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
  26
  27 Inkscape::ObjectSnapper::ObjectSnapper(SPNamedView const *nv, NR::Coord const d)
  28     : Snapper(nv, d), _snap_to_itemnode(true), _snap_to_itempath(true),
  29     _snap_to_bboxnode(true), _snap_to_bboxpath(true), _strict_snapping(true),
  30     _include_item_center(false)
  31 {
  32         _candidates = new std::list<SPItem*>;
  33         _points_to_snap_to = new std::list<NR::Point>;
  34         _paths_to_snap_to = new std::list<Path*>;
  35 }
  36
  37 Inkscape::ObjectSnapper::~ObjectSnapper()
  38 {
  39         _candidates->clear(); //Don't delete the candidates themselves, as these are not ours!
  40         delete _candidates;
  41
  42         _points_to_snap_to->clear();
  43         delete _points_to_snap_to;
  44
  45         for (std::list<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
  46                 delete *k;
  47     }
  48     _paths_to_snap_to->clear();
  49         delete _paths_to_snap_to;
  50 }
  51
  52 /**
  53  *      Find all items within snapping range.
  54  *      \param r Pointer to the current document
  55  *  \param it List of items to ignore
  56  *  \param first_point If true then this point is the first one from a whole bunch of points
  57  *  \param points_to_snap The whole bunch of points, all from the same selection and having the same transformation
  58  *  \param DimensionToSnap Snap in X, Y, or both directions.
  59  */
  60
  61 void Inkscape::ObjectSnapper::_findCandidates(SPObject* r,
  62                                               std::list<SPItem const *> const &it,
  63                                               bool const &first_point,
  64                                               std::vector<NR::Point> &points_to_snap,
  65                                               DimensionToSnap const snap_dim) const
  66 {
  67     if (ThisSnapperMightSnap()) {
  68         SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  69
  70         if (first_point) {
  71                 _candidates->clear();
  72
  73                 for (SPObject* o = sp_object_first_child(r); o != NULL; o = SP_OBJECT_NEXT(o)) {
  74                     if (SP_IS_ITEM(o) && !SP_ITEM(o)->isLocked() && !desktop->itemIsHidden(SP_ITEM(o))) {
  75
  76                         /* See if this item is on the ignore list */
  77                         std::list<SPItem const *>::const_iterator i = it.begin();
  78                         while (i != it.end() && *i != o) {
  79                             i++;
  80                         }
  81
  82                         if (i == it.end()) {
  83                             /* See if the item is within range */
  84                             if (SP_IS_GROUP(o)) {
  85                                 _findCandidates(o, it, false, points_to_snap, snap_dim);
  86                             } else {
  87                                 // Now let's see if any of the snapping points is within
  88                                 // snapping range of this object
  89                                 NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(SP_ITEM(o));
  90                                 if (b) {
  91                                         for (std::vector<NR::Point>::const_iterator i = points_to_snap.begin(); i != points_to_snap.end(); i++) {
  92                                                 NR::Point b_min = b->min();
  93                                                 NR::Point b_max = b->max();
  94                                                 double d = getDistance();
  95                                                 bool withinX = ((*i)[NR::X] >= b_min[NR::X] - d) && ((*i)[NR::X] <= b_max[NR::X] + d);
  96                                                 bool withinY = ((*i)[NR::Y] >= b_min[NR::Y] - d) && ((*i)[NR::Y] <= b_max[NR::Y] + d);
  97                                                 if (snap_dim == SNAP_X && withinX || snap_dim == SNAP_Y && withinY || snap_dim == SNAP_XY && withinX && withinY) {
  98                                                    //We've found a point that is within snapping range
  99                                                    //of this object, so record it as a candidate
 100                                                    _candidates->push_back(SP_ITEM(o));
 101                                                    break;
 102                                                 }
 103                                         }
 104                                 }
 105                             }
 106                         }
 107                     }
 108                 }
 109         }
 110     }
 111 }
 112
 113
 114 void Inkscape::ObjectSnapper::_snapNodes(Inkscape::Snapper::PointType const &t,
 115                                                                                  Inkscape::SnappedPoint &s,
 116                                          NR::Point const &p,
 117                                          bool const &first_point,
 118                                          DimensionToSnap const snap_dim) const
 119 {
 120     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 121     ** in SPDesktop rather than SPNamedView?
 122     */
 123     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 124
 125     // Determine the type of bounding box we should snap to
 126     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 127         if (_snap_to_bboxnode) {
 128                 gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 129                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 130         }
 131
 132         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 133         bool p_is_a_bbox = t & Inkscape::Snapper::SNAPPOINT_BBOX;
 134         bool p_is_a_guide = t & Inkscape::Snapper::SNAPPOINT_GUIDE;
 135
 136         // A point considered for snapping should be either a node, a bbox corner or a guide. Pick only ONE!
 137         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));
 138
 139     // Now, let's first collect all points to snap to. If we have a whole bunch of points to snap,
 140     // e.g. when translating an item using the selector tool, then we will only do this for the
 141     // first point and store the collection for later use. This dramatically improves the performance
 142         if (first_point) {
 143                 _points_to_snap_to->clear();
 144             for (std::list<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
 145
 146                 NR::Matrix i2doc(NR::identity());
 147                 SPItem *root_item = NULL;
 148                 if (SP_IS_USE(*i)) {
 149                     i2doc = sp_use_get_root_transform(SP_USE(*i));
 150                     root_item = sp_use_root(SP_USE(*i));
 151                 } else {
 152                     i2doc = sp_item_i2doc_affine(*i);
 153                     root_item = *i;
 154                 }
 155
 156                 SPCurve *curve = NULL;
 157
 158                 if (SP_IS_SHAPE(root_item)) {
 159                     SPShape const *sh = SP_SHAPE(root_item);
 160                     curve = sh->curve;
 161                 } else if (SP_IS_IMAGE(root_item)) {
 162                     SPImage const *im = SP_IMAGE(root_item);
 163                     curve = im->curve;
 164                 }
 165
 166                         //Collect all nodes so we can snap to them
 167                 if (_snap_to_itemnode) {
 168                         if (!(_strict_snapping && !p_is_a_node) || p_is_a_guide) {
 169                                 if (curve) {
 170                                     int j = 0;
 171                                     while (SP_CURVE_BPATH(curve)[j].code != NR_END) {
 172                                         /* Get this node in desktop coordinates */
 173                                         NArtBpath const &bp = SP_CURVE_BPATH(curve)[j];
 174                                         _points_to_snap_to->push_back(desktop->doc2dt(bp.c(3) * i2doc));
 175                                         j++;
 176                                     }
 177                                     if (_include_item_center) {
 178                                         _points_to_snap_to->push_back(root_item->getCenter());
 179                                     }
 180                                 }
 181                         }
 182                 }
 183
 184                 //Collect the bounding box's corners so we can snap to them
 185                 if (_snap_to_bboxnode) {
 186                         if (!(_strict_snapping && !p_is_a_bbox) || p_is_a_guide) {
 187                                 NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(root_item, bbox_type);
 188                                 if (b) {
 189                                         for ( unsigned k = 0 ; k < 4 ; k++ ) {
 190                                             _points_to_snap_to->push_back(b->corner(k));
 191                                         }
 192                                 }
 193                         }
 194                 }
 195             }
 196         }
 197
 198     //Do the snapping, using all the nodes and corners collected above
 199     for (std::list<NR::Point>::const_iterator k = _points_to_snap_to->begin(); k != _points_to_snap_to->end(); k++) {
 200             /* Try to snap to this node of the path */
 201         NR::Coord dist = NR_HUGE;
 202         NR::Point snapped_point;
 203         switch (snap_dim) {
 204                 case SNAP_X:
 205                         dist = fabs((*k)[NR::X] - p[NR::X]);
 206                         snapped_point = NR::Point((*k)[NR::X], p[NR::Y]);
 207                         break;
 208                 case SNAP_Y:
 209                         dist = fabs((*k)[NR::Y] - p[NR::Y]);
 210                         snapped_point = NR::Point(p[NR::X], (*k)[NR::Y]);
 211                         break;
 212                 case SNAP_XY:
 213                         dist = NR::L2(*k - p);
 214                         snapped_point = *k;
 215                         break;
 216         }
 217         if (dist < getDistance() && dist < s.getDistance()) {
 218             s = SnappedPoint(snapped_point, dist);
 219         }
 220     }
 221 }
 222
 223
 224 void Inkscape::ObjectSnapper::_snapPaths(Inkscape::Snapper::PointType const &t,
 225                                                                                  Inkscape::SnappedPoint &s,
 226                                          NR::Point const &p,
 227                                          bool const &first_point) const
 228 {
 229     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 230     ** in SPDesktop rather than SPNamedView?
 231     */
 232     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 233
 234     NR::Point const p_doc = desktop->dt2doc(p);
 235
 236     // Determine the type of bounding box we should snap to
 237     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 238         if (_snap_to_bboxpath) {
 239         gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 240                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 241         }
 242
 243         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 244
 245     // Now, let's first collect all paths to snap to. If we have a whole bunch of points to snap,
 246     // e.g. when translating an item using the selector tool, then we will only do this for the
 247     // first point and store the collection for later use. This dramatically improves the performance
 248     if (first_point) {
 249             for (std::list<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
 250                 delete *k;
 251             }
 252             _paths_to_snap_to->clear();
 253             for (std::list<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
 254
 255                 /* Transform the requested snap point to this item's coordinates */
 256                 NR::Matrix i2doc(NR::identity());
 257                 SPItem *root_item = NULL;
 258                 /* We might have a clone at hand, so make sure we get the root item */
 259                 if (SP_IS_USE(*i)) {
 260                     i2doc = sp_use_get_root_transform(SP_USE(*i));
 261                     root_item = sp_use_root(SP_USE(*i));
 262                 } else {
 263                     i2doc = sp_item_i2doc_affine(*i);
 264                     root_item = *i;
 265                 }
 266
 267                 //Build a list of all paths considered for snapping to
 268
 269                 //Add the item's path to snap to
 270                 if (_snap_to_itempath) {
 271                         if (!(_strict_snapping && !p_is_a_node)) {
 272                                 _paths_to_snap_to->push_back(Path_for_item(root_item, true, true));
 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::list<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                     }
 319                 }
 320         }
 321     }
 322 }
 323
 324
 325 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doFreeSnap(Inkscape::Snapper::PointType const &t,
 326                                                                                                                         NR::Point const &p,
 327                                                                                                                         bool const &first_point,
 328                                                                         std::vector<NR::Point> &points_to_snap,
 329                                                             std::list<SPItem const *> const &it) const
 330 {
 331     if ( NULL == _named_view ) {
 332         return SnappedPoint(p, NR_HUGE);
 333     }
 334
 335             /* Get a list of all the SPItems that we will try to snap to */
 336     _findCandidates(sp_document_root(_named_view->document), it, first_point, points_to_snap, SNAP_XY);
 337
 338         SnappedPoint s(p, NR_HUGE);
 339
 340     if (_snap_to_itemnode || _snap_to_bboxnode) {
 341         _snapNodes(t, s, p, first_point, SNAP_XY);
 342     }
 343     if (_snap_to_itempath || _snap_to_bboxpath) {
 344         _snapPaths(t, s, p, first_point);
 345     }
 346
 347     return s;
 348 }
 349
 350
 351
 352 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doConstrainedSnap(Inkscape::Snapper::PointType const &t,
 353                                                                                                                                    NR::Point const &p,
 354                                                                                                                                    bool const &first_point,
 355                                                                                    std::vector<NR::Point> &points_to_snap,
 356                                                                    ConstraintLine const &c,
 357                                                                    std::list<SPItem const *> const &it) const
 358 {
 359     /* FIXME: this needs implementing properly; I think we have to do the
 360     ** intersection of c with the objects.
 361     */
 362     return _doFreeSnap(t, p, first_point, points_to_snap, it);
 363 }
 364
 365
 366
 367 Inkscape::SnappedPoint Inkscape::ObjectSnapper::guideSnap(NR::Point const &p,
 368                                                                                                                   DimensionToSnap const snap_dim) const
 369 {
 370     if ( NULL == _named_view ) {
 371         return SnappedPoint(p, NR_HUGE);
 372     }
 373
 374     /* Get a list of all the SPItems that we will try to snap to */
 375     std::list<SPItem*> cand;
 376     std::list<SPItem const *> const it; //just an empty list
 377
 378     std::vector<NR::Point> points_to_snap;
 379     points_to_snap.push_back(p);
 380
 381     _findCandidates(sp_document_root(_named_view->document), it, true, points_to_snap, snap_dim);
 382
 383     SnappedPoint s(p, NR_HUGE);
 384     _snapNodes(Inkscape::Snapper::SNAPPOINT_GUIDE, s, p, true, snap_dim);
 385
 386     return s;
 387 }
 388
 389 /**
 390  *  \return true if this Snapper will snap at least one kind of point.
 391  */
 392 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
 393 {
 394     bool snap_to_something = _snap_to_itempath || _snap_to_itemnode || _snap_to_bboxpath || _snap_to_bboxnode;
 395     return (_enabled && _snap_from != 0 && snap_to_something);
 396 }
 397
 398
 399 /*
 400   Local Variables:
 401   mode:c++
 402   c-file-style:"stroustrup"
 403   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 404   indent-tabs-mode:nil
 405   fill-column:99
 406   End:
 407 */
 408 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :