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 */
18 #ifndef SEEN_SNAP_H
19 #define SEEN_SNAP_H
21 #include <vector>
22 #include "guide-snapper.h"
23 #include "object-snapper.h"
24 #include "snap-preferences.h"
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 };
34 class SPNamedView;
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 */
66 class SnapManager
67 {
68 public:
69 enum Transformation {
70 TRANSLATION,
71 SCALE,
72 STRETCH,
73 SKEW
74 };
76 SnapManager(SPNamedView const *v);
78 typedef std::list<const Inkscape::Snapper*> SnapperList;
80 bool someSnapperMightSnap() const;
81 bool gridSnapperMightSnap() const;
83 void setup(SPDesktop const *desktop,
84 bool snapindicator = true,
85 SPItem const *item_to_ignore = NULL,
86 std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
87 SPGuide *guide_to_ignore = NULL);
89 void setup(SPDesktop const *desktop,
90 bool snapindicator,
91 std::vector<SPItem const *> &items_to_ignore,
92 std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
93 SPGuide *guide_to_ignore = NULL);
94 void setupIgnoreSelection(SPDesktop const *desktop,
95 bool snapindicator = true,
96 std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
97 SPGuide *guide_to_ignore = NULL);
99 // freeSnapReturnByRef() is preferred over freeSnap(), because it only returns a
100 // point if snapping has occurred (by overwriting p); otherwise p is untouched
101 void freeSnapReturnByRef(Geom::Point &p,
102 Inkscape::SnapSourceType const source_type,
103 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
105 Inkscape::SnappedPoint freeSnap(Inkscape::SnapCandidatePoint const &p,
106 Geom::OptRect const &bbox_to_snap = Geom::OptRect() ) const;
108 void preSnap(Inkscape::SnapCandidatePoint const &p);
110 Geom::Point multipleOfGridPitch(Geom::Point const &t, Geom::Point const &origin);
112 // constrainedSnapReturnByRef() is preferred over constrainedSnap(), because it only returns a
113 // point, by overwriting p, if snapping has occurred; otherwise p is untouched
114 void constrainedSnapReturnByRef(Geom::Point &p,
115 Inkscape::SnapSourceType const source_type,
116 Inkscape::Snapper::ConstraintLine const &constraint,
117 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
119 Inkscape::SnappedPoint constrainedSnap(Inkscape::SnapCandidatePoint const &p,
120 Inkscape::Snapper::ConstraintLine const &constraint,
121 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
123 void guideFreeSnap(Geom::Point &p, Geom::Point const &guide_normal, SPGuideDragType drag_type) const;
124 void guideConstrainedSnap(Geom::Point &p, SPGuide const &guideline) const;
126 Inkscape::SnappedPoint freeSnapTranslation(std::vector<Inkscape::SnapCandidatePoint> const &p,
127 Geom::Point const &pointer,
128 Geom::Point const &tr) const;
130 Inkscape::SnappedPoint constrainedSnapTranslation(std::vector<Inkscape::SnapCandidatePoint> const &p,
131 Geom::Point const &pointer,
132 Inkscape::Snapper::ConstraintLine const &constraint,
133 Geom::Point const &tr) const;
135 Inkscape::SnappedPoint freeSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
136 Geom::Point const &pointer,
137 Geom::Scale const &s,
138 Geom::Point const &o) const;
140 Inkscape::SnappedPoint constrainedSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
141 Geom::Point const &pointer,
142 Geom::Scale const &s,
143 Geom::Point const &o) const;
145 Inkscape::SnappedPoint constrainedSnapStretch(std::vector<Inkscape::SnapCandidatePoint> const &p,
146 Geom::Point const &pointer,
147 Geom::Coord const &s,
148 Geom::Point const &o,
149 Geom::Dim2 d,
150 bool uniform) const;
152 Inkscape::SnappedPoint constrainedSnapSkew(std::vector<Inkscape::SnapCandidatePoint> const &p,
153 Geom::Point const &pointer,
154 Inkscape::Snapper::ConstraintLine const &constraint,
155 Geom::Point const &s, // s[0] = skew factor, s[1] = scale factor
156 Geom::Point const &o,
157 Geom::Dim2 d) const;
159 Inkscape::GuideSnapper guide; ///< guide snapper
160 Inkscape::ObjectSnapper object; ///< snapper to other objects
161 Inkscape::SnapPreferences snapprefs;
163 SnapperList getSnappers() const;
164 SnapperList getGridSnappers() const;
166 SPDesktop const *getDesktop() const {return _desktop;}
167 SPNamedView const *getNamedView() const {return _named_view;}
168 SPDocument *getDocument() const;
169 SPGuide const *getGuideToIgnore() const {return _guide_to_ignore;}
171 bool getSnapIndicator() const {return _snapindicator;}
173 Inkscape::SnappedPoint findBestSnap(Inkscape::SnapCandidatePoint const &p, SnappedConstraints const &sc, bool constrained, bool noCurves = false, bool allowOffScreen = false) const;
175 protected:
176 SPNamedView const *_named_view;
178 private:
179 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
180 SPGuide *_guide_to_ignore; ///< A guide that should not be snapped to, e.g. the guide that is currently being dragged
181 SPDesktop const *_desktop;
182 bool _snapindicator; ///< When true, an indicator will be drawn at the position that was being snapped to
183 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
184 //TODO: Make _unselected_nodes type safe; in the line above int is used for Inkscape::SnapTargetType, but if I remember
185 //correctly then in other cases the int is being used for Inkscape::SnapSourceType, or for both. How to make
186 //this type safe?
188 Inkscape::SnappedPoint _snapTransformed(std::vector<Inkscape::SnapCandidatePoint> const &points,
189 Geom::Point const &pointer,
190 bool constrained,
191 Inkscape::Snapper::ConstraintLine const &constraint,
192 Transformation transformation_type,
193 Geom::Point const &transformation,
194 Geom::Point const &origin,
195 Geom::Dim2 dim,
196 bool uniform) const;
198 Geom::Point _transformPoint(Inkscape::SnapCandidatePoint const &p,
199 Transformation const transformation_type,
200 Geom::Point const &transformation,
201 Geom::Point const &origin,
202 Geom::Dim2 const dim,
203 bool const uniform) const;
205 void _displaySnapsource(Inkscape::SnapCandidatePoint const &p) const;
206 };
208 #endif /* !SEEN_SNAP_H */
210 /*
211 Local Variables:
212 mode:c++
213 c-file-style:"stroustrup"
214 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
215 indent-tabs-mode:nil
216 fill-column:99
217 End:
218 */
219 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :