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
  27
  28 Inkscape::ObjectSnapper::ObjectSnapper(SPNamedView const *nv, NR::Coord const d)
  29     : Snapper(nv, d), _snap_to_nodes(true), _snap_to_paths(true)
  30 {
  31
  32 }
  33
  34
  35 /**
  36  *  \param p Point we are trying to snap (desktop coordinates)
  37  */
  38
  39 void Inkscape::ObjectSnapper::_findCandidates(std::list<SPItem*>& c,
  40                                               SPObject* r,
  41                                               std::list<SPItem const *> const &it,
  42                                               NR::Point const &p) const
  43 {
  44     if (ThisSnapperMightSnap()) {
  45         SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  46         for (SPObject* o = sp_object_first_child(r); o != NULL; o = SP_OBJECT_NEXT(o)) {
  47             if (SP_IS_ITEM(o) && !SP_ITEM(o)->isLocked() && !desktop->itemIsHidden(SP_ITEM(o))) {
  48
  49                 /* See if this item is on the ignore list */
  50                 std::list<SPItem const *>::const_iterator i = it.begin();
  51                 while (i != it.end() && *i != o) {
  52                     i++;
  53                 }
  54
  55                 if (i == it.end()) {
  56                     /* See if the item is within range */
  57                     if (SP_IS_GROUP(o)) {
  58                         _findCandidates(c, o, it, p);
  59                     } else {
  60                         NR::Maybe<NR::Rect> b = sp_item_bbox_desktop(SP_ITEM(o));
  61                         if ( b && NR::expand(*b, -getDistance()).contains(p) ) {
  62                             c.push_back(SP_ITEM(o));
  63                         }
  64                     }
  65                 }
  66
  67             }
  68         }
  69     }
  70 }
  71
  72
  73 void Inkscape::ObjectSnapper::_snapNodes(Inkscape::SnappedPoint &s,
  74                                          NR::Point const &p,
  75                                          std::list<SPItem*> const &cand) const
  76 {
  77     /* FIXME: this seems like a hack.  Perhaps Snappers should be
  78     ** in SPDesktop rather than SPNamedView?
  79     */
  80     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
  81
  82     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
  83
  84         NR::Matrix i2doc(NR::identity());
  85         SPItem *root_item = NULL;
  86         if (SP_IS_USE(*i)) {
  87             i2doc = sp_use_get_root_transform(SP_USE(*i));
  88             root_item = sp_use_root(SP_USE(*i));
  89         } else {
  90             i2doc = sp_item_i2doc_affine(*i);
  91             root_item = *i;
  92         }
  93
  94         SPCurve *curve = NULL;
  95
  96         if (SP_IS_SHAPE(root_item)) {
  97             SPShape const *sh = SP_SHAPE(root_item);
  98             curve = sh->curve;
  99         } else if (SP_IS_IMAGE(root_item)) {
 100             SPImage const *im = SP_IMAGE(root_item);
 101             curve = im->curve;
 102         }
 103
 104         if (curve) {
 105
 106             int j = 0;
 107
 108             while (SP_CURVE_BPATH(curve)[j].code != NR_END) {
 109
 110                 /* Get this node in desktop coordinates */
 111                 NArtBpath const &bp = SP_CURVE_BPATH(curve)[j];
 112                 NR::Point const n = desktop->doc2dt(bp.c(3) * i2doc);
 113
 114                 /* Try to snap to this node of the path */
 115                 NR::Coord const dist = NR::L2(n - p);
 116                 if (dist < getDistance() && dist < s.getDistance()) {
 117                     s = SnappedPoint(n, dist);
 118                 }
 119
 120                 j++;
 121             }
 122         }
 123     }
 124 }
 125
 126
 127 void Inkscape::ObjectSnapper::_snapPaths(Inkscape::SnappedPoint &s,
 128                                          NR::Point const &p,
 129                                          std::list<SPItem*> const &cand) const
 130 {
 131     /* FIXME: this seems like a hack.  Perhaps Snappers should be
 132     ** in SPDesktop rather than SPNamedView?
 133     */
 134     SPDesktop const *desktop = SP_ACTIVE_DESKTOP;
 135
 136     NR::Point const p_doc = desktop->dt2doc(p);
 137
 138     for (std::list<SPItem*>::const_iterator i = cand.begin(); i != cand.end(); i++) {
 139
 140         /* Transform the requested snap point to this item's coordinates */
 141         NR::Matrix i2doc(NR::identity());
 142         SPItem *root_item = NULL;
 143         /* We might have a clone at hand, so make sure we get the root item */
 144         if (SP_IS_USE(*i)) {
 145             i2doc = sp_use_get_root_transform(SP_USE(*i));
 146             root_item = sp_use_root(SP_USE(*i));
 147         } else {
 148             i2doc = sp_item_i2doc_affine(*i);
 149             root_item = *i;
 150         }
 151
 152         NR::Point const p_it = p_doc * i2doc.inverse();
 153
 154         Path *livarot_path = Path_for_item(root_item, false, false);
 155         if (!livarot_path)
 156             continue;
 157
 158         livarot_path->ConvertWithBackData(0.01);
 159
 160         /* Look for the nearest position on this SPItem to our snap point */
 161         NR::Maybe<Path::cut_position> const o = get_nearest_position_on_Path(livarot_path, p_it);
 162         if (o && o->t >= 0 && o->t <= 1) {
 163
 164             /* Convert the nearest point back to desktop coordinates */
 165             NR::Point const o_it = get_point_on_Path(livarot_path, o->piece, o->t);
 166             NR::Point const o_dt = desktop->doc2dt(o_it * i2doc);
 167
 168             NR::Coord const dist = NR::L2(o_dt - p);
 169             if (dist < getDistance() && dist < s.getDistance()) {
 170                 s = SnappedPoint(o_dt, dist);
 171             }
 172         }
 173
 174         delete livarot_path;
 175     }
 176 }
 177
 178
 179 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doFreeSnap(NR::Point const &p,
 180                                                             std::list<SPItem const *> const &it) const
 181 {
 182     if ( NULL == _named_view ) {
 183         return SnappedPoint(p, NR_HUGE);
 184     }
 185
 186     /* Get a list of all the SPItems that we will try to snap to */
 187     std::list<SPItem*> cand;
 188     _findCandidates(cand, sp_document_root(_named_view->document), it, p);
 189
 190     SnappedPoint s(p, NR_HUGE);
 191
 192     if (_snap_to_nodes) {
 193         _snapNodes(s, p, cand);
 194     }
 195     if (_snap_to_paths) {
 196         _snapPaths(s, p, cand);
 197     }
 198
 199     return s;
 200 }
 201
 202
 203
 204 Inkscape::SnappedPoint Inkscape::ObjectSnapper::_doConstrainedSnap(NR::Point const &p,
 205                                                                    ConstraintLine const &c,
 206                                                                    std::list<SPItem const *> const &it) const
 207 {
 208     /* FIXME: this needs implementing properly; I think we have to do the
 209     ** intersection of c with the objects.
 210     */
 211     return _doFreeSnap(p, it);
 212 }
 213
 214 /**
 215  *  \return true if this Snapper will snap at least one kind of point.
 216  */
 217 bool Inkscape::ObjectSnapper::ThisSnapperMightSnap() const
 218 {
 219     return (_enabled && _snap_to != 0 && (_snap_to_paths || _snap_to_nodes));
 220 }
 221
 222
 223 /*
 224   Local Variables:
 225   mode:c++
 226   c-file-style:"stroustrup"
 227   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 228   indent-tabs-mode:nil
 229   fill-column:99
 230   End:
 231 */
 232 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :