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 TRANSLATE,
71 SCALE,
72 STRETCH,
73 SKEW,
74 ROTATE
75 };
77 SnapManager(SPNamedView const *v);
79 typedef std::list<const Inkscape::Snapper*> SnapperList;
81 bool someSnapperMightSnap() const;
82 bool gridSnapperMightSnap() const;
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);
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);
96 void setupIgnoreSelection(SPDesktop const *desktop,
97 bool snapindicator = true,
98 std::vector<Inkscape::SnapCandidatePoint> *unselected_nodes = NULL,
99 SPGuide *guide_to_ignore = NULL);
101 void unSetup() {_rotation_center_source_items = NULL;
102 _guide_to_ignore = NULL;
103 _desktop = NULL;
104 _unselected_nodes = NULL;}
106 // If we're dragging a rotation center, then setRotationCenterSource() stores the parent item
107 // of this rotation center; this reference is used to make sure that we do not snap a rotation
108 // center to itself
109 // NOTE: Must be called after calling setup(), not before!
110 void setRotationCenterSource(GSList *items) {_rotation_center_source_items = items;}
111 GSList const *getRotationCenterSource() {return _rotation_center_source_items;}
113 // freeSnapReturnByRef() is preferred over freeSnap(), because it only returns a
114 // point if snapping has occurred (by overwriting p); otherwise p is untouched
115 void freeSnapReturnByRef(Geom::Point &p,
116 Inkscape::SnapSourceType const source_type,
117 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
119 Inkscape::SnappedPoint freeSnap(Inkscape::SnapCandidatePoint const &p,
120 Geom::OptRect const &bbox_to_snap = Geom::OptRect() ) const;
122 void preSnap(Inkscape::SnapCandidatePoint const &p);
124 Geom::Point multipleOfGridPitch(Geom::Point const &t, Geom::Point const &origin);
126 // constrainedSnapReturnByRef() is preferred over constrainedSnap(), because it only returns a
127 // point, by overwriting p, if snapping has occurred; otherwise p is untouched
128 void constrainedSnapReturnByRef(Geom::Point &p,
129 Inkscape::SnapSourceType const source_type,
130 Inkscape::Snapper::SnapConstraint const &constraint,
131 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
133 Inkscape::SnappedPoint constrainedSnap(Inkscape::SnapCandidatePoint const &p,
134 Inkscape::Snapper::SnapConstraint const &constraint,
135 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
137 Inkscape::SnappedPoint multipleConstrainedSnaps(Inkscape::SnapCandidatePoint const &p,
138 std::vector<Inkscape::Snapper::SnapConstraint> const &constraints,
139 bool dont_snap = false,
140 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
142 Inkscape::SnappedPoint constrainedAngularSnap(Inkscape::SnapCandidatePoint const &p,
143 boost::optional<Geom::Point> const &p_ref,
144 Geom::Point const &o,
145 unsigned const snaps) const;
147 void guideFreeSnap(Geom::Point &p, Geom::Point const &guide_normal, SPGuideDragType drag_type) const;
148 void guideConstrainedSnap(Geom::Point &p, SPGuide const &guideline) const;
150 Inkscape::SnappedPoint freeSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
151 Geom::Point const &pointer,
152 Geom::Point const &tr) const;
154 Inkscape::SnappedPoint constrainedSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
155 Geom::Point const &pointer,
156 Inkscape::Snapper::SnapConstraint const &constraint,
157 Geom::Point const &tr) const;
159 Inkscape::SnappedPoint freeSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
160 Geom::Point const &pointer,
161 Geom::Scale const &s,
162 Geom::Point const &o) const;
164 Inkscape::SnappedPoint constrainedSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
165 Geom::Point const &pointer,
166 Geom::Scale const &s,
167 Geom::Point const &o) const;
169 Inkscape::SnappedPoint constrainedSnapStretch(std::vector<Inkscape::SnapCandidatePoint> const &p,
170 Geom::Point const &pointer,
171 Geom::Coord const &s,
172 Geom::Point const &o,
173 Geom::Dim2 d,
174 bool uniform) const;
176 Inkscape::SnappedPoint constrainedSnapSkew(std::vector<Inkscape::SnapCandidatePoint> const &p,
177 Geom::Point const &pointer,
178 Inkscape::Snapper::SnapConstraint const &constraint,
179 Geom::Point const &s, // s[0] = skew factor, s[1] = scale factor
180 Geom::Point const &o,
181 Geom::Dim2 d) const;
183 Inkscape::SnappedPoint constrainedSnapRotate(std::vector<Inkscape::SnapCandidatePoint> const &p,
184 Geom::Point const &pointer,
185 Geom::Coord const &angle,
186 Geom::Point const &o) const;
188 Inkscape::GuideSnapper guide; ///< guide snapper
189 Inkscape::ObjectSnapper object; ///< snapper to other objects
190 Inkscape::SnapPreferences snapprefs;
192 SnapperList getSnappers() const;
193 SnapperList getGridSnappers() const;
195 SPDesktop const *getDesktop() const {return _desktop;}
196 SPNamedView const *getNamedView() const {return _named_view;}
197 SPDocument *getDocument() const;
198 SPGuide const *getGuideToIgnore() const {return _guide_to_ignore;}
200 bool getSnapIndicator() const {return _snapindicator;}
202 Inkscape::SnappedPoint findBestSnap(Inkscape::SnapCandidatePoint const &p, SnappedConstraints const &sc, bool constrained, bool noCurves = false, bool allowOffScreen = false) const;
204 protected:
205 SPNamedView const *_named_view;
207 private:
208 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
209 GSList *_rotation_center_source_items; // to avoid snapping a rotation center to itself
210 SPGuide *_guide_to_ignore; ///< A guide that should not be snapped to, e.g. the guide that is currently being dragged
211 SPDesktop const *_desktop;
212 bool _snapindicator; ///< When true, an indicator will be drawn at the position that was being snapped to
213 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
215 Inkscape::SnappedPoint _snapTransformed(std::vector<Inkscape::SnapCandidatePoint> const &points,
216 Geom::Point const &pointer,
217 bool constrained,
218 Inkscape::Snapper::SnapConstraint const &constraint,
219 Transformation transformation_type,
220 Geom::Point const &transformation,
221 Geom::Point const &origin,
222 Geom::Dim2 dim,
223 bool uniform) const;
225 Geom::Point _transformPoint(Inkscape::SnapCandidatePoint const &p,
226 Transformation const transformation_type,
227 Geom::Point const &transformation,
228 Geom::Point const &origin,
229 Geom::Dim2 const dim,
230 bool const uniform) const;
232 void _displaySnapsource(Inkscape::SnapCandidatePoint const &p) const;
233 };
235 #endif /* !SEEN_SNAP_H */
237 /*
238 Local Variables:
239 mode:c++
240 c-file-style:"stroustrup"
241 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
242 indent-tabs-mode:nil
243 fill-column:99
244 End:
245 */
246 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :