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-path.h"
  18 #include "sp-image.h"
  19 #include "sp-item-group.h"
  20 #include "sp-item.h"
  21 #include "sp-use.h"
  22 #include "display/curve.h"
  23 #include "desktop.h"
  24 #include "inkscape.h"
  25 #include "splivarot.h"
  26 #include "prefs-utils.h"
  27
  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 {
  33
  34 }
  35
  36
  37 /**
  38  *  \param p Point we are trying to snap (desktop coordinates)
  39  */
  40
  41 void Inkscape::ObjectSnapper::_findCandidates(std::list<SPItem*>& c,
  42                                               SPObject* r,
  43                                               std::list<SPItem const *> const &it,
  44                                               NR::Point const &p) const
  45 {
  46     if (ThisSnapperMightSnap()) {
  47         SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  48         for (SPObject* o = sp_object_first_child(r); o != NULL; o = SP_OBJECT_NEXT(o)) {
  49             if (SP_IS_ITEM(o) && !SP_ITEM(o)->isLocked() && !desktop->itemIsHidden(SP_ITEM(o))) {
  50
  51                 /* See if this item is on the ignore list */
  52                 std::list<SPItem const *>::const_iterator i = it.begin();
  53                 while (i != it.end() && *i != o) {
  54                     i++;
  55                 }
  56
  57                 if (i == it.end()) {
  58                     /* See if the item is within range */
  59                     if (SP_IS_GROUP(o)) {
  60                         _findCandidates(c, o, it, p);
  61                     } else {
  62                         NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(SP_ITEM(o));
  63                         if ( b && NR::expand(*b, -getDistance()).contains(p) ) {
  64                             c.push_back(SP_ITEM(o));
  65                         }
  66                     }
  67                 }
  68
  69             }
  70         }
  71     }
  72 }
  73
  74
  75 void Inkscape::ObjectSnapper::_snapNodes(Inkscape::Snapper::PointType const &t,
  76                                                                                  Inkscape::SnappedPoint &s,
  77                                          NR::Point const &p,
  78                                          std::list<SPItem*> const &cand) const
  79 {
  80     /* FIXME: this seems like a hack.  Perhaps Snappers should be
  81     ** in SPDesktop rather than SPNamedView?
  82     */
  83     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  84
  85     // Determine the type of bounding box we should snap to
  86     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
  87         if (_snap_to_bboxnode) {
  88                 gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
  89                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
  90         }
  91
  92         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
  93
  94     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
  95
  96         NR::Matrix i2doc(NR::identity());
  97         SPItem *root_item = NULL;
  98         if (SP_IS_USE(*i)) {
  99             i2doc = sp_use_get_root_transform(SP_USE(*i));
 100             root_item = sp_use_root(SP_USE(*i));
 101         } else {
 102             i2doc = sp_item_i2doc_affine(*i);
 103             root_item = *i;
 104         }
 105
 106         SPCurve *curve = NULL;
 107
 108         if (SP_IS_SHAPE(root_item)) {
 109             SPShape const *sh = SP_SHAPE(root_item);
 110             curve = sh->curve;
 111         } else if (SP_IS_IMAGE(root_item)) {
 112             SPImage const *im = SP_IMAGE(root_item);
 113             curve = im->curve;
 114         }
 115
 116                 std::list<NR::Point> points_to_snap_to;
 117
 118         //Collect all nodes so we can snap to them
 119         if (_snap_to_itemnode) {
 120                 if (!(_strict_snapping && !p_is_a_node)) {
 121                         if (curve) {
 122                             int j = 0;
 123                             while (SP_CURVE_BPATH(curve)[j].code != NR_END) {
 124                                 /* Get this node in desktop coordinates */
 125                                 NArtBpath const &bp = SP_CURVE_BPATH(curve)[j];
 126                                 points_to_snap_to.push_back(desktop->doc2dt(bp.c(3) * i2doc));
 127                                 j++;
 128                             }
 129                         }
 130                 }
 131         }
 132
 133         //Collect the bounding box's corners so we can snap to them
 134         if (_snap_to_bboxnode) {
 135                 if (!(_strict_snapping && p_is_a_node)) {
 136                         NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(root_item, bbox_type);
 137                         if (b) {
 138                                 for ( unsigned k = 0 ; k < 4 ; k++ ) {
 139                                     points_to_snap_to.push_back(b->corner(k));
 140                                 }
 141                         }
 142                 }
 143         }
 144
 145         //Do the snapping, using all the nodes and corners collected above
 146         for (std::list<NR::Point>::const_iterator k = points_to_snap_to.begin(); k != points_to_snap_to.end(); k++) {
 147             /* Try to snap to this node of the path */
 148             NR::Coord const dist = NR::L2(*k - p);
 149             if (dist < getDistance() && dist < s.getDistance()) {
 150                 s = SnappedPoint(*k, dist);
 151             }
 152         }
 153     }
 154 }
 155
 156
 157 void Inkscape::ObjectSnapper::_snapPaths(Inkscape::Snapper::PointType const &t,
 158                                                                                  Inkscape::SnappedPoint &s,
 159                                          NR::Point const &p,
 160                                          std::list<SPItem*> const &cand) const
 161 {
 162     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 163     ** in SPDesktop rather than SPNamedView?
 164     */
 165     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 166
 167     NR::Point const p_doc = desktop->dt2doc(p);
 168
 169     // Determine the type of bounding box we should snap to
 170     SPItem::BBoxType bbox_type = SPItem::GEOMETRIC_BBOX;
 171         if (_snap_to_bboxpath) {
 172         gchar const *prefs_bbox = prefs_get_string_attribute("tools.select", "bounding_box");
 173                 bbox_type = (prefs_bbox != NULL && strcmp(prefs_bbox, "geometric")==0)? SPItem::GEOMETRIC_BBOX : SPItem::APPROXIMATE_BBOX;
 174         }
 175
 176         bool p_is_a_node = t & Inkscape::Snapper::SNAPPOINT_NODE;
 177
 178     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
 179
 180         /* Transform the requested snap point to this item's coordinates */
 181         NR::Matrix i2doc(NR::identity());
 182         SPItem *root_item = NULL;
 183         /* We might have a clone at hand, so make sure we get the root item */
 184         if (SP_IS_USE(*i)) {
 185             i2doc = sp_use_get_root_transform(SP_USE(*i));
 186             root_item = sp_use_root(SP_USE(*i));
 187         } else {
 188             i2doc = sp_item_i2doc_affine(*i);
 189             root_item = *i;
 190         }
 191
 192         //Build a list of all paths considered for snapping to
 193         std::list<Path*> paths_to_snap_to;
 194
 195         //Add the item's path to snap to
 196         if (_snap_to_itempath) {
 197                 if (!(_strict_snapping && !p_is_a_node)) {
 198                         paths_to_snap_to.push_back(Path_for_item(root_item, true, true));
 199                 }
 200         }
 201
 202         //Add the item's bounding box to snap to
 203         if (_snap_to_bboxpath) {
 204                 if (!(_strict_snapping && p_is_a_node)) {
 205                         //This will get ugly... rect -> curve -> bpath
 206                         NRRect rect;
 207                         sp_item_invoke_bbox(root_item, &rect, i2doc, TRUE, bbox_type);
 208                         NR::Maybe<NR::Rect> bbox = rect.upgrade();
 209                         SPCurve *curve = sp_curve_new_from_rect(bbox);
 210                         NArtBpath *bpath = SP_CURVE_BPATH(curve);
 211                         Path *path = bpath_to_Path(bpath);
 212                         paths_to_snap_to.push_back(path);
 213                         delete curve;
 214                         delete bpath;
 215                 }
 216         }
 217
 218         //Now we can finally do the real snapping, using the paths collected above
 219         for (std::list<Path*>::const_iterator k = paths_to_snap_to.begin(); k != paths_to_snap_to.end(); k++) {
 220                 if (*k) {
 221                     (*k)->ConvertWithBackData(0.01);
 222
 223                         /* Look for the nearest position on this SPItem to our snap point */
 224                         NR::Maybe<Path::cut_position> const o = get_nearest_position_on_Path(*k, p_doc);
 225                         if (o && o->t >= 0 && o->t <= 1) {
 226
 227                             /* Convert the nearest point back to desktop coordinates */
 228                             NR::Point const o_it = get_point_on_Path(*k, o->piece, o->t);
 229                             NR::Point const o_dt = desktop->doc2dt(o_it);
 230
 231                             NR::Coord const dist = NR::L2(o_dt - p);
 232                             if (dist < getDistance() && dist < s.getDistance()) {
 233                                 s = SnappedPoint(o_dt, dist);
 234                             }
 235                         }
 236
 237                         delete *k;
 238                 }
 239             }
 240     }
 241 }
 242
 243
 244 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doFreeSnap(Inkscape::Snapper::PointType const &t,
 245                                                                                                                         NR::Point const &p,
 246                                                             std::list<SPItem const *> const &it) const
 247 {
 248     if ( NULL == _named_view ) {
 249         return SnappedPoint(p, NR_HUGE);
 250     }
 251
 252     /* Get a list of all the SPItems that we will try to snap to */
 253     std::list<SPItem*> cand;
 254     _findCandidates(cand, sp_document_root(_named_view->document), it, p);
 255
 256     SnappedPoint s(p, NR_HUGE);
 257
 258     if (_snap_to_itemnode || _snap_to_bboxnode) {
 259         _snapNodes(t, s, p, cand);
 260     }
 261     if (_snap_to_itempath || _snap_to_bboxpath) {
 262         _snapPaths(t, s, p, cand);
 263     }
 264
 265     return s;
 266 }
 267
 268
 269
 270 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doConstrainedSnap(Inkscape::Snapper::PointType const &t,
 271                                                                                                                                    NR::Point const &p,
 272                                                                    ConstraintLine const &c,
 273                                                                    std::list<SPItem const *> const &it) const
 274 {
 275     /* FIXME: this needs implementing properly; I think we have to do the
 276     ** intersection of c with the objects.
 277     */
 278     return _doFreeSnap(t, p, it);
 279 }
 280
 281 /**
 282  *  \return true if this Snapper will snap at least one kind of point.
 283  */
 284 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
 285 {
 286     bool snap_to_something = _snap_to_itempath || _snap_to_itemnode || _snap_to_bboxpath || _snap_to_bboxnode;
 287     return (_enabled && _snap_from != 0 && snap_to_something);
 288 }
 289
 290
 291 /*
 292   Local Variables:
 293   mode:c++
 294   c-file-style:"stroustrup"
 295   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 296   indent-tabs-mode:nil
 297   fill-column:99
 298   End:
 299 */
 300 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :