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-item-group.h"
  19 #include "sp-use.h"
  20 #include "display/curve.h"
  21 #include "desktop.h"
  22 #include "inkscape.h"
  23 #include "splivarot.h"
  24
  25
  26 Inkscape::ObjectSnapper::ObjectSnapper(SPNamedView const *nv, NR::Coord const d)
  27     : Snapper(nv, d), _snap_to_nodes(true), _snap_to_paths(true)
  28 {
  29
  30 }
  31
  32
  33 /**
  34  *  \param p Point we are trying to snap (desktop coordinates)
  35  */
  36
  37 void Inkscape::ObjectSnapper::_findCandidates(std::list<SPItem*>& c,
  38                                               SPObject* r,
  39                                               std::list<SPItem const *> const &it,
  40                                               NR::Point const &p) const
  41 {
  42     if (ThisSnapperMightSnap()) {
  43         SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  44         for (SPObject* o = sp_object_first_child(r); o != NULL; o = SP_OBJECT_NEXT(o)) {
  45             if (SP_IS_ITEM(o) && !SP_ITEM(o)->isLocked() && !desktop->itemIsHidden(SP_ITEM(o))) {
  46
  47                 /* See if this item is on the ignore list */
  48                 std::list<SPItem const *>::const_iterator i = it.begin();
  49                 while (i != it.end() && *i != o) {
  50                     i++;
  51                 }
  52
  53                 if (i == it.end()) {
  54                     /* See if the item is within range */
  55                     if (SP_IS_GROUP(o)) {
  56                         _findCandidates(c, o, it, p);
  57                     } else {
  58                         NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(SP_ITEM(o));
  59                         if ( b && NR::expand(*b, -getDistance()).contains(p) ) {
  60                             c.push_back(SP_ITEM(o));
  61                         }
  62                     }
  63                 }
  64
  65             }
  66         }
  67     }
  68 }
  69
  70
  71 void Inkscape::ObjectSnapper::_snapNodes(Inkscape::SnappedPoint &s,
  72                                          NR::Point const &p,
  73                                          std::list<SPItem*> const &cand) const
  74 {
  75     /* FIXME: this seems like a hack.  Perhaps Snappers should be
  76     ** in SPDesktop rather than SPNamedView?
  77     */
  78     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  79
  80     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
  81
  82         NR::Matrix i2doc(NR::identity());
  83         SPItem *root_item = NULL;
  84         if (SP_IS_USE(*i)) {
  85             i2doc = sp_use_get_root_transform(SP_USE(*i));
  86             root_item = sp_use_root(SP_USE(*i));
  87         } else {
  88             i2doc = sp_item_i2doc_affine(*i);
  89             root_item = *i;
  90         }
  91
  92         if (SP_IS_SHAPE(root_item)) {
  93
  94             SPShape const *sh = SP_SHAPE(root_item);
  95             if (sh->curve) {
  96
  97                 int j = 0;
  98
  99                 while (SP_CURVE_BPATH(sh->curve)[j].code != NR_END) {
 100
 101                     /* Get this node in desktop coordinates */
 102                     NArtBpath const &bp = SP_CURVE_BPATH(sh->curve)[j];
 103                     NR::Point const n = desktop->doc2dt(bp.c(3) * i2doc);
 104
 105                     /* Try to snap to this node of the path */
 106                     NR::Coord const dist = NR::L2(n - p);
 107                     if (dist < getDistance() && dist < s.getDistance()) {
 108                         s = SnappedPoint(n, dist);
 109                     }
 110
 111                     j++;
 112                 }
 113             }
 114         }
 115     }
 116 }
 117
 118
 119 void Inkscape::ObjectSnapper::_snapPaths(Inkscape::SnappedPoint &s,
 120                                          NR::Point const &p,
 121                                          std::list<SPItem*> const &cand) const
 122 {
 123     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 124     ** in SPDesktop rather than SPNamedView?
 125     */
 126     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 127
 128     NR::Point const p_doc = desktop->dt2doc(p);
 129
 130     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
 131
 132         /* Transform the requested snap point to this item's coordinates */
 133         NR::Matrix i2doc(NR::identity());
 134         SPItem *root_item = NULL;
 135         /* We might have a clone at hand, so make sure we get the root item */
 136         if (SP_IS_USE(*i)) {
 137             i2doc = sp_use_get_root_transform(SP_USE(*i));
 138             root_item = sp_use_root(SP_USE(*i));
 139         } else {
 140             i2doc = sp_item_i2doc_affine(*i);
 141             root_item = *i;
 142         }
 143
 144         NR::Point const p_it = p_doc * i2doc.inverse();
 145
 146         Path *livarot_path = Path_for_item(root_item, false, false);
 147         if (!livarot_path)
 148             continue;
 149
 150         livarot_path->ConvertWithBackData(0.01);
 151
 152         /* Look for the nearest position on this SPItem to our snap point */
 153         NR::Maybe<Path::cut_position> const o = get_nearest_position_on_Path(livarot_path, p_it);
 154         if (o && o->t >= 0 && o->t <= 1) {
 155
 156             /* Convert the nearest point back to desktop coordinates */
 157             NR::Point const o_it = get_point_on_Path(livarot_path, o->piece, o->t);
 158             NR::Point const o_dt = desktop->doc2dt(o_it * i2doc);
 159
 160             NR::Coord const dist = NR::L2(o_dt - p);
 161             if (dist < getDistance() && dist < s.getDistance()) {
 162                 s = SnappedPoint(o_dt, dist);
 163             }
 164         }
 165
 166         delete livarot_path;
 167     }
 168 }
 169
 170
 171 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doFreeSnap(NR::Point const &p,
 172                                                             std::list<SPItem const *> const &it) const
 173 {
 174     if ( NULL == _named_view ) {
 175         return SnappedPoint(p, NR_HUGE);
 176     }
 177
 178     /* Get a list of all the SPItems that we will try to snap to */
 179     std::list<SPItem*> cand;
 180     _findCandidates(cand, sp_document_root(_named_view->document), it, p);
 181
 182     SnappedPoint s(p, NR_HUGE);
 183
 184     if (_snap_to_nodes) {
 185         _snapNodes(s, p, cand);
 186     }
 187     if (_snap_to_paths) {
 188         _snapPaths(s, p, cand);
 189     }
 190
 191     return s;
 192 }
 193
 194
 195
 196 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doConstrainedSnap(NR::Point const &p,
 197                                                                    ConstraintLine const &c,
 198                                                                    std::list<SPItem const *> const &it) const
 199 {
 200     /* FIXME: this needs implementing properly; I think we have to do the
 201     ** intersection of c with the objects.
 202     */
 203     return _doFreeSnap(p, it);
 204 }
 205
 206 /**
 207  *  \return true if this Snapper will snap at least one kind of point.
 208  */
 209 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
 210 {
 211     return (_enabled && _snap_to != 0 && (_snap_to_paths || _snap_to_nodes));
 212 }
 213
 214
 215 /*
 216   Local Variables:
 217   mode:c++
 218   c-file-style:"stroustrup"
 219   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 220   indent-tabs-mode:nil
 221   fill-column:99
 222   End:
 223 */
 224 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :