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 "svg/svg.h"
16 #include "ui/widget/scalar.h"
18 #include <2geom/sbasis.h>
19 #include <2geom/sbasis-geometric.h>
20 #include <2geom/bezier-to-sbasis.h>
21 #include <2geom/sbasis-to-bezier.h>
22 #include <2geom/d2.h>
23 #include <2geom/piecewise.h>
25 #include <algorithm>
26 using std::vector;
29 /* Theory in e-mail from J.F. Barraud
30 Let B be the skeleton path, and P the pattern (the path to be deformed).
32 P is a map t --> P(t) = ( x(t), y(t) ).
33 B is a map t --> B(t) = ( a(t), b(t) ).
35 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
36 U(s) is s itself.
38 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).
40 The basic deformation associated to B is then given by:
42 (x,y) --> U(x)+y*N(x)
44 (i.e. we go for distance x along the path, and then for distance y along the normal)
46 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
47 first) but I think we can first forget about them.
48 */
50 namespace Inkscape {
51 namespace LivePathEffect {
53 LPEBendPath::LPEBendPath(LivePathEffectObject *lpeobject) :
54 Effect(lpeobject),
55 bend_path(_("Bend path:"), _("Path along which to bend the original path"), "bendpath", &wr, this, "M0,0 L1,0"),
56 prop_scale(_("Width:"), _("Width of the path"), "prop_scale", &wr, this, 1),
57 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),
58 vertical_pattern(_("Original path is vertical"), _("Rotates the original 90 degrees, before bending it along the bend path"), "vertical", &wr, this, false)
59 {
60 registerParameter( dynamic_cast<Parameter *>(&bend_path) );
61 registerParameter( dynamic_cast<Parameter *>(&prop_scale) );
62 registerParameter( dynamic_cast<Parameter *>(&scale_y_rel) );
63 registerParameter( dynamic_cast<Parameter *>(&vertical_pattern) );
65 prop_scale.param_set_digits(3);
66 prop_scale.param_set_increments(0.01, 0.10);
68 concatenate_before_pwd2 = true;
69 }
71 LPEBendPath::~LPEBendPath()
72 {
74 }
76 void
77 LPEBendPath::doBeforeEffect (SPLPEItem *lpeitem)
78 {
79 // get the item bounding box
80 original_bbox(lpeitem);
81 }
83 Geom::Piecewise<Geom::D2<Geom::SBasis> >
84 LPEBendPath::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
85 {
86 using namespace Geom;
88 /* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */
90 if (bend_path.changed) {
91 uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(bend_path.get_pwd2()),2,.1);
92 uskeleton = remove_short_cuts(uskeleton,.01);
93 n = rot90(derivative(uskeleton));
94 n = force_continuity(remove_short_cuts(n,.1));
96 bend_path.changed = false;
97 }
99 D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(pwd2_in);
100 Piecewise<SBasis> x = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]);
101 Piecewise<SBasis> y = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : Piecewise<SBasis>(patternd2[1]);
103 Interval bboxHorizontal = vertical_pattern.get_value() ? boundingbox_Y : boundingbox_X;
104 Interval bboxVertical = vertical_pattern.get_value() ? boundingbox_X : boundingbox_Y;
106 //We use the group bounding box size or the path bbox size to translate well x and y
107 x-= bboxHorizontal.min();
108 y-= bboxVertical.middle();
110 double scaling = uskeleton.cuts.back()/bboxHorizontal.extent();
112 if (scaling != 1.0) {
113 x*=scaling;
114 }
116 if ( scale_y_rel.get_value() ) {
117 y*=(scaling*prop_scale);
118 } else {
119 if (prop_scale != 1.0) y *= prop_scale;
120 }
123 Piecewise<D2<SBasis> > output = compose(uskeleton,x) + y*compose(n,x);
124 return output;
125 }
127 void
128 LPEBendPath::resetDefaults(SPItem * item)
129 {
130 Effect::resetDefaults(item);
132 original_bbox(SP_LPE_ITEM(item));
134 Geom::Point start(boundingbox_X.min(), (boundingbox_Y.max()+boundingbox_Y.min())/2);
135 Geom::Point end(boundingbox_X.max(), (boundingbox_Y.max()+boundingbox_Y.min())/2);
137 if ( Geom::are_near(start,end) ) {
138 end += Geom::Point(1.,0.);
139 }
141 Geom::Path path;
142 path.start( start );
143 path.appendNew<Geom::LineSegment>( end );
144 bend_path.set_new_value( path.toPwSb(), true );
145 }
148 } // namespace LivePathEffect
149 } /* namespace Inkscape */
151 /*
152 Local Variables:
153 mode:c++
154 c-file-style:"stroustrup"
155 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
156 indent-tabs-mode:nil
157 fill-column:99
158 End:
159 */
160 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :