305 std::list<SPItem const *> const &it) const
306 {
307 Inkscape::SnappedPoint r(p, NR_HUGE);
309 SnapperList const snappers = getSnappers();
310 for (SnapperList::const_iterator i = snappers.begin(); i != snappers.end(); i++) {
311 Inkscape::SnappedPoint const s = (*i)->constrainedSnap(t, p, c, it);
312 if (s.getDistance() < r.getDistance()) {
313 r = s;
314 }
315 }
317 return r;
318 }
322 /**
323 * Main internal snapping method, which is called by the other, friendlier, public
324 * methods. It's a bit hairy as it has lots of parameters, but it saves on a lot
325 * of duplicated code.
326 *
327 * \param type Type of points being snapped.
328 * \param points List of points to snap.
329 * \param ignore List of items to ignore while snapping.
330 * \param constrained true if the snap is constrained.
331 * \param constraint Constraint line to use, if `constrained' is true, otherwise undefined.
332 * \param transformation_type Type of transformation to apply to points before trying to snap them.
333 * \param transformation Description of the transformation; details depend on the type.
334 * \param origin Origin of the transformation, if applicable.
335 * \param dim Dimension of the transformation, if applicable.
336 * \param uniform true if the transformation should be uniform, if applicable.
337 */
339 std::pair<NR::Point, bool> SnapManager::_snapTransformed(
340 Inkscape::Snapper::PointType type,
341 std::vector<NR::Point> const &points,
342 std::list<SPItem const *> const &ignore,
343 bool constrained,
344 Inkscape::Snapper::ConstraintLine const &constraint,
345 Transformation transformation_type,
346 NR::Point const &transformation,
347 NR::Point const &origin,
348 NR::Dim2 dim,
349 bool uniform) const
350 {
351 /* We have a list of points, which we are proposing to transform in some way. We need to see
352 ** if any of these points, when transformed, snap to anything. If they do, we return the
353 ** appropriate transformation with `true'; otherwise we return the original scale with `false'.
354 */
356 /* Quick check to see if we have any snappers that are enabled */
357 if (SomeSnapperMightSnap() == false) {
358 return std::make_pair(transformation, false);
359 }
361 /* The current best transformation */
362 NR::Point best_transformation = transformation;
364 /* The current best metric for the best transformation; lower is better, NR_HUGE
365 ** means that we haven't snapped anything.
366 */
367 double best_metric = NR_HUGE;
369 for (std::vector<NR::Point>::const_iterator i = points.begin(); i != points.end(); i++) {
371 /* Work out the transformed version of this point */
372 NR::Point transformed;
373 switch (transformation_type) {
374 case TRANSLATION:
375 transformed = *i + transformation;
376 break;
377 case SCALE:
378 transformed = ((*i - origin) * NR::scale(transformation[NR::X], transformation[NR::Y])) + origin;
379 break;
380 case STRETCH:
381 {
382 NR::scale s(1, 1);
383 if (uniform)
384 s[NR::X] = s[NR::Y] = transformation[dim];
385 else {
386 s[dim] = transformation[dim];
387 s[1 - dim] = 1;
388 }
389 transformed = ((*i - origin) * s) + origin;
390 break;
391 }
392 case SKEW:
393 transformed = *i;
394 transformed[dim] += transformation[dim] * ((*i)[1 - dim] - origin[1 - dim]);
395 break;
396 default:
397 g_assert_not_reached();
398 }
400 /* Snap it */
401 Inkscape::SnappedPoint const snapped = constrained ?
402 constrainedSnap(type, transformed, constraint, ignore) : freeSnap(type, transformed, ignore);
404 if (snapped.getDistance() < NR_HUGE) {
405 /* We snapped. Find the transformation that describes where the snapped point has
406 ** ended up, and also the metric for this transformation.
407 */
408 NR::Point result;
409 NR::Coord metric;
410 switch (transformation_type) {
411 case TRANSLATION:
412 result = snapped.getPoint() - *i;
413 metric = NR::L2(result);
414 break;
415 case SCALE:
416 {
417 NR::Point const a = (snapped.getPoint() - origin);
418 NR::Point const b = (*i - origin);
419 result = NR::Point(a[NR::X] / b[NR::X], a[NR::Y] / b[NR::Y]);
420 metric = std::abs(NR::L2(result) - NR::L2(transformation));
421 break;
422 }
423 case STRETCH:
424 {
425 for (int j = 0; j < 2; j++) {
426 if (uniform || j == dim) {
427 result[j] = (snapped.getPoint()[dim] - origin[dim]) / ((*i)[dim] - origin[dim]);
428 } else {
429 result[j] = 1;
430 }
431 }
432 metric = std::abs(result[dim] - transformation[dim]);
433 break;
434 }
435 case SKEW:
436 result[dim] = (snapped.getPoint()[dim] - (*i)[dim]) / ((*i)[1 - dim] - origin[1 - dim]);
437 metric = std::abs(result[dim] - transformation[dim]);
438 break;
439 default:
440 g_assert_not_reached();
441 }
443 /* Note it if it's the best so far */
444 if (metric < best_metric) {
445 best_transformation = result;
446 best_metric = metric;
447 }
448 }
449 }
451 // Using " < 1e6" instead of " < NR::HUGE" for catching some rounding errors
452 // These rounding errors might be caused by NRRects, see bug #1584301
453 return std::make_pair(best_transformation, best_metric < 1e6);
454 }
457 /**
458 * Try to snap a list of points to any interested snappers after they have undergone
459 * a translation.
460 *
461 * \param t Type of points.
462 * \param p Points.
463 * \param it List of items to ignore when snapping.
464 * \param tr Proposed translation.
465 * \return Snapped translation, if a snap occurred, and a flag indicating whether a snap occurred.
466 */
468 std::pair<NR::Point, bool> SnapManager::freeSnapTranslation(Inkscape::Snapper::PointType t,
469 std::vector<NR::Point> const &p,
470 std::list<SPItem const *> const &it,
471 NR::Point const &tr) const
472 {
473 return _snapTransformed(
474 t, p, it, false, NR::Point(), TRANSLATION, tr, NR::Point(), NR::X, false
475 );
476 }
479 /**
480 * Try to snap a list of points to any interested snappers after they have undergone a
481 * translation. A snap will only occur along a line described by a
482 * Inkscape::Snapper::ConstraintLine.
483 *
484 * \param t Type of points.
485 * \param p Points.
486 * \param it List of items to ignore when snapping.
487 * \param c Constraint line.
488 * \param tr Proposed translation.
489 * \return Snapped translation, if a snap occurred, and a flag indicating whether a snap occurred.
490 */
492 std::pair<NR::Point, bool> SnapManager::constrainedSnapTranslation(Inkscape::Snapper::PointType t,
493 std::vector<NR::Point> const &p,
494 std::list<SPItem const *> const &it,
495 Inkscape::Snapper::ConstraintLine const &c,
496 NR::Point const &tr) const
497 {
498 return _snapTransformed(
499 t, p, it, true, c, TRANSLATION, tr, NR::Point(), NR::X, false
500 );
501 }
504 /**
505 * Try to snap a list of points to any interested snappers after they have undergone
506 * a scale.
507 *
508 * \param t Type of points.
509 * \param p Points.
510 * \param it List of items to ignore when snapping.
511 * \param s Proposed scale.
512 * \param o Origin of proposed scale.
513 * \return Snapped scale, if a snap occurred, and a flag indicating whether a snap occurred.
514 */
516 std::pair<NR::scale, bool> SnapManager::freeSnapScale(Inkscape::Snapper::PointType t,
517 std::vector<NR::Point> const &p,
518 std::list<SPItem const *> const &it,
519 NR::scale const &s,
520 NR::Point const &o) const
521 {
522 return _snapTransformed(
523 t, p, it, false, NR::Point(), SCALE, NR::Point(s[NR::X], s[NR::Y]), o, NR::X, false
524 );
525 }
528 /**
529 * Try to snap a list of points to any interested snappers after they have undergone
530 * a scale. A snap will only occur along a line described by a
531 * Inkscape::Snapper::ConstraintLine.
532 *
533 * \param t Type of points.
534 * \param p Points.
535 * \param it List of items to ignore when snapping.
536 * \param s Proposed scale.
537 * \param o Origin of proposed scale.
538 * \return Snapped scale, if a snap occurred, and a flag indicating whether a snap occurred.
539 */
541 std::pair<NR::scale, bool> SnapManager::constrainedSnapScale(Inkscape::Snapper::PointType t,
542 std::vector<NR::Point> const &p,
543 std::list<SPItem const *> const &it,
544 Inkscape::Snapper::ConstraintLine const &c,
545 NR::scale const &s,
546 NR::Point const &o) const
547 {
548 return _snapTransformed(
549 t, p, it, true, c, SCALE, NR::Point(s[NR::X], s[NR::Y]), o, NR::X, false
550 );
551 }
554 /**
555 * Try to snap a list of points to any interested snappers after they have undergone
556 * a stretch.
557 *
558 * \param t Type of points.
559 * \param p Points.
560 * \param it List of items to ignore when snapping.
561 * \param s Proposed stretch.
562 * \param o Origin of proposed stretch.
563 * \param d Dimension in which to apply proposed stretch.
564 * \param u true if the stretch should be uniform (ie to be applied equally in both dimensions)
565 * \return Snapped stretch, if a snap occurred, and a flag indicating whether a snap occurred.
566 */
568 std::pair<NR::Coord, bool> SnapManager::freeSnapStretch(Inkscape::Snapper::PointType t,
569 std::vector<NR::Point> const &p,
570 std::list<SPItem const *> const &it,
571 NR::Coord const &s,
572 NR::Point const &o,
573 NR::Dim2 d,
574 bool u) const
575 {
576 std::pair<NR::Point, bool> const r = _snapTransformed(
577 t, p, it, false, NR::Point(), STRETCH, NR::Point(s, s), o, d, u
578 );
580 return std::make_pair(r.first[d], r.second);
581 }
584 /**
585 * Try to snap a list of points to any interested snappers after they have undergone
586 * a skew.
587 *
588 * \param t Type of points.
589 * \param p Points.
590 * \param it List of items to ignore when snapping.
591 * \param s Proposed skew.
592 * \param o Origin of proposed skew.
593 * \param d Dimension in which to apply proposed skew.
594 * \return Snapped skew, if a snap occurred, and a flag indicating whether a snap occurred.
595 */
597 std::pair<NR::Coord, bool> SnapManager::freeSnapSkew(Inkscape::Snapper::PointType t,
598 std::vector<NR::Point> const &p,
599 std::list<SPItem const *> const &it,
600 NR::Coord const &s,
601 NR::Point const &o,
602 NR::Dim2 d) const
603 {
604 std::pair<NR::Point, bool> const r = _snapTransformed(
605 t, p, it, false, NR::Point(), SKEW, NR::Point(s, s), o, d, false
606 );
608 return std::make_pair(r.first[d], r.second);
609 }
611 /*
612 Local Variables:
613 mode:c++
614 c-file-style:"stroustrup"
615 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
616 indent-tabs-mode:nil
617 fill-column:99
618 End:
619 */
620 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :