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::list<SPItem*>;
  35         _points_to_snap_to = new std::list<NR::Point>;
  36         _paths_to_snap_to = new std::list<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::list<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 void 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     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 123     ** in SPDesktop rather than SPNamedView?
 124     */
 125     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 126
 127     // Determine the type of bounding box we should snap to
 128     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 129         if (_snap_to_bboxnode) {
 130                 gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 131                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 132         }
 133
 134         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 135         bool p_is_a_bbox = t & Inkscape::Snapper::SNAPPOINT_BBOX;
 136         bool p_is_a_guide = t & Inkscape::Snapper::SNAPPOINT_GUIDE;
 137
 138         // A point considered for snapping should be either a node, a bbox corner or a guide. Pick only ONE!
 139         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));
 140
 141     // Now, let's first collect all points to snap to. If we have a whole bunch of points to snap,
 142     // e.g. when translating an item using the selector tool, then we will only do this for the
 143     // first point and store the collection for later use. This dramatically improves the performance
 144         if (first_point) {
 145                 _points_to_snap_to->clear();
 146             for (std::list<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
 147
 148                 NR::Matrix i2doc(NR::identity());
 149                 SPItem *root_item = NULL;
 150                 if (SP_IS_USE(*i)) {
 151                     i2doc = sp_use_get_root_transform(SP_USE(*i));
 152                     root_item = sp_use_root(SP_USE(*i));
 153                 } else {
 154                     i2doc = sp_item_i2doc_affine(*i);
 155                     root_item = *i;
 156                 }
 157
 158                 SPCurve *curve = NULL;
 159
 160                 if (SP_IS_SHAPE(root_item)) {
 161                     SPShape const *sh = SP_SHAPE(root_item);
 162                     curve = sh->curve;
 163                 } else if (SP_IS_IMAGE(root_item)) {
 164                     SPImage const *im = SP_IMAGE(root_item);
 165                     curve = im->curve;
 166                 }
 167
 168                         //Collect all nodes so we can snap to them
 169                 if (_snap_to_itemnode) {
 170                         if (!(_strict_snapping && !p_is_a_node) || p_is_a_guide) {
 171                                 if (curve) {
 172                                     int j = 0;
 173                                     while (SP_CURVE_BPATH(curve)[j].code != NR_END) {
 174                                         /* Get this node in desktop coordinates */
 175                                         NArtBpath const &bp = SP_CURVE_BPATH(curve)[j];
 176                                         _points_to_snap_to->push_back(desktop->doc2dt(bp.c(3) * i2doc));
 177                                         j++;
 178                                     }
 179                                     if (_include_item_center) {
 180                                         _points_to_snap_to->push_back(root_item->getCenter());
 181                                     }
 182                                 }
 183                         }
 184                 }
 185
 186                 //Collect the bounding box's corners so we can snap to them
 187                 if (_snap_to_bboxnode) {
 188                         if (!(_strict_snapping && !p_is_a_bbox) || p_is_a_guide) {
 189                                 NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(root_item, bbox_type);
 190                                 if (b) {
 191                                         for ( unsigned k = 0 ; k < 4 ; k++ ) {
 192                                             _points_to_snap_to->push_back(b->corner(k));
 193                                         }
 194                                 }
 195                         }
 196                 }
 197             }
 198         }
 199
 200     //Do the snapping, using all the nodes and corners collected above
 201     for (std::list<NR::Point>::const_iterator k = _points_to_snap_to->begin(); k != _points_to_snap_to->end(); k++) {
 202             /* Try to snap to this node of the path */
 203         NR::Coord dist = NR_HUGE;
 204         NR::Point snapped_point;
 205         switch (snap_dim) {
 206                 case SNAP_X:
 207                         dist = fabs((*k)[NR::X] - p[NR::X]);
 208                         snapped_point = NR::Point((*k)[NR::X], p[NR::Y]);
 209                         break;
 210                 case SNAP_Y:
 211                         dist = fabs((*k)[NR::Y] - p[NR::Y]);
 212                         snapped_point = NR::Point(p[NR::X], (*k)[NR::Y]);
 213                         break;
 214                 case SNAP_XY:
 215                         dist = NR::L2(*k - p);
 216                         snapped_point = *k;
 217                         break;
 218         }
 219         if (dist < getDistance() && dist < s.getDistance()) {
 220             s = SnappedPoint(snapped_point, dist);
 221         }
 222     }
 223 }
 224
 225
 226 void Inkscape::ObjectSnapper::_snapPaths(Inkscape::Snapper::PointType const &t,
 227                                                                                  Inkscape::SnappedPoint &s,
 228                                          NR::Point const &p,
 229                                          bool const &first_point) const
 230 {
 231     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 232     ** in SPDesktop rather than SPNamedView?
 233     */
 234     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 235
 236     NR::Point const p_doc = desktop->dt2doc(p);
 237
 238     // Determine the type of bounding box we should snap to
 239     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 240         if (_snap_to_bboxpath) {
 241         gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 242                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 243         }
 244
 245         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 246
 247     // Now, let's first collect all paths to snap to. If we have a whole bunch of points to snap,
 248     // e.g. when translating an item using the selector tool, then we will only do this for the
 249     // first point and store the collection for later use. This dramatically improves the performance
 250     if (first_point) {
 251             for (std::list<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
 252                 delete *k;
 253             }
 254             _paths_to_snap_to->clear();
 255             for (std::list<SPItem*>::const_iterator i = _candidates->begin(); i != _candidates->end(); i++) {
 256
 257                 /* Transform the requested snap point to this item's coordinates */
 258                 NR::Matrix i2doc(NR::identity());
 259                 SPItem *root_item = NULL;
 260                 /* We might have a clone at hand, so make sure we get the root item */
 261                 if (SP_IS_USE(*i)) {
 262                     i2doc = sp_use_get_root_transform(SP_USE(*i));
 263                     root_item = sp_use_root(SP_USE(*i));
 264                 } else {
 265                     i2doc = sp_item_i2doc_affine(*i);
 266                     root_item = *i;
 267                 }
 268
 269                 //Build a list of all paths considered for snapping to
 270
 271                 //Add the item's path to snap to
 272                 if (_snap_to_itempath) {
 273                         if (!(_strict_snapping && !p_is_a_node)) {
 274                                 // Snapping to the path of characters is very cool, but for a large
 275                                         // chunk of text this will take ages! So limit snapping to text paths
 276                                         // containing max. 240 characters. Snapping the bbox will not be affected
 277                                         bool very_lenghty_prose = false;
 278                                         if (SP_IS_TEXT(root_item) || SP_IS_FLOWTEXT(root_item)) {
 279                                                 very_lenghty_prose =  sp_text_get_length(SP_TEXT(root_item)) > 240;
 280                                         }
 281
 282                                         // On my AMD 3000+, the snapping lag becomes annoying at approx. 240 chars
 283                                         // which corresponds to a lag of 500 msec. This is for snapping a rect
 284                                         // to a single line of text.
 285
 286                                         // Snapping for example to a traced bitmap is also very stressing for
 287                                         // the CPU, so we'll only snap to paths having no more than 500 nodes
 288                                         // This also leads to a lag of approx. 500 msec (in my lousy test set-up).
 289                                         bool very_complex_path = false;
 290                                         if (SP_IS_PATH(root_item)) {
 291                                                 very_complex_path = sp_nodes_in_path(SP_PATH(root_item)) > 500;
 292                                         }
 293
 294                                         if (!very_lenghty_prose && !very_complex_path) {
 295                                         _paths_to_snap_to->push_back(Path_for_item(root_item, true, true));
 296                                         }
 297                         }
 298                 }
 299
 300                 //Add the item's bounding box to snap to
 301                 if (_snap_to_bboxpath) {
 302                         if (!(_strict_snapping && p_is_a_node)) {
 303                                 //This will get ugly... rect -> curve -> bpath
 304                                 NRRect rect;
 305                                 sp_item_invoke_bbox(root_item, &rect, i2doc, TRUE, bbox_type);
 306                                 NR::Maybe<NR::Rect> bbox = rect.upgrade();
 307                                 SPCurve *curve = sp_curve_new_from_rect(bbox);
 308                                 if (curve) {
 309                                         NArtBpath *bpath = SP_CURVE_BPATH(curve);
 310                                         if (bpath) {
 311                                                 Path *path = bpath_to_Path(bpath);
 312                                                 if (path) {
 313                                                         _paths_to_snap_to->push_back(path);
 314                                                 }
 315                                                 delete bpath;
 316                                         }
 317                                         delete curve;
 318                                 }
 319                         }
 320                 }
 321             }
 322     }
 323
 324     //Now we can finally do the real snapping, using the paths collected above
 325     for (std::list<Path*>::const_iterator k = _paths_to_snap_to->begin(); k != _paths_to_snap_to->end(); k++) {
 326         if (*k) {
 327             if (first_point) {
 328                 (*k)->ConvertWithBackData(0.01); //This is extremely time consuming!
 329             }
 330
 331                 /* Look for the nearest position on this SPItem to our snap point */
 332                 NR::Maybe<Path::cut_position> const o = get_nearest_position_on_Path(*k, p_doc);
 333                 if (o && o->t >= 0 && o->t <= 1) {
 334
 335                     /* Convert the nearest point back to desktop coordinates */
 336                     NR::Point const o_it = get_point_on_Path(*k, o->piece, o->t);
 337                     NR::Point const o_dt = desktop->doc2dt(o_it);
 338
 339                     NR::Coord const dist = NR::L2(o_dt - p);
 340                     if (dist < getDistance() && dist < s.getDistance()) {
 341                         s = SnappedPoint(o_dt, dist);
 342                     }
 343                 }
 344         }
 345     }
 346 }
 347
 348
 349 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doFreeSnap(Inkscape::Snapper::PointType const &t,
 350                                                                                                                         NR::Point const &p,
 351                                                                                                                         bool const &first_point,
 352                                                                         std::vector<NR::Point> &points_to_snap,
 353                                                             std::list<SPItem const *> const &it) const
 354 {
 355     if ( NULL == _named_view ) {
 356         return SnappedPoint(p, NR_HUGE);
 357     }
 358
 359     /* Get a list of all the SPItems that we will try to snap to */
 360         if (first_point) {
 361                 _findCandidates(sp_document_root(_named_view->document), it, first_point, points_to_snap, SNAP_XY);
 362         }
 363
 364         SnappedPoint s(p, NR_HUGE);
 365
 366     if (_snap_to_itemnode || _snap_to_bboxnode) {
 367         _snapNodes(t, s, p, first_point, SNAP_XY);
 368     }
 369     if (_snap_to_itempath || _snap_to_bboxpath) {
 370         _snapPaths(t, s, p, first_point);
 371     }
 372
 373     return s;
 374 }
 375
 376
 377
 378 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doConstrainedSnap(Inkscape::Snapper::PointType const &t,
 379                                                                                                                                    NR::Point const &p,
 380                                                                                                                                    bool const &first_point,
 381                                                                                    std::vector<NR::Point> &points_to_snap,
 382                                                                    ConstraintLine const &c,
 383                                                                    std::list<SPItem const *> const &it) const
 384 {
 385     /* FIXME: this needs implementing properly; I think we have to do the
 386     ** intersection of c with the objects.
 387     */
 388     return _doFreeSnap(t, p, first_point, points_to_snap, it);
 389 }
 390
 391
 392
 393 Inkscape::SnappedPoint Inkscape::ObjectSnapper::guideSnap(NR::Point const &p,
 394                                                                                                                   DimensionToSnap const snap_dim) const
 395 {
 396     if ( NULL == _named_view ) {
 397         return SnappedPoint(p, NR_HUGE);
 398     }
 399
 400     /* Get a list of all the SPItems that we will try to snap to */
 401     std::list<SPItem*> cand;
 402     std::list<SPItem const *> const it; //just an empty list
 403
 404     std::vector<NR::Point> points_to_snap;
 405     points_to_snap.push_back(p);
 406
 407     _findCandidates(sp_document_root(_named_view->document), it, true, points_to_snap, snap_dim);
 408
 409     SnappedPoint s(p, NR_HUGE);
 410     _snapNodes(Inkscape::Snapper::SNAPPOINT_GUIDE, s, p, true, snap_dim);
 411
 412     return s;
 413 }
 414
 415 /**
 416  *  \return true if this Snapper will snap at least one kind of point.
 417  */
 418 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
 419 {
 420     bool snap_to_something = _snap_to_itempath || _snap_to_itemnode || _snap_to_bboxpath || _snap_to_bboxnode;
 421     return (_enabled && _snap_from != 0 && snap_to_something);
 422 }
 423
 424
 425 /*
 426   Local Variables:
 427   mode:c++
 428   c-file-style:"stroustrup"
 429   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 430   indent-tabs-mode:nil
 431   fill-column:99
 432   End:
 433 */
 434 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :