src/object-snapper.cpp

   1 /**
   2  *  \file object-snapper.cpp
   3  *  \brief Snapping things to objects.
   4  *
   5  * Authors:
   6  *   Carl Hetherington <inkscape@carlh.net>
   7  *
   8  * Copyright (C) 2005 Authors
   9  *
  10  * Released under GNU GPL, read the file 'COPYING' for more information
  11  */
  12
  13 #include "libnr/n-art-bpath.h"
  14 #include "libnr/nr-rect-ops.h"
  15 #include "document.h"
  16 #include "sp-namedview.h"
  17 #include "sp-image.h"
  18 #include "sp-item-group.h"
  19 #include "sp-item.h"
  20 #include "sp-use.h"
  21 #include "display/curve.h"
  22 #include "desktop.h"
  23 #include "inkscape.h"
  24 #include "prefs-utils.h"
  25 #include "sp-text.h"
  26 #include "sp-flowtext.h"
  27 #include "text-editing.h"
  28
  29 Inkscape::ObjectSnapper::ObjectSnapper(SPNamedView const *nv, NR::Coord const d)
  30     : Snapper(nv, d), _snap_to_itemnode(true), _snap_to_itempath(true),
  31     _snap_to_bboxnode(true), _snap_to_bboxpath(true), _strict_snapping(true),
  32     _include_item_center(false)
  33 {
  34         _candidates = new std::vector<SPItem*>;
  35         _points_to_snap_to = new std::vector<NR::Point>;
  36         _paths_to_snap_to = new std::vector<Path*>;
  37 }
  38
  39 Inkscape::ObjectSnapper::~ObjectSnapper()
  40 {
  41         _candidates->clear(); //Don't delete the candidates themselves, as these are not ours!
  42         delete _candidates;
  43
  44         _points_to_snap_to->clear();
  45         delete _points_to_snap_to;
  46
  47         for (std::vector<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
  48                 delete *k;
  49     }
  50     _paths_to_snap_to->clear();
  51         delete _paths_to_snap_to;
  52 }
  53
  54 /**
  55  *      Find all items within snapping range.
  56  *      \param r Pointer to the current document
  57  *  \param it List of items to ignore
  58  *  \param first_point If true then this point is the first one from a whole bunch of points
  59  *  \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
  60  *  \param DimensionToSnap Snap in X, Y, or both directions.
  61  */
  62
  63 void Inkscape::ObjectSnapper::_findCandidates(SPObject* r,
  64                                               std::list<SPItem const *> const &it,
  65                                               bool const &first_point,
  66                                               std::vector<NR::Point> &points_to_snap,
  67                                               DimensionToSnap const snap_dim) const
  68 {
  69     if (ThisSnapperMightSnap()) {
  70         SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  71
  72         if (first_point) {
  73                         _candidates->clear();
  74         }
  75
  76         for (SPObject* o = sp_object_first_child(r); o != NULL; o = SP_OBJECT_NEXT(o)) {
  77             if (SP_IS_ITEM(o) && !SP_ITEM(o)->isLocked() && !desktop->itemIsHidden(SP_ITEM(o))) {
  78
  79                 /* See if this item is on the ignore list */
  80                 std::list<SPItem const *>::const_iterator i = it.begin();
  81                 while (i != it.end() && *i != o) {
  82                     i++;
  83                 }
  84
  85                         if (i == it.end()) {
  86                     /* See if the item is within range */
  87                     if (SP_IS_GROUP(o)) {
  88                         _findCandidates(o, it, false, points_to_snap, snap_dim);
  89                     } else {
  90                         // Now let's see if any of the snapping points is within
  91                         // snapping range of this object
  92                         NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(SP_ITEM(o));
  93                         if (b) {
  94                                 for (std::vector<NR::Point>::const_iterator i = points_to_snap.begin(); i != points_to_snap.end(); i++) {
  95                                         NR::Point b_min = b->min();
  96                                         NR::Point b_max = b->max();
  97                                         double d = getDistance();
  98                                         bool withinX = ((*i)[NR::X] >= b_min[NR::X] - d) && ((*i)[NR::X] <= b_max[NR::X] + d);
  99                                         bool withinY = ((*i)[NR::Y] >= b_min[NR::Y] - d) && ((*i)[NR::Y] <= b_max[NR::Y] + d);
 100                                         if (snap_dim == SNAP_X && withinX || snap_dim == SNAP_Y && withinY || snap_dim == SNAP_XY && withinX && withinY) {
 101                                            //We've found a point that is within snapping range
 102                                            //of this object, so record it as a candidate
 103                                            _candidates->push_back(SP_ITEM(o));
 104                                            break;
 105                                         }
 106                                 }
 107                         }
 108                     }
 109                 }
 110             }
 111         }
 112     }
 113 }
 114
 115
 116 bool Inkscape::ObjectSnapper::_snapNodes(Inkscape::Snapper::PointType const &t,
 117                                                                                  Inkscape::SnappedPoint &s,
 118                                          NR::Point const &p,
 119                                          bool const &first_point,
 120                                          DimensionToSnap const snap_dim) const
 121 {
 122     bool success = false;
 123
 124     // Determine the type of bounding box we should snap to
 125     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 126         if (_snap_to_bboxnode) {
 127                 gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 128                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 129         }
 130
 131         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 132         bool p_is_a_bbox = t & Inkscape::Snapper::SNAPPOINT_BBOX;
 133         bool p_is_a_guide = t & Inkscape::Snapper::SNAPPOINT_GUIDE;
 134
 135         // A point considered for snapping should be either a node, a bbox corner or a guide. Pick only ONE!
 136         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));
 137
 138     // Now, let's first collect all points to snap to. If we have a whole bunch of points to snap,
 139     // e.g. when translating an item using the selector tool, then we will only do this for the
 140     // first point and store the collection for later use. This dramatically improves the performance
 141         if (first_point) {
 142                 _points_to_snap_to->clear();
 143             for (std::vector<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
 144
 145                 //NR::Matrix i2doc(NR::identity());
 146                 SPItem *root_item = *i;
 147                 if (SP_IS_USE(*i)) {
 148                     root_item = sp_use_root(SP_USE(*i));
 149                 }
 150
 151                         //Collect all nodes so we can snap to them
 152                 if (_snap_to_itemnode) {
 153                         if (!(_strict_snapping && !p_is_a_node) || p_is_a_guide) {
 154                                 sp_item_snappoints(root_item, _include_item_center, SnapPointsIter(*_points_to_snap_to));
 155                                 }
 156                 }
 157
 158                 //Collect the bounding box's corners so we can snap to them
 159                 if (_snap_to_bboxnode) {
 160                         if (!(_strict_snapping && !p_is_a_bbox) || p_is_a_guide) {
 161                                 NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(root_item, bbox_type);
 162                                 if (b) {
 163                                         for ( unsigned k = 0 ; k < 4 ; k++ ) {
 164                                             _points_to_snap_to->push_back(b->corner(k));
 165                                         }
 166                                 }
 167                         }
 168                 }
 169             }
 170         }
 171
 172     //Do the snapping, using all the nodes and corners collected above
 173     for (std::vector<NR::Point>::const_iterator k = _points_to_snap_to->begin(); k != _points_to_snap_to->end(); k++) {
 174             /* Try to snap to this node of the path */
 175         NR::Coord dist = NR_HUGE;
 176         NR::Point snapped_point;
 177         switch (snap_dim) {
 178                 case SNAP_X:
 179                         dist = fabs((*k)[NR::X] - p[NR::X]);
 180                         snapped_point = NR::Point((*k)[NR::X], p[NR::Y]);
 181                         break;
 182                 case SNAP_Y:
 183                         dist = fabs((*k)[NR::Y] - p[NR::Y]);
 184                         snapped_point = NR::Point(p[NR::X], (*k)[NR::Y]);
 185                         break;
 186                 case SNAP_XY:
 187                         dist = NR::L2(*k - p);
 188                         snapped_point = *k;
 189                         break;
 190         }
 191
 192         if (dist < getDistance() && dist < s.getDistance()) {
 193             s = SnappedPoint(snapped_point, dist);
 194             success = true;
 195         }
 196     }
 197
 198     return success;
 199 }
 200
 201
 202 bool Inkscape::ObjectSnapper::_snapPaths(Inkscape::Snapper::PointType const &t,
 203                                                                                  Inkscape::SnappedPoint &s,
 204                                          NR::Point const &p,
 205                                          bool const &first_point) const
 206 {
 207     bool success = false;
 208     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 209     ** in SPDesktop rather than SPNamedView?
 210     */
 211     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 212
 213     NR::Point const p_doc = desktop->dt2doc(p);
 214
 215     // Determine the type of bounding box we should snap to
 216     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 217         if (_snap_to_bboxpath) {
 218         gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 219                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 220         }
 221
 222         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 223
 224     // Now, let's first collect all paths to snap to. If we have a whole bunch of points to snap,
 225     // e.g. when translating an item using the selector tool, then we will only do this for the
 226     // first point and store the collection for later use. This dramatically improves the performance
 227     if (first_point) {
 228             for (std::vector<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
 229                 delete *k;
 230             }
 231             _paths_to_snap_to->clear();
 232             for (std::vector<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
 233
 234                 /* Transform the requested snap point to this item's coordinates */
 235                 NR::Matrix i2doc(NR::identity());
 236                 SPItem *root_item = NULL;
 237                 /* We might have a clone at hand, so make sure we get the root item */
 238                 if (SP_IS_USE(*i)) {
 239                     i2doc = sp_use_get_root_transform(SP_USE(*i));
 240                     root_item = sp_use_root(SP_USE(*i));
 241                 } else {
 242                     i2doc = sp_item_i2doc_affine(*i);
 243                     root_item = *i;
 244                 }
 245
 246                 //Build a list of all paths considered for snapping to
 247
 248                 //Add the item's path to snap to
 249                 if (_snap_to_itempath) {
 250                         if (!(_strict_snapping && !p_is_a_node)) {
 251                                 // Snapping to the path of characters is very cool, but for a large
 252                                         // chunk of text this will take ages! So limit snapping to text paths
 253                                         // containing max. 240 characters. Snapping the bbox will not be affected
 254                                         bool very_lenghty_prose = false;
 255                                         if (SP_IS_TEXT(root_item) || SP_IS_FLOWTEXT(root_item)) {
 256                                                 very_lenghty_prose =  sp_text_get_length(SP_TEXT(root_item)) > 240;
 257                                         }
 258                                         // On my AMD 3000+, the snapping lag becomes annoying at approx. 240 chars
 259                                         // which corresponds to a lag of 500 msec. This is for snapping a rect
 260                                         // to a single line of text.
 261
 262                                         // Snapping for example to a traced bitmap is also very stressing for
 263                                         // the CPU, so we'll only snap to paths having no more than 500 nodes
 264                                         // This also leads to a lag of approx. 500 msec (in my lousy test set-up).
 265                                         bool very_complex_path = false;
 266                                         if (SP_IS_PATH(root_item)) {
 267                                                 very_complex_path = sp_nodes_in_path(SP_PATH(root_item)) > 500;
 268                                         }
 269
 270                                         if (!very_lenghty_prose && !very_complex_path) {
 271                                         _paths_to_snap_to->push_back(Path_for_item(root_item, true, true));
 272                                         }
 273                         }
 274                 }
 275
 276                 //Add the item's bounding box to snap to
 277                 if (_snap_to_bboxpath) {
 278                         if (!(_strict_snapping && p_is_a_node)) {
 279                                 //This will get ugly... rect -> curve -> bpath
 280                                 NRRect rect;
 281                                 sp_item_invoke_bbox(root_item, &rect, i2doc, TRUE, bbox_type);
 282                                 NR::Maybe<NR::Rect> bbox = rect.upgrade();
 283                                 SPCurve *curve = sp_curve_new_from_rect(bbox);
 284                                 if (curve) {
 285                                         NArtBpath *bpath = SP_CURVE_BPATH(curve);
 286                                         if (bpath) {
 287                                                 Path *path = bpath_to_Path(bpath);
 288                                                 if (path) {
 289                                                         _paths_to_snap_to->push_back(path);
 290                                                 }
 291                                                 delete bpath;
 292                                         }
 293                                         delete curve;
 294                                 }
 295                         }
 296                 }
 297             }
 298     }
 299
 300     //Now we can finally do the real snapping, using the paths collected above
 301     for (std::vector<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
 302         if (*k) {
 303             if (first_point) {
 304                 (*k)->ConvertWithBackData(0.01); //This is extremely time consuming!
 305             }
 306
 307                 /* Look for the nearest position on this SPItem to our snap point */
 308                 NR::Maybe<Path::cut_position> const o = get_nearest_position_on_Path(*k, p_doc);
 309                 if (o && o->t >= 0 && o->t <= 1) {
 310
 311                     /* Convert the nearest point back to desktop coordinates */
 312                     NR::Point const o_it = get_point_on_Path(*k, o->piece, o->t);
 313                     NR::Point const o_dt = desktop->doc2dt(o_it);
 314
 315                     NR::Coord const dist = NR::L2(o_dt - p);
 316                     if (dist < getDistance() && dist < s.getDistance()) {
 317                         s = SnappedPoint(o_dt, dist);
 318                         success = true;
 319                     }
 320                 }
 321         }
 322     }
 323
 324     return success;
 325 }
 326
 327
 328 void Inkscape::ObjectSnapper::_doFreeSnap(SnappedConstraints &sc,
 329                                                                                         Inkscape::Snapper::PointType const &t,
 330                                                                                         NR::Point const &p,
 331                                                                                         bool const &first_point,
 332                                                                 std::vector<NR::Point> &points_to_snap,
 333                                                 std::list<SPItem const *> const &it) const
 334 {
 335     if ( NULL == _named_view ) {
 336         return;
 337     }
 338
 339     /* Get a list of all the SPItems that we will try to snap to */
 340         if (first_point) {
 341                 _findCandidates(sp_document_root(_named_view->document), it, first_point, points_to_snap, SNAP_XY);
 342         }
 343
 344         SnappedPoint s(p, NR_HUGE);
 345         bool snapped_to_node = false;
 346         bool snapped_to_path = false;
 347
 348     if (_snap_to_itemnode || _snap_to_bboxnode) {
 349         snapped_to_node = _snapNodes(t, s, p, first_point, SNAP_XY);
 350     }
 351     if (_snap_to_itempath || _snap_to_bboxpath) {
 352         snapped_to_path = _snapPaths(t, s, p, first_point);
 353     }
 354
 355     if (snapped_to_node || snapped_to_path) {
 356         sc.points.push_back(s);
 357     }
 358 }
 359
 360
 361
 362 void Inkscape::ObjectSnapper::_doConstrainedSnap(SnappedConstraints &sc,
 363                                                                                                    Inkscape::Snapper::PointType const &t,
 364                                                                                                    NR::Point const &p,
 365                                                                                                    bool const &first_point,
 366                                                                                    std::vector<NR::Point> &points_to_snap,
 367                                                                    ConstraintLine const &c,
 368                                                                    std::list<SPItem const *> const &it) const
 369 {
 370     /* FIXME: this needs implementing properly; I think we have to do the
 371     ** intersection of c with the objects.
 372     */
 373     _doFreeSnap(sc, t, p, first_point, points_to_snap, it);
 374 }
 375
 376
 377
 378 Inkscape::SnappedPoint Inkscape::ObjectSnapper::guideSnap(NR::Point const &p,
 379                                                                                                                   DimensionToSnap const snap_dim) const
 380 {
 381     if ( NULL == _named_view ) {
 382         return SnappedPoint(p, NR_HUGE);
 383     }
 384
 385     /* Get a list of all the SPItems that we will try to snap to */
 386     std::vector<SPItem*> cand;
 387     std::list<SPItem const *> const it; //just an empty list
 388
 389     std::vector<NR::Point> points_to_snap;
 390     points_to_snap.push_back(p);
 391
 392     _findCandidates(sp_document_root(_named_view->document), it, true, points_to_snap, snap_dim);
 393
 394     SnappedPoint s(p, NR_HUGE);
 395     _snapNodes(Inkscape::Snapper::SNAPPOINT_GUIDE, s, p, true, snap_dim);
 396
 397     return s;
 398 }
 399
 400 /**
 401  *  \return true if this Snapper will snap at least one kind of point.
 402  */
 403 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
 404 {
 405     bool snap_to_something = _snap_to_itempath || _snap_to_itemnode || _snap_to_bboxpath || _snap_to_bboxnode;
 406     return (_enabled && _snap_from != 0 && snap_to_something);
 407 }
 408
 409
 410 /*
 411   Local Variables:
 412   mode:c++
 413   c-file-style:"stroustrup"
 414   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 415   indent-tabs-mode:nil
 416   fill-column:99
 417   End:
 418 */
 419 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :