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     void setupIgnoreSelection(SPDesktop const *desktop,
  96                               bool snapindicator = true,
  97                               std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
  98                               SPGuide *guide_to_ignore = NULL);
  99
 100     // freeSnapReturnByRef() is preferred over freeSnap(), because it only returns a
 101     // point if snapping has occurred (by overwriting p); otherwise p is untouched
 102     void freeSnapReturnByRef(Geom::Point &p,
 103                                 Inkscape::SnapSourceType const source_type,
 104                                 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 105
 106     Inkscape::SnappedPoint freeSnap(Inkscape::SnapCandidatePoint const &p,
 107                                     Geom::OptRect const &bbox_to_snap = Geom::OptRect() ) const;
 108
 109     void preSnap(Inkscape::SnapCandidatePoint const &p);
 110
 111     Geom::Point multipleOfGridPitch(Geom::Point const &t, Geom::Point const &origin);
 112
 113     // constrainedSnapReturnByRef() is preferred over constrainedSnap(), because it only returns a
 114     // point, by overwriting p, if snapping has occurred; otherwise p is untouched
 115     void constrainedSnapReturnByRef(Geom::Point &p,
 116                                     Inkscape::SnapSourceType const source_type,
 117                                     Inkscape::Snapper::SnapConstraint const &constraint,
 118                                     Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 119
 120     Inkscape::SnappedPoint constrainedSnap(Inkscape::SnapCandidatePoint const &p,
 121                                            Inkscape::Snapper::SnapConstraint const &constraint,
 122                                            Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
 123
 124     void guideFreeSnap(Geom::Point &p, Geom::Point const &guide_normal, SPGuideDragType drag_type) const;
 125     void guideConstrainedSnap(Geom::Point &p, SPGuide const &guideline) const;
 126
 127     Inkscape::SnappedPoint freeSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 128                                                Geom::Point const &pointer,
 129                                                Geom::Point const &tr) const;
 130
 131     Inkscape::SnappedPoint constrainedSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 132                                                       Geom::Point const &pointer,
 133                                                       Inkscape::Snapper::SnapConstraint const &constraint,
 134                                                       Geom::Point const &tr) const;
 135
 136     Inkscape::SnappedPoint freeSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
 137                                          Geom::Point const &pointer,
 138                                          Geom::Scale const &s,
 139                                          Geom::Point const &o) const;
 140
 141     Inkscape::SnappedPoint constrainedSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
 142                                                 Geom::Point const &pointer,
 143                                                 Geom::Scale const &s,
 144                                                 Geom::Point const &o) const;
 145
 146     Inkscape::SnappedPoint constrainedSnapStretch(std::vector<Inkscape::SnapCandidatePoint> const &p,
 147                                                   Geom::Point const &pointer,
 148                                                   Geom::Coord const &s,
 149                                                   Geom::Point const &o,
 150                                                   Geom::Dim2 d,
 151                                                   bool uniform) const;
 152
 153     Inkscape::SnappedPoint constrainedSnapSkew(std::vector<Inkscape::SnapCandidatePoint> const &p,
 154                                                Geom::Point const &pointer,
 155                                                Inkscape::Snapper::SnapConstraint const &constraint,
 156                                                Geom::Point const &s, // s[0] = skew factor, s[1] = scale factor
 157                                                Geom::Point const &o,
 158                                                Geom::Dim2 d) const;
 159
 160     Inkscape::SnappedPoint constrainedSnapRotate(std::vector<Inkscape::SnapCandidatePoint> const &p,
 161                                                     Geom::Point const &pointer,
 162                                                     Geom::Coord const &angle,
 163                                                     Geom::Point const &o) const;
 164
 165     Inkscape::GuideSnapper guide;      ///< guide snapper
 166     Inkscape::ObjectSnapper object;    ///< snapper to other objects
 167     Inkscape::SnapPreferences snapprefs;
 168
 169     SnapperList getSnappers() const;
 170     SnapperList getGridSnappers() const;
 171
 172     SPDesktop const *getDesktop() const {return _desktop;}
 173     SPNamedView const *getNamedView() const {return _named_view;}
 174     SPDocument *getDocument() const;
 175     SPGuide const *getGuideToIgnore() const {return _guide_to_ignore;}
 176
 177     bool getSnapIndicator() const {return _snapindicator;}
 178
 179     Inkscape::SnappedPoint findBestSnap(Inkscape::SnapCandidatePoint const &p, SnappedConstraints const &sc, bool constrained, bool noCurves = false, bool allowOffScreen = false) const;
 180
 181 protected:
 182     SPNamedView const *_named_view;
 183
 184 private:
 185     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
 186     SPGuide *_guide_to_ignore; ///< A guide that should not be snapped to, e.g. the guide that is currently being dragged
 187     SPDesktop const *_desktop;
 188     bool _snapindicator; ///< When true, an indicator will be drawn at the position that was being snapped to
 189     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
 190
 191     Inkscape::SnappedPoint _snapTransformed(std::vector<Inkscape::SnapCandidatePoint> const &points,
 192                                             Geom::Point const &pointer,
 193                                             bool constrained,
 194                                             Inkscape::Snapper::SnapConstraint const &constraint,
 195                                             Transformation transformation_type,
 196                                             Geom::Point const &transformation,
 197                                             Geom::Point const &origin,
 198                                             Geom::Dim2 dim,
 199                                             bool uniform) const;
 200
 201     Geom::Point _transformPoint(Inkscape::SnapCandidatePoint const &p,
 202                                             Transformation const transformation_type,
 203                                             Geom::Point const &transformation,
 204                                             Geom::Point const &origin,
 205                                             Geom::Dim2 const dim,
 206                                             bool const uniform) const;
 207
 208     void _displaySnapsource(Inkscape::SnapCandidatePoint const &p) const;
 209 };
 210
 211 #endif /* !SEEN_SNAP_H */
 212
 213 /*
 214   Local Variables:
 215   mode:c++
 216   c-file-style:"stroustrup"
 217   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 218   indent-tabs-mode:nil
 219   fill-column:99
 220   End:
 221 */
 222 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :