1 /**
2 * \file object-snapper.cpp
3 * \brief Snapping things to objects.
4 *
5 * Authors:
6 * Carl Hetherington <inkscape@carlh.net>
7 * Diederik van Lierop <mail@diedenrezi.nl>
8 *
9 * Copyright (C) 2005 - 2008 Authors
10 *
11 * Released under GNU GPL, read the file 'COPYING' for more information
12 */
14 #include "libnr/n-art-bpath.h"
15 #include "libnr/nr-path.h"
16 #include "libnr/nr-rect-ops.h"
17 #include "libnr/nr-point-fns.h"
18 #include "live_effects/n-art-bpath-2geom.h"
19 #include "2geom/path-intersection.h"
20 #include "document.h"
21 #include "sp-namedview.h"
22 #include "sp-image.h"
23 #include "sp-item-group.h"
24 #include "sp-item.h"
25 #include "sp-use.h"
26 #include "display/curve.h"
27 #include "desktop.h"
28 #include "inkscape.h"
29 #include "prefs-utils.h"
30 #include "sp-text.h"
31 #include "sp-flowtext.h"
32 #include "text-editing.h"
34 Inkscape::ObjectSnapper::ObjectSnapper(SPNamedView const *nv, NR::Coord const d)
35 : Snapper(nv, d), _snap_to_itemnode(true), _snap_to_itempath(true),
36 _snap_to_bboxnode(true), _snap_to_bboxpath(true), _strict_snapping(true),
37 _include_item_center(false)
38 {
39 _candidates = new std::vector<SPItem*>;
40 _points_to_snap_to = new std::vector<NR::Point>;
41 _bpaths_to_snap_to = new std::vector<NArtBpath*>;
42 _paths_to_snap_to = new std::vector<Path*>;
43 }
45 Inkscape::ObjectSnapper::~ObjectSnapper()
46 {
47 _candidates->clear(); //Don't delete the candidates themselves, as these are not ours!
48 delete _candidates;
50 _points_to_snap_to->clear();
51 delete _points_to_snap_to;
53 _clear_paths();
54 delete _paths_to_snap_to;
55 delete _bpaths_to_snap_to;
56 }
58 /**
59 * Find all items within snapping range.
60 * \param r Pointer to the current document
61 * \param it List of items to ignore
62 * \param first_point If true then this point is the first one from a whole bunch of points
63 * \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
64 * \param DimensionToSnap Snap in X, Y, or both directions.
65 */
67 void Inkscape::ObjectSnapper::_findCandidates(SPObject* r,
68 std::list<SPItem const *> const &it,
69 bool const &first_point,
70 std::vector<NR::Point> &points_to_snap,
71 DimensionToSnap const snap_dim) const
72 {
73 bool const c1 = (snap_dim == TRANSL_SNAP_XY) && ThisSnapperMightSnap();
74 bool const c2 = (snap_dim != TRANSL_SNAP_XY) && GuidesMightSnap();
75 bool const c3 = points_to_snap.size() == 0;
77 if (!(c1 || c2) || c3) {
78 return;
79 }
81 SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
83 if (first_point) {
84 _candidates->clear();
85 }
87 NR::Maybe<NR::Rect> bbox = NR::Rect(); // a default NR::Rect is infinitely large
88 NR::Coord t = getSnapperTolerance();
90 // When dragging a guide...
91 NR::Point p_guide = points_to_snap[0];
92 if (!getSnapperAlwaysSnap()) {
93 bbox = NR::Rect(p_guide, p_guide); // bbox is now just a single point: p_guide
94 bbox->growBy(t); // bbox width and height now measure 2x snapper tolerance
95 // for angled guidelines the bbox is now larger than really needed
96 // (up to sqrt(2) for 45 deg. guidelines) but we'll leave it like that
97 } // else: use an infinitely large bbox to find candidates
99 for (SPObject* o = sp_object_first_child(r); o != NULL; o = SP_OBJECT_NEXT(o)) {
100 if (SP_IS_ITEM(o) && !SP_ITEM(o)->isLocked() && !desktop->itemIsHidden(SP_ITEM(o))) {
102 /* See if this item is on the ignore list */
103 std::list<SPItem const *>::const_iterator i = it.begin();
104 while (i != it.end() && *i != o) {
105 i++;
106 }
108 if (i == it.end()) {
109 /* See if the item is within range */
110 if (SP_IS_GROUP(o)) {
111 _findCandidates(o, it, false, points_to_snap, snap_dim);
112 } else {
113 // Now let's see if any of the snapping points is within snapping range of this object
114 if (snap_dim == TRANSL_SNAP_XY) {
115 bbox = sp_item_bbox_desktop(SP_ITEM(o));
116 } // else: we're snapping a guide to an object and we will use the bbox as defined above
118 if (bbox) {
119 for (std::vector<NR::Point>::const_iterator i = points_to_snap.begin(); i != points_to_snap.end(); i++) {
120 NR::Point b_min = bbox->min();
121 NR::Point b_max = bbox->max();
122 bool withinX = ((*i)[NR::X] >= b_min[NR::X] - t) && ((*i)[NR::X] <= b_max[NR::X] + t);
123 bool withinY = ((*i)[NR::Y] >= b_min[NR::Y] - t) && ((*i)[NR::Y] <= b_max[NR::Y] + t);
124 if (withinX && withinY) {
125 //We've found a point that is within snapping range
126 //of this object, so record it as a candidate
127 _candidates->push_back(SP_ITEM(o));
128 break;
129 }
130 }
131 }
132 }
133 }
134 }
135 }
136 }
139 void Inkscape::ObjectSnapper::_collectNodes(Inkscape::Snapper::PointType const &t,
140 bool const &first_point) const
141 {
142 // Now, let's first collect all points to snap to. If we have a whole bunch of points to snap,
143 // e.g. when translating an item using the selector tool, then we will only do this for the
144 // first point and store the collection for later use. This significantly improves the performance
145 if (first_point) {
146 _points_to_snap_to->clear();
148 // Determine the type of bounding box we should snap to
149 SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
151 bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
152 bool p_is_a_bbox = t & Inkscape::Snapper::SNAPPOINT_BBOX;
153 bool p_is_a_guide = t & Inkscape::Snapper::SNAPPOINT_GUIDE;
155 // A point considered for snapping should be either a node, a bbox corner or a guide. Pick only ONE!
156 g_assert(!(p_is_a_node && p_is_a_bbox || p_is_a_bbox && p_is_a_guide || p_is_a_node && p_is_a_guide));
158 if (_snap_to_bboxnode) {
159 gchar const *prefs_bbox = prefs_get_string_attribute("tools", "bounding_box");
160 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
161 }
163 for (std::vector<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
164 //NR::Matrix i2doc(NR::identity());
165 SPItem *root_item = *i;
166 if (SP_IS_USE(*i)) {
167 root_item = sp_use_root(SP_USE(*i));
168 }
169 g_return_if_fail(root_item);
171 //Collect all nodes so we can snap to them
172 if (_snap_to_itemnode) {
173 if (!(_strict_snapping && !p_is_a_node) || p_is_a_guide) {
174 sp_item_snappoints(root_item, _include_item_center, SnapPointsIter(*_points_to_snap_to));
175 }
176 }
178 //Collect the bounding box's corners so we can snap to them
179 if (_snap_to_bboxnode) {
180 if (!(_strict_snapping && !p_is_a_bbox) || p_is_a_guide) {
181 NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(root_item, bbox_type);
182 if (b) {
183 for ( unsigned k = 0 ; k < 4 ; k++ ) {
184 _points_to_snap_to->push_back(b->corner(k));
185 }
186 }
187 }
188 }
189 }
190 }
191 }
193 void Inkscape::ObjectSnapper::_snapNodes(SnappedConstraints &sc,
194 Inkscape::Snapper::PointType const &t,
195 NR::Point const &p,
196 bool const &first_point,
197 std::vector<NR::Point> *unselected_nodes) const
198 {
199 // Iterate through all nodes, find out which one is the closest to p, and snap to it!
201 _collectNodes(t, first_point);
203 if (unselected_nodes != NULL) {
204 _points_to_snap_to->insert(_points_to_snap_to->end(), unselected_nodes->begin(), unselected_nodes->end());
205 }
207 SnappedPoint s;
208 bool success = false;
210 for (std::vector<NR::Point>::const_iterator k = _points_to_snap_to->begin(); k != _points_to_snap_to->end(); k++) {
211 NR::Coord dist = NR::L2(*k - p);
212 if (dist < getSnapperTolerance() && dist < s.getDistance()) {
213 s = SnappedPoint(*k, dist, getSnapperTolerance(), getSnapperAlwaysSnap());
214 success = true;
215 }
216 }
218 if (success) {
219 sc.points.push_back(s);
220 }
221 }
223 void Inkscape::ObjectSnapper::_snapTranslatingGuideToNodes(SnappedConstraints &sc,
224 Inkscape::Snapper::PointType const &t,
225 NR::Point const &p,
226 NR::Point const &guide_normal) const
227 {
228 // Iterate through all nodes, find out which one is the closest to this guide, and snap to it!
229 _collectNodes(t, true);
231 SnappedPoint s;
232 bool success = false;
234 NR::Coord tol = getSnapperTolerance();
236 for (std::vector<NR::Point>::const_iterator k = _points_to_snap_to->begin(); k != _points_to_snap_to->end(); k++) {
237 // Project each node (*k) on the guide line (running through point p)
238 NR::Point p_proj = project_on_linesegment(*k, p, p + NR::rot90(guide_normal));
239 NR::Coord dist = NR::L2(*k - p_proj); // distance from node to the guide
240 NR::Coord dist2 = NR::L2(p - p_proj); // distance from projection of node on the guide, to the mouse location
241 if ((dist < tol && dist2 < tol || getSnapperAlwaysSnap()) && dist < s.getDistance()) {
242 s = SnappedPoint(*k, dist, tol, getSnapperAlwaysSnap());
243 success = true;
244 }
245 }
247 if (success) {
248 sc.points.push_back(s);
249 }
250 }
252 void Inkscape::ObjectSnapper::_collectPaths(Inkscape::Snapper::PointType const &t,
253 bool const &first_point,
254 SPPath const *selected_path) const
255 {
256 // Now, let's first collect all paths to snap to. If we have a whole bunch of points to snap,
257 // e.g. when translating an item using the selector tool, then we will only do this for the
258 // first point and store the collection for later use. This significantly improves the performance
259 if (first_point) {
260 _clear_paths();
262 // Determine the type of bounding box we should snap to
263 SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
265 bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
267 if (_snap_to_bboxpath) {
268 gchar const *prefs_bbox = prefs_get_string_attribute("tools", "bounding_box");
269 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
270 }
272 /* While editing a path in the node tool, findCandidates must ignore that path because
273 * of the node snapping requirements (i.e. only unselected nodes must be snapable).
274 * This path must not be ignored however when snapping to the paths, so we add it here
275 * manually when applicable.
276 *
277 * It must be the last one in the list, as this is assumption is being used in _snapPaths()
278 */
279 if (_snap_to_itempath && selected_path != NULL) {
280 _candidates->push_back(SP_ITEM(selected_path));
281 }
283 for (std::vector<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
285 /* Transform the requested snap point to this item's coordinates */
286 NR::Matrix i2doc(NR::identity());
287 SPItem *root_item = NULL;
288 /* We might have a clone at hand, so make sure we get the root item */
289 if (SP_IS_USE(*i)) {
290 i2doc = sp_use_get_root_transform(SP_USE(*i));
291 root_item = sp_use_root(SP_USE(*i));
292 g_return_if_fail(root_item);
293 } else {
294 i2doc = sp_item_i2doc_affine(*i);
295 root_item = *i;
296 }
298 //Build a list of all paths considered for snapping to
300 //Add the item's path to snap to
301 if (_snap_to_itempath) {
302 if (!(_strict_snapping && !p_is_a_node)) {
303 // Snapping to the path of characters is very cool, but for a large
304 // chunk of text this will take ages! So limit snapping to text paths
305 // containing max. 240 characters. Snapping the bbox will not be affected
306 bool very_lenghty_prose = false;
307 if (SP_IS_TEXT(root_item) || SP_IS_FLOWTEXT(root_item)) {
308 very_lenghty_prose = sp_text_get_length(SP_TEXT(root_item)) > 240;
309 }
310 // On my AMD 3000+, the snapping lag becomes annoying at approx. 240 chars
311 // which corresponds to a lag of 500 msec. This is for snapping a rect
312 // to a single line of text.
314 // Snapping for example to a traced bitmap is also very stressing for
315 // the CPU, so we'll only snap to paths having no more than 500 nodes
316 // This also leads to a lag of approx. 500 msec (in my lousy test set-up).
317 bool very_complex_path = false;
318 if (SP_IS_PATH(root_item)) {
319 very_complex_path = sp_nodes_in_path(SP_PATH(root_item)) > 500;
320 }
322 if (!very_lenghty_prose && !very_complex_path) {
323 SPCurve *curve = curve_for_item(root_item);
324 if (curve) {
325 NArtBpath *bpath = bpath_for_curve(root_item, curve, true, true);
326 _bpaths_to_snap_to->push_back(bpath);
327 // Because we set doTransformation to true in bpath_for_curve, we
328 // will get a dupe of the path, which must be freed at some point
329 sp_curve_unref(curve);
330 }
331 }
332 }
333 }
335 //Add the item's bounding box to snap to
336 if (_snap_to_bboxpath) {
337 if (!(_strict_snapping && p_is_a_node)) {
338 NRRect rect;
339 sp_item_invoke_bbox(root_item, &rect, i2doc, TRUE, bbox_type);
340 NArtBpath *bpath = nr_path_from_rect(rect);
341 _bpaths_to_snap_to->push_back(bpath);
342 }
343 }
344 }
345 }
346 }
348 void Inkscape::ObjectSnapper::_snapPaths(SnappedConstraints &sc,
349 Inkscape::Snapper::PointType const &t,
350 NR::Point const &p,
351 bool const &first_point,
352 std::vector<NR::Point> *unselected_nodes,
353 SPPath const *selected_path) const
354 {
355 _collectPaths(t, first_point, selected_path);
357 // Now we can finally do the real snapping, using the paths collected above
358 SnappedPoint s;
359 bool success = false;
361 /* FIXME: this seems like a hack. Perhaps Snappers should be
362 ** in SPDesktop rather than SPNamedView?
363 */
364 SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
365 NR::Point const p_doc = desktop->dt2doc(p);
367 // Convert all bpaths to Paths, because here we really must have Paths
368 // (whereas in _snapPathsConstrained we will use the original bpaths)
369 if (first_point) {
370 for (std::vector<NArtBpath*>::const_iterator k = _bpaths_to_snap_to->begin(); k != _bpaths_to_snap_to->end(); k++) {
371 Path *path = bpath_to_Path(*k);
372 if (path) {
373 path->ConvertWithBackData(0.01); //This is extremely time consuming!
374 _paths_to_snap_to->push_back(path);
375 }
376 }
377 }
379 for (std::vector<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
380 if (*k) {
381 bool being_edited = false; // True if the current path is being edited in the node tool
382 if (unselected_nodes != NULL) {
383 if (unselected_nodes->size() > 0 && selected_path != NULL) { // If the node tool is active ...
384 if (*k == _paths_to_snap_to->back()) { // and we arrived at the last path in the vector ...
385 being_edited = true; // then this path is currently being edited
386 }
387 }
388 }
390 for (unsigned i = 1 ; i < (*k)->pts.size() ; i++) {
391 NR::Point start_point;
392 NR::Point end_point;
393 NR::Maybe<Path::cut_position> o = NR::Nothing();
394 if (being_edited) {
395 /* If the path is being edited, then we will try to snap to each piece of the
396 * path individually. We should only snap though to stationary pieces of the paths
397 * and not to the pieces that are being dragged around. This way we avoid
398 * self-snapping. For this we check whether the nodes at both ends of the current
399 * piece are unselected; if they are then this piece must be stationary
400 */
401 (*k)->PointAt(i, 0, start_point);
402 (*k)->PointAt(i, 1, end_point);
403 start_point = desktop->doc2dt(start_point);
404 end_point = desktop->doc2dt(end_point);
405 g_assert(unselected_nodes != NULL);
406 bool c1 = isUnselectedNode(start_point, unselected_nodes);
407 bool c2 = isUnselectedNode(end_point, unselected_nodes);
408 if (c1 && c2) {
409 o = get_nearest_position_on_Path(*k, p_doc, i);
410 }
411 } else {
412 /* If the path is NOT being edited, then we will try to snap to the path as a
413 * whole, so we need to do this only once and we will break out at the end of
414 * this for-loop iteration */
415 /* Look for the nearest position on this SPItem to our snap point */
416 o = get_nearest_position_on_Path(*k, p_doc);
417 (*k)->PointAt(o->piece, 0, start_point);
418 (*k)->PointAt(o->piece, 1, end_point);
419 start_point = desktop->doc2dt(start_point);
420 end_point = desktop->doc2dt(end_point);
421 }
423 if (o && o->t >= 0 && o->t <= 1) {
424 /* Convert the nearest point back to desktop coordinates */
425 NR::Point const o_it = get_point_on_Path(*k, o->piece, o->t);
426 NR::Point const o_dt = desktop->doc2dt(o_it);
427 NR::Coord const dist = NR::L2(o_dt - p);
429 if (dist < getSnapperTolerance()) {
430 // if we snap to a straight line segment (within a path), then return this line segment
431 if ((*k)->IsLineSegment(o->piece)) {
432 sc.lines.push_back(Inkscape::SnappedLineSegment(o_dt, dist, getSnapperTolerance(), getSnapperAlwaysSnap(), start_point, end_point));
433 } else {
434 // for segments other than straight lines of a path, we'll return just the closest snapped point
435 if (dist < s.getDistance()) {
436 s = SnappedPoint(o_dt, dist, getSnapperTolerance(), getSnapperAlwaysSnap());
437 success = true;
438 }
439 }
440 }
441 }
443 // If the path is NOT being edited, then we will try to snap to the path as a whole
444 // so we need to do this only once
445 if (!being_edited) break;
446 }
447 }
448 }
450 if (success) {
451 sc.points.push_back(s);
452 }
453 }
455 /* Returns true if point is coincident with one of the unselected nodes */
456 bool Inkscape::ObjectSnapper::isUnselectedNode(NR::Point const &point, std::vector<NR::Point> const *unselected_nodes) const
457 {
458 if (unselected_nodes == NULL) {
459 return false;
460 }
462 if (unselected_nodes->size() == 0) {
463 return false;
464 }
466 for (std::vector<NR::Point>::const_iterator i = unselected_nodes->begin(); i != unselected_nodes->end(); i++) {
467 if (NR::L2(point - *i) < 1e-4) {
468 return true;
469 }
470 }
472 return false;
473 }
475 void Inkscape::ObjectSnapper::_snapPathsConstrained(SnappedConstraints &sc,
476 Inkscape::Snapper::PointType const &t,
477 NR::Point const &p,
478 bool const &first_point,
479 ConstraintLine const &c) const
480 {
481 _collectPaths(t, first_point);
483 // Now we can finally do the real snapping, using the paths collected above
485 /* FIXME: this seems like a hack. Perhaps Snappers should be
486 ** in SPDesktop rather than SPNamedView?
487 */
488 SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
489 NR::Point const p_doc = desktop->dt2doc(p);
491 NR::Point direction_vector = c.getDirection();
492 if (!is_zero(direction_vector)) {
493 direction_vector = NR::unit_vector(direction_vector);
494 }
496 NR::Point const p1_on_cl = c.hasPoint() ? c.getPoint() : p;
497 NR::Point const p2_on_cl = p1_on_cl + direction_vector;
499 // The intersection point of the constraint line with any path,
500 // must lie within two points on the constraintline: p_min_on_cl and p_max_on_cl
501 // The distance between those points is twice the snapping tolerance
502 NR::Point const p_proj_on_cl = project_on_linesegment(p, p1_on_cl, p2_on_cl);
503 NR::Point const p_min_on_cl = desktop->dt2doc(p_proj_on_cl - getSnapperTolerance() * direction_vector);
504 NR::Point const p_max_on_cl = desktop->dt2doc(p_proj_on_cl + getSnapperTolerance() * direction_vector);
506 Geom::Path cl;
507 cl.start(p_min_on_cl.to_2geom());
508 cl.appendNew<Geom::LineSegment>(p_max_on_cl.to_2geom());
510 for (std::vector<NArtBpath*>::const_iterator k = _bpaths_to_snap_to->begin(); k != _bpaths_to_snap_to->end(); k++) {
511 if (*k) {
512 // convert a Path object (see src/livarot/Path.h) to a 2geom's path object (see 2geom/path.h)
513 // TODO: (Diederik) Only do this once for the first point, needs some storage of pointers in a member variable
514 std::vector<Geom::Path> path_2geom = BPath_to_2GeomPath(*k);
516 for (std::vector<Geom::Path>::const_iterator l = path_2geom.begin(); l != path_2geom.end(); l++) {
517 Geom::SimpleCrosser sxr;
518 Geom::Crossings crossings = sxr.crossings(*l, cl);
519 for (std::vector<Geom::Crossing>::const_iterator m = crossings.begin(); m != crossings.end(); m++) {
520 // Reconstruct the point of intersection
521 NR::Point p_inters = p_min_on_cl + ((*m).tb) * (p_max_on_cl - p_min_on_cl);
522 // When it's within snapping range, then return it
523 // (within snapping range == between p_min_on_cl and p_max_on_cl == 0 < tb < 1)
524 if ((*m).tb >= 0 && (*m).tb <= 1 ) {
525 NR::Coord dist = NR::L2(desktop->dt2doc(p_proj_on_cl) - p_inters);
526 SnappedPoint s(desktop->doc2dt(p_inters), dist, getSnapperTolerance(), getSnapperAlwaysSnap());
527 sc.points.push_back(s);
528 }
529 }
530 }
531 }
532 }
533 }
536 void Inkscape::ObjectSnapper::_doFreeSnap(SnappedConstraints &sc,
537 Inkscape::Snapper::PointType const &t,
538 NR::Point const &p,
539 bool const &first_point,
540 std::vector<NR::Point> &points_to_snap,
541 std::list<SPItem const *> const &it,
542 std::vector<NR::Point> *unselected_nodes) const
543 {
544 if ( NULL == _named_view ) {
545 return;
546 }
548 /* Get a list of all the SPItems that we will try to snap to */
549 if (first_point) {
550 _findCandidates(sp_document_root(_named_view->document), it, first_point, points_to_snap, TRANSL_SNAP_XY);
551 }
553 if (_snap_to_itemnode || _snap_to_bboxnode) {
554 _snapNodes(sc, t, p, first_point, unselected_nodes);
555 }
557 if (_snap_to_itempath || _snap_to_bboxpath) {
558 unsigned n = (unselected_nodes == NULL) ? 0 : unselected_nodes->size();
559 if (n > 0) {
560 /* While editing a path in the node tool, findCandidates must ignore that path because
561 * of the node snapping requirements (i.e. only unselected nodes must be snapable).
562 * That path must not be ignored however when snapping to the paths, so we add it here
563 * manually when applicable
564 */
565 g_assert(it.size() == 1);
566 g_assert(SP_IS_PATH(*it.begin()));
567 _snapPaths(sc, t, p, first_point, unselected_nodes, SP_PATH(*it.begin()));
568 } else {
569 _snapPaths(sc, t, p, first_point, NULL, NULL);
570 }
571 }
572 }
576 void Inkscape::ObjectSnapper::_doConstrainedSnap( SnappedConstraints &sc,
577 Inkscape::Snapper::PointType const &t,
578 NR::Point const &p,
579 bool const &first_point,
580 std::vector<NR::Point> &points_to_snap,
581 ConstraintLine const &c,
582 std::list<SPItem const *> const &it) const
583 {
584 if ( NULL == _named_view ) {
585 return;
586 }
588 /* Get a list of all the SPItems that we will try to snap to */
589 if (first_point) {
590 _findCandidates(sp_document_root(_named_view->document), it, first_point, points_to_snap, TRANSL_SNAP_XY);
591 }
593 // A constrained snap, is a snap in only one degree of freedom (specified by the constraint line).
594 // This is usefull for example when scaling an object while maintaining a fixed aspect ratio. It's
595 // nodes are only allowed to move in one direction (i.e. in one degree of freedom).
597 // When snapping to objects, we either snap to their nodes or their paths. It is however very
598 // unlikely that any node will be exactly at the constrained line, so for a constrained snap
599 // to objects we will only consider the object's paths. Beside, the nodes will be at these paths,
600 // so we will more or less snap to them anyhow.
602 if (_snap_to_itempath || _snap_to_bboxpath) {
603 _snapPathsConstrained(sc, t, p, first_point, c);
604 }
605 }
608 // This method is used to snap a guide to nodes, while dragging the guide around
609 void Inkscape::ObjectSnapper::guideSnap(SnappedConstraints &sc,
610 NR::Point const &p,
611 NR::Point const &guide_normal) const
612 {
613 if ( NULL == _named_view ) {
614 return;
615 }
617 /* Get a list of all the SPItems that we will try to snap to */
618 std::vector<SPItem*> cand;
619 std::list<SPItem const *> const it; //just an empty list
621 std::vector<NR::Point> points_to_snap;
622 points_to_snap.push_back(p);
624 DimensionToSnap snap_dim;
625 if (guide_normal == component_vectors[NR::Y]) {
626 snap_dim = GUIDE_TRANSL_SNAP_Y;
627 } else if (guide_normal == component_vectors[NR::X]) {
628 snap_dim = GUIDE_TRANSL_SNAP_X;
629 } else {
630 snap_dim = ANGLED_GUIDE_TRANSL_SNAP;
631 }
632 // We don't support ANGLED_GUIDE_ROT_SNAP yet.
634 // It would be cool to allow the user to rotate a guide by dragging it, instead of
635 // only translating it. (For example when CTRL is pressed). We will need an UI part
636 // for that first; and some important usability choices need to be made:
637 // E.g. which point should be used for pivoting? A previously snapped point,
638 // or a transformation center (which can be moved after clicking for the
639 // second time on an object; but should this point then be constrained to the
640 // line, or can it be located anywhere?)
642 _findCandidates(sp_document_root(_named_view->document), it, true, points_to_snap, snap_dim);
643 _snapTranslatingGuideToNodes(sc, Inkscape::Snapper::SNAPPOINT_GUIDE, p, guide_normal);
645 // _snapRotatingGuideToNodes has not been implemented yet.
646 }
648 /**
649 * \return true if this Snapper will snap at least one kind of point.
650 */
651 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
652 {
653 bool snap_to_something = _snap_to_itempath || _snap_to_itemnode || _snap_to_bboxpath || _snap_to_bboxnode;
654 return (_snap_enabled && _snap_from != 0 && snap_to_something);
655 }
657 bool Inkscape::ObjectSnapper::GuidesMightSnap() const
658 {
659 bool snap_to_something = _snap_to_itemnode || _snap_to_bboxnode;
660 return (_snap_enabled && (_snap_from & SNAPPOINT_GUIDE) && snap_to_something);
661 }
663 void Inkscape::ObjectSnapper::_clear_paths() const
664 {
665 for (std::vector<NArtBpath*>::const_iterator k = _bpaths_to_snap_to->begin(); k != _bpaths_to_snap_to->end(); k++) {
666 g_free(*k);
667 }
668 _bpaths_to_snap_to->clear();
670 for (std::vector<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
671 delete *k;
672 }
673 _paths_to_snap_to->clear();
674 }
676 /*
677 Local Variables:
678 mode:c++
679 c-file-style:"stroustrup"
680 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
681 indent-tabs-mode:nil
682 fill-column:99
683 End:
684 */
685 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :