src/snap.h

   1 /**
   2  * \file snap.h
   3  * \brief Per-desktop object that handles snapping queries
   4  *//*
   5  * Authors:
   6  *   Lauris Kaplinski <lauris@kaplinski.com>
   7  *   Frank Felfe <innerspace@iname.com>
   8  *   Carl Hetherington <inkscape@carlh.net>
   9  *   Diederik van Lierop <mail@diedenrezi.nl>
  10  *
  11  * Copyright (C) 2006-2007 Johan Engelen <johan@shouraizou.nl>
  12  * Copyright (C) 2000-2002 Lauris Kaplinski
  13  * Copyright (C) 2000-2010 Authors
  14  *
  15  * Released under GNU GPL, read the file 'COPYING' for more information
  16  */
  17
  18 #ifndef SEEN_SNAP_H
  19 #define SEEN_SNAP_H
  20
  21 #include <vector>
  22 #include "guide-snapper.h"
  23 #include "object-snapper.h"
  24 #include "snap-preferences.h"
  25
  26 /* Guides */
  27 enum SPGuideDragType { // used both here and in desktop-events.cpp
  28     SP_DRAG_TRANSLATE,
  29     SP_DRAG_ROTATE,
  30     SP_DRAG_MOVE_ORIGIN,
  31     SP_DRAG_NONE
  32 };
  33
  34 class SPNamedView;
  35
  36 /// Class to coordinate snapping operations
  37 /**
  38  * The SnapManager class handles most (if not all) of the interfacing of the snapping mechanisms
  39  * with the other parts of the code base. It stores the references to the various types of snappers
  40  * for grid, guides and objects, and it stores most of the snapping preferences. Besides that
  41  * it provides methods to setup the snapping environment (e.g. keeps a list of the items to ignore
  42  * when looking for snap target candidates, and toggling of the snap indicator), and it provides
  43  * many different methods for snapping queries (free snapping vs. constrained snapping,
  44  * returning the result by reference or through a return statement, etc.)
  45  *
  46  * Each SPNamedView has one of these.  It offers methods to snap points to whatever
  47  * snappers are defined (e.g. grid, guides etc.).  It also allows callers to snap
  48  * points which have undergone some transformation (e.g. translation, scaling etc.)
  49  *
  50  * \par How snapping is implemented in Inkscape
  51  * \par
  52  * The snapping system consists of two key elements. The first one is the snap manager
  53  * (this class), which keeps some data about objects in the document and answers queries
  54  * of the type "given this point and type of transformation, what is the best place
  55  * to snap to?".
  56  *
  57  * The second is in event-context.cpp and implements the snapping timeout. Whenever a motion
  58  * events happens over the canvas, it stores it for later use and initiates a timeout.
  59  * This timeout is discarded whenever a new motion event occurs. When the timeout expires,
  60  * a global flag in SnapManager, accessed via getSnapPostponedGlobally(), is set to true
  61  * and the stored event is replayed, but this time with snapping enabled. This way you can
  62  * write snapping code directly in your control point's dragged handler as if there was
  63  * no timeout.
  64  */
  65
  66 class SnapManager
  67 {
  68 public:
  69     enum Transformation {
  70         TRANSLATE,
  71         SCALE,
  72         STRETCH,
  73         SKEW,
  74         ROTATE
  75     };
  76
  77     SnapManager(SPNamedView const *v);
  78
  79     typedef std::list<const Inkscape::Snapper*> SnapperList;
  80
  81     bool someSnapperMightSnap() const;
  82     bool gridSnapperMightSnap() const;
  83
  84     void setup(SPDesktop const *desktop,
  85             bool snapindicator = true,
  86             SPItem const *item_to_ignore = NULL,
  87             std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  88             SPGuide *guide_to_ignore = NULL);
  89
  90     void setup(SPDesktop const *desktop,
  91                bool snapindicator,
  92                std::vector<SPItem const *> &items_to_ignore,
  93                std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  94                SPGuide *guide_to_ignore = NULL);
  95
  96     void setupIgnoreSelection(SPDesktop const *desktop,
  97                               bool snapindicator = true,
  98                               std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  99                               SPGuide *guide_to_ignore = NULL);
 100
 101     void unSetup() {_rotation_center_source_item = NULL;
 102                     _guide_to_ignore = NULL;
 103                     _desktop = NULL;
 104                     _named_view = NULL;
 105                     _unselected_nodes = NULL;}
 106
 107     // If we're dragging a rotation center, then setRotationCenterSource() stores the parent item
 108     // of this rotation center; this reference is used to make sure that we do not snap a rotation
 109     // center to itself
 110     // NOTE: Must be called after calling setup(), not before!
 111     void setRotationCenterSource(SPItem *item) {_rotation_center_source_item = item;}
 112     SPItem* getRotationCenterSource() {return _rotation_center_source_item;}
 113
 114     // freeSnapReturnByRef() is preferred over freeSnap(), because it only returns a
 115     // point if snapping has occurred (by overwriting p); otherwise p is untouched
 116     void freeSnapReturnByRef(Geom::Point &p,
 117                                 Inkscape::SnapSourceType const source_type,
 118                                 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 119
 120     Inkscape::SnappedPoint freeSnap(Inkscape::SnapCandidatePoint const &p,
 121                                     Geom::OptRect const &bbox_to_snap = Geom::OptRect() ) const;
 122
 123     void preSnap(Inkscape::SnapCandidatePoint const &p);
 124
 125     Geom::Point multipleOfGridPitch(Geom::Point const &t, Geom::Point const &origin);
 126
 127     // constrainedSnapReturnByRef() is preferred over constrainedSnap(), because it only returns a
 128     // point, by overwriting p, if snapping has occurred; otherwise p is untouched
 129     void constrainedSnapReturnByRef(Geom::Point &p,
 130                                     Inkscape::SnapSourceType const source_type,
 131                                     Inkscape::Snapper::SnapConstraint const &constraint,
 132                                     Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 133
 134     Inkscape::SnappedPoint constrainedSnap(Inkscape::SnapCandidatePoint const &p,
 135                                            Inkscape::Snapper::SnapConstraint const &constraint,
 136                                            Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 137
 138     Inkscape::SnappedPoint multipleConstrainedSnaps(Inkscape::SnapCandidatePoint const &p,
 139                                                         std::vector<Inkscape::Snapper::SnapConstraint> const &constraints,
 140                                                         Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 141
 142     void guideFreeSnap(Geom::Point &p, Geom::Point const &guide_normal, SPGuideDragType drag_type) const;
 143     void guideConstrainedSnap(Geom::Point &p, SPGuide const &guideline) const;
 144
 145     Inkscape::SnappedPoint freeSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 146                                                Geom::Point const &pointer,
 147                                                Geom::Point const &tr) const;
 148
 149     Inkscape::SnappedPoint constrainedSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 150                                                       Geom::Point const &pointer,
 151                                                       Inkscape::Snapper::SnapConstraint const &constraint,
 152                                                       Geom::Point const &tr) const;
 153
 154     Inkscape::SnappedPoint freeSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
 155                                          Geom::Point const &pointer,
 156                                          Geom::Scale const &s,
 157                                          Geom::Point const &o) const;
 158
 159     Inkscape::SnappedPoint constrainedSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
 160                                                 Geom::Point const &pointer,
 161                                                 Geom::Scale const &s,
 162                                                 Geom::Point const &o) const;
 163
 164     Inkscape::SnappedPoint constrainedSnapStretch(std::vector<Inkscape::SnapCandidatePoint> const &p,
 165                                                   Geom::Point const &pointer,
 166                                                   Geom::Coord const &s,
 167                                                   Geom::Point const &o,
 168                                                   Geom::Dim2 d,
 169                                                   bool uniform) const;
 170
 171     Inkscape::SnappedPoint constrainedSnapSkew(std::vector<Inkscape::SnapCandidatePoint> const &p,
 172                                                Geom::Point const &pointer,
 173                                                Inkscape::Snapper::SnapConstraint const &constraint,
 174                                                Geom::Point const &s, // s[0] = skew factor, s[1] = scale factor
 175                                                Geom::Point const &o,
 176                                                Geom::Dim2 d) const;
 177
 178     Inkscape::SnappedPoint constrainedSnapRotate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 179                                                     Geom::Point const &pointer,
 180                                                     Geom::Coord const &angle,
 181                                                     Geom::Point const &o) const;
 182
 183     Inkscape::GuideSnapper guide;      ///< guide snapper
 184     Inkscape::ObjectSnapper object;    ///< snapper to other objects
 185     Inkscape::SnapPreferences snapprefs;
 186
 187     SnapperList getSnappers() const;
 188     SnapperList getGridSnappers() const;
 189
 190     SPDesktop const *getDesktop() const {return _desktop;}
 191     SPNamedView const *getNamedView() const {return _named_view;}
 192     SPDocument *getDocument() const;
 193     SPGuide const *getGuideToIgnore() const {return _guide_to_ignore;}
 194
 195     bool getSnapIndicator() const {return _snapindicator;}
 196
 197     Inkscape::SnappedPoint findBestSnap(Inkscape::SnapCandidatePoint const &p, SnappedConstraints const &sc, bool constrained, bool noCurves = false, bool allowOffScreen = false) const;
 198
 199 protected:
 200     SPNamedView const *_named_view;
 201
 202 private:
 203     std::vector<SPItem const *> _items_to_ignore; ///< Items that should not be snapped to, for example the items that are currently being dragged. Set using the setup() method
 204     SPItem *_rotation_center_source_item; // to avoid snapping a rotation center to itself
 205     SPGuide *_guide_to_ignore; ///< A guide that should not be snapped to, e.g. the guide that is currently being dragged
 206     SPDesktop const *_desktop;
 207     bool _snapindicator; ///< When true, an indicator will be drawn at the position that was being snapped to
 208     std::vector<Inkscape::SnapCandidatePoint> *_unselected_nodes; ///< Nodes of the path that is currently being edited and which have not been selected and which will therefore be stationary. Only these nodes will be considered for snapping to. Of each unselected node both the position (Geom::Point) and the type (Inkscape::SnapTargetType) will be stored
 209
 210     Inkscape::SnappedPoint _snapTransformed(std::vector<Inkscape::SnapCandidatePoint> const &points,
 211                                             Geom::Point const &pointer,
 212                                             bool constrained,
 213                                             Inkscape::Snapper::SnapConstraint const &constraint,
 214                                             Transformation transformation_type,
 215                                             Geom::Point const &transformation,
 216                                             Geom::Point const &origin,
 217                                             Geom::Dim2 dim,
 218                                             bool uniform) const;
 219
 220     Geom::Point _transformPoint(Inkscape::SnapCandidatePoint const &p,
 221                                             Transformation const transformation_type,
 222                                             Geom::Point const &transformation,
 223                                             Geom::Point const &origin,
 224                                             Geom::Dim2 const dim,
 225                                             bool const uniform) const;
 226
 227     void _displaySnapsource(Inkscape::SnapCandidatePoint const &p) const;
 228 };
 229
 230 #endif /* !SEEN_SNAP_H */
 231
 232 /*
 233   Local Variables:
 234   mode:c++
 235   c-file-style:"stroustrup"
 236   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 237   indent-tabs-mode:nil
 238   fill-column:99
 239   End:
 240 */
 241 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :