c37f34ce7a73dd2beb7d03d131fabda110d42d95
1 #define INKSCAPE_LPE_BENDPATH_CPP
3 /*
4 * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
5 * Copyright (C) Steren Giannini 2008 <steren.giannini@gmail.com>
6 *
7 * Released under GNU GPL, read the file 'COPYING' for more information
8 */
10 #include "live_effects/lpe-bendpath.h"
11 #include "sp-shape.h"
12 #include "sp-item.h"
13 #include "sp-path.h"
14 #include "sp-item-group.h"
15 #include "display/curve.h"
16 #include <libnr/n-art-bpath.h>
17 #include <libnr/nr-matrix-fns.h>
18 #include "libnr/n-art-bpath-2geom.h"
19 #include "svg/svg.h"
20 #include "ui/widget/scalar.h"
22 #include <2geom/sbasis.h>
23 #include <2geom/sbasis-geometric.h>
24 #include <2geom/bezier-to-sbasis.h>
25 #include <2geom/sbasis-to-bezier.h>
26 #include <2geom/d2.h>
27 #include <2geom/piecewise.h>
29 #include <algorithm>
30 using std::vector;
33 /* Theory in e-mail from J.F. Barraud
34 Let B be the skeleton path, and P the pattern (the path to be deformed).
36 P is a map t --> P(t) = ( x(t), y(t) ).
37 B is a map t --> B(t) = ( a(t), b(t) ).
39 The first step is to re-parametrize B by its arc length: this is the parametrization in which a point p on B is located by its distance s from start. One obtains a new map s --> U(s) = (a'(s),b'(s)), that still describes the same path B, but where the distance along B from start to
40 U(s) is s itself.
42 We also need a unit normal to the path. This can be obtained by computing a unit tangent vector, and rotate it by 90°. Call this normal vector N(s).
44 The basic deformation associated to B is then given by:
46 (x,y) --> U(x)+y*N(x)
48 (i.e. we go for distance x along the path, and then for distance y along the normal)
50 Of course this formula needs some minor adaptations (as is it depends on the absolute position of P for instance, so a little translation is needed
51 first) but I think we can first forget about them.
52 */
54 namespace Inkscape {
55 namespace LivePathEffect {
57 LPEBendPath::LPEBendPath(LivePathEffectObject *lpeobject) :
58 Effect(lpeobject),
59 bend_path(_("Bend path"), _("Path along which to bend the original path"), "bendpath", &wr, this, "M0,0 L1,0"),
60 prop_scale(_("Width"), _("Width of the path"), "prop_scale", &wr, this, 1),
61 scale_y_rel(_("Width in units of length"), _("Scale the width of the path in units of its length"), "scale_y_rel", &wr, this, false),
62 vertical_pattern(_("Original path is vertical"), _("Rotates the original 90 degrees, before bending it along the bend path"), "vertical", &wr, this, false)
63 {
64 registerParameter( dynamic_cast<Parameter *>(&bend_path) );
65 registerParameter( dynamic_cast<Parameter *>(&prop_scale) );
66 registerParameter( dynamic_cast<Parameter *>(&scale_y_rel) );
67 registerParameter( dynamic_cast<Parameter *>(&vertical_pattern) );
69 prop_scale.param_set_digits(3);
70 prop_scale.param_set_increments(0.01, 0.10);
72 concatenate_before_pwd2 = true;
74 groupSpecialBehavior = false;
75 }
77 LPEBendPath::~LPEBendPath()
78 {
80 }
82 void
83 LPEBendPath::doBeforeEffect (SPLPEItem *lpeitem)
84 {
85 if(SP_IS_GROUP(lpeitem))
86 {
87 groupSpecialBehavior = true;
89 original_bbox(lpeitem);
90 }
91 }
93 Geom::Piecewise<Geom::D2<Geom::SBasis> >
94 LPEBendPath::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
95 {
96 using namespace Geom;
98 /* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */
100 Piecewise<D2<SBasis> > uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(bend_path.get_pwd2()),2,.1);
101 uskeleton = remove_short_cuts(uskeleton,.01);
102 Piecewise<D2<SBasis> > n = rot90(derivative(uskeleton));
103 n = force_continuity(remove_short_cuts(n,.1));
105 D2<Piecewise<SBasis> > patternd2 = make_cuts_independant(pwd2_in);
106 Piecewise<SBasis> x = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]);
107 Piecewise<SBasis> y = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : Piecewise<SBasis>(patternd2[1]);
109 //We use the group bounding box size or the path bbox size to translate well x and y
110 if(groupSpecialBehavior == false)
111 {
112 boundingbox_X = bounds_exact(x);
113 boundingbox_Y = bounds_exact(y);
114 }
115 x-= vertical_pattern.get_value() ? boundingbox_Y.min() : boundingbox_X.min();
116 y-= vertical_pattern.get_value() ? boundingbox_X.middle() : boundingbox_Y.middle();
118 double scaling = uskeleton.cuts.back()/boundingbox_X.extent();
120 if (scaling != 1.0) {
121 x*=scaling;
122 }
124 if ( scale_y_rel.get_value() ) {
125 y*=(scaling*prop_scale);
126 } else {
127 if (prop_scale != 1.0) y *= prop_scale;
128 }
131 Piecewise<D2<SBasis> > output = compose(uskeleton,x) + y*compose(n,x);
132 return output;
133 }
135 void
136 LPEBendPath::resetDefaults(SPItem * item)
137 {
138 original_bbox(SP_LPE_ITEM(item));
140 Geom::Point start(boundingbox_X.min(), (boundingbox_Y.max()+boundingbox_Y.min())/2);
141 Geom::Point end(boundingbox_X.max(), (boundingbox_Y.max()+boundingbox_Y.min())/2);
143 if ( Geom::are_near(start,end) ) {
144 end += Geom::Point(1.,0.);
145 }
147 Geom::Path path;
148 path.start( start );
149 path.appendNew<Geom::LineSegment>( end );
150 bend_path.param_set_and_write_new_value( path.toPwSb() );
151 }
153 void
154 LPEBendPath::transform_multiply(Geom::Matrix const& postmul, bool set)
155 {
156 // TODO: implement correct transformation instead of this default behavior
157 Effect::transform_multiply(postmul, set);
158 }
161 } // namespace LivePathEffect
162 } /* namespace Inkscape */
164 /*
165 Local Variables:
166 mode:c++
167 c-file-style:"stroustrup"
168 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
169 indent-tabs-mode:nil
170 fill-column:99
171 End:
172 */
173 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :