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 // If we're dragging a rotation center, then setRotationCenterSource() stores the parent item
102 // of this rotation center; this reference is used to make sure that we do not snap a rotation
103 // center to itself
104 // NOTE: Must be called after calling setup(), not before!
105 void setRotationCenterSource(SPItem *item) {_rotation_center_source_item = item;}
106 SPItem* getRotationCenterSource() {return _rotation_center_source_item;}
108 // freeSnapReturnByRef() is preferred over freeSnap(), because it only returns a
109 // point if snapping has occurred (by overwriting p); otherwise p is untouched
110 void freeSnapReturnByRef(Geom::Point &p,
111 Inkscape::SnapSourceType const source_type,
112 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
114 Inkscape::SnappedPoint freeSnap(Inkscape::SnapCandidatePoint const &p,
115 Geom::OptRect const &bbox_to_snap = Geom::OptRect() ) const;
117 void preSnap(Inkscape::SnapCandidatePoint const &p);
119 Geom::Point multipleOfGridPitch(Geom::Point const &t, Geom::Point const &origin);
121 // constrainedSnapReturnByRef() is preferred over constrainedSnap(), because it only returns a
122 // point, by overwriting p, if snapping has occurred; otherwise p is untouched
123 void constrainedSnapReturnByRef(Geom::Point &p,
124 Inkscape::SnapSourceType const source_type,
125 Inkscape::Snapper::SnapConstraint const &constraint,
126 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
128 Inkscape::SnappedPoint constrainedSnap(Inkscape::SnapCandidatePoint const &p,
129 Inkscape::Snapper::SnapConstraint const &constraint,
130 Geom::OptRect const &bbox_to_snap = Geom::OptRect()) const;
132 void guideFreeSnap(Geom::Point &p, Geom::Point const &guide_normal, SPGuideDragType drag_type) const;
133 void guideConstrainedSnap(Geom::Point &p, SPGuide const &guideline) const;
135 Inkscape::SnappedPoint freeSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
136 Geom::Point const &pointer,
137 Geom::Point const &tr) const;
139 Inkscape::SnappedPoint constrainedSnapTranslate(std::vector<Inkscape::SnapCandidatePoint> const &p,
140 Geom::Point const &pointer,
141 Inkscape::Snapper::SnapConstraint const &constraint,
142 Geom::Point const &tr) const;
144 Inkscape::SnappedPoint freeSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
145 Geom::Point const &pointer,
146 Geom::Scale const &s,
147 Geom::Point const &o) const;
149 Inkscape::SnappedPoint constrainedSnapScale(std::vector<Inkscape::SnapCandidatePoint> const &p,
150 Geom::Point const &pointer,
151 Geom::Scale const &s,
152 Geom::Point const &o) const;
154 Inkscape::SnappedPoint constrainedSnapStretch(std::vector<Inkscape::SnapCandidatePoint> const &p,
155 Geom::Point const &pointer,
156 Geom::Coord const &s,
157 Geom::Point const &o,
158 Geom::Dim2 d,
159 bool uniform) const;
161 Inkscape::SnappedPoint constrainedSnapSkew(std::vector<Inkscape::SnapCandidatePoint> const &p,
162 Geom::Point const &pointer,
163 Inkscape::Snapper::SnapConstraint const &constraint,
164 Geom::Point const &s, // s[0] = skew factor, s[1] = scale factor
165 Geom::Point const &o,
166 Geom::Dim2 d) const;
168 Inkscape::SnappedPoint constrainedSnapRotate(std::vector<Inkscape::SnapCandidatePoint> const &p,
169 Geom::Point const &pointer,
170 Geom::Coord const &angle,
171 Geom::Point const &o) const;
173 Inkscape::GuideSnapper guide; ///< guide snapper
174 Inkscape::ObjectSnapper object; ///< snapper to other objects
175 Inkscape::SnapPreferences snapprefs;
177 SnapperList getSnappers() const;
178 SnapperList getGridSnappers() const;
180 SPDesktop const *getDesktop() const {return _desktop;}
181 SPNamedView const *getNamedView() const {return _named_view;}
182 SPDocument *getDocument() const;
183 SPGuide const *getGuideToIgnore() const {return _guide_to_ignore;}
185 bool getSnapIndicator() const {return _snapindicator;}
187 Inkscape::SnappedPoint findBestSnap(Inkscape::SnapCandidatePoint const &p, SnappedConstraints const &sc, bool constrained, bool noCurves = false, bool allowOffScreen = false) const;
189 protected:
190 SPNamedView const *_named_view;
192 private:
193 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
194 SPItem *_rotation_center_source_item; // to avoid snapping a rotation center to itself
195 SPGuide *_guide_to_ignore; ///< A guide that should not be snapped to, e.g. the guide that is currently being dragged
196 SPDesktop const *_desktop;
197 bool _snapindicator; ///< When true, an indicator will be drawn at the position that was being snapped to
198 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
200 Inkscape::SnappedPoint _snapTransformed(std::vector<Inkscape::SnapCandidatePoint> const &points,
201 Geom::Point const &pointer,
202 bool constrained,
203 Inkscape::Snapper::SnapConstraint const &constraint,
204 Transformation transformation_type,
205 Geom::Point const &transformation,
206 Geom::Point const &origin,
207 Geom::Dim2 dim,
208 bool uniform) const;
210 Geom::Point _transformPoint(Inkscape::SnapCandidatePoint const &p,
211 Transformation const transformation_type,
212 Geom::Point const &transformation,
213 Geom::Point const &origin,
214 Geom::Dim2 const dim,
215 bool const uniform) const;
217 void _displaySnapsource(Inkscape::SnapCandidatePoint const &p) const;
218 };
220 #endif /* !SEEN_SNAP_H */
222 /*
223 Local Variables:
224 mode:c++
225 c-file-style:"stroustrup"
226 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
227 indent-tabs-mode:nil
228 fill-column:99
229 End:
230 */
231 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :