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 "display/curve.h"
  19 #include "desktop.h"
  20 #include "inkscape.h"
  21 #include "splivarot.h"
  22
  23
  24 Inkscape::ObjectSnapper::ObjectSnapper(SPNamedView const *nv, NR::Coord const d)
  25     : Snapper(nv, d), _snap_to_nodes(true), _snap_to_paths(true)
  26 {
  27
  28 }
  29
  30
  31 /**
  32  *  \param p Point we are trying to snap (desktop coordinates)
  33  */
  34
  35 void Inkscape::ObjectSnapper::_findCandidates(std::list<SPItem*>& c,
  36                                               SPObject* r,
  37                                               std::list<SPItem const *> const &it,
  38                                               NR::Point const &p) const
  39 {
  40     for (SPObject* o = r->children; o != NULL; o = o->next) {
  41         if (SP_IS_ITEM(o)) {
  42
  43             /* See if this item is on the ignore list */
  44             std::list<SPItem const *>::const_iterator i = it.begin();
  45             while (i != it.end() && *i != o) {
  46                 i++;
  47             }
  48
  49             if (i == it.end()) {
  50                 /* See if the item is within range */
  51                 NR::Rect const b = NR::expand(sp_item_bbox_desktop(SP_ITEM(o)), -getDistance());
  52                 if (b.contains(p)) {
  53                     c.push_back(SP_ITEM(o));
  54                 }
  55             }
  56         }
  57
  58         _findCandidates(c, o, it, p);
  59     }
  60 }
  61
  62
  63 void Inkscape::ObjectSnapper::_snapNodes(Inkscape::SnappedPoint &s,
  64                                          NR::Point const &p,
  65                                          std::list<SPItem*> const &cand) const
  66 {
  67     /* FIXME: this seems like a hack.  Perhaps Snappers should be
  68     ** in SPDesktop rather than SPNamedView?
  69     */
  70     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  71
  72     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
  73         if (SP_IS_SHAPE(*i)) {
  74
  75             SPShape const *sh = SP_SHAPE(*i);
  76             if (sh->curve) {
  77
  78                 int j = 0;
  79                 NR::Matrix const i2doc = sp_item_i2doc_affine(*i);
  80
  81                 while (sh->curve->bpath[j].code != NR_END) {
  82
  83                     /* Get this node in desktop coordinates */
  84                     NArtBpath const &bp = sh->curve->bpath[j];
  85                     NR::Point const n = desktop->doc2dt(bp.c(3) * i2doc);
  86
  87                     /* Try to snap to this node of the path */
  88                     NR::Coord const dist = NR::L2(n - p);
  89                     if (dist < getDistance() && dist < s.getDistance()) {
  90                         s = SnappedPoint(n, dist);
  91                     }
  92
  93                     j++;
  94                 }
  95             }
  96         }
  97     }
  98 }
  99
 100
 101 void Inkscape::ObjectSnapper::_snapPaths(Inkscape::SnappedPoint &s,
 102                                          NR::Point const &p,
 103                                          std::list<SPItem*> const &cand) const
 104 {
 105     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 106     ** in SPDesktop rather than SPNamedView?
 107     */
 108     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 109
 110     NR::Point const p_doc = desktop->dt2doc(p);
 111
 112     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
 113
 114         /* Transform the requested snap point to this item's coordinates */
 115         NR::Matrix const i2doc = sp_item_i2doc_affine(*i);
 116         NR::Point const p_it = p_doc * i2doc.inverse();
 117
 118         Path *livarot_path = Path_for_item(*i, true, true);
 119         if (!livarot_path)
 120             continue;
 121
 122         livarot_path->ConvertWithBackData(0.01);
 123
 124         /* Look for the nearest position on this SPItem to our snap point */
 125         NR::Maybe<Path::cut_position> const o = get_nearest_position_on_Path(livarot_path, p_it);
 126         if (o != NR::Nothing() && o.assume().t >= 0 && o.assume().t <= 1) {
 127
 128             /* Convert the nearest point back to desktop coordinates */
 129             NR::Point const o_it = get_point_on_Path(livarot_path, o.assume().piece, o.assume().t);
 130             NR::Point const o_dt = desktop->doc2dt(o_it * i2doc);
 131
 132             NR::Coord const dist = NR::L2(o_dt - p);
 133             if (dist < getDistance() && dist < s.getDistance()) {
 134                 s = SnappedPoint(o_dt, dist);
 135             }
 136         }
 137
 138         delete livarot_path;
 139     }
 140
 141 }
 142
 143
 144 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doFreeSnap(NR::Point const &p,
 145                                                             std::list<SPItem const *> const &it) const
 146 {
 147     if ( NULL == _named_view ) {
 148         return SnappedPoint(p, NR_HUGE);
 149     }
 150
 151     /* Get a list of all the SPItems that we will try to snap to */
 152     std::list<SPItem*> cand;
 153     _findCandidates(cand, sp_document_root(_named_view->document), it, p);
 154
 155     SnappedPoint s(p, NR_HUGE);
 156
 157     if (_snap_to_nodes) {
 158         _snapNodes(s, p, cand);
 159     }
 160     if (_snap_to_paths) {
 161         _snapPaths(s, p, cand);
 162     }
 163
 164     return s;
 165 }
 166
 167
 168
 169 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doConstrainedSnap(NR::Point const &p,
 170                                                                    ConstraintLine const &c,
 171                                                                    std::list<SPItem const *> const &it) const
 172 {
 173     /* FIXME: this needs implementing properly; I think we have to do the
 174     ** intersection of c with the objects.
 175     */
 176     return _doFreeSnap(p, it);
 177 }
 178
 179 /*
 180   Local Variables:
 181   mode:c++
 182   c-file-style:"stroustrup"
 183   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 184   indent-tabs-mode:nil
 185   fill-column:99
 186   End:
 187 */
 188 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :