From bce2f84f17e5ee51d8222dc076ad013a68e58a7a Mon Sep 17 00:00:00 2001
From: cilix42 <cilix42@users.sourceforge.net>
Date: Mon, 19 May 2008 16:04:34 +0000
Subject: [PATCH] Forgot to add two files in commit #18667. Sorry for breaking
 the build for a minute!

---
 src/live_effects/lpe-tangent_to_curve.cpp | 101 ++++++++++++++++++++++
 src/live_effects/lpe-tangent_to_curve.h   |  51 +++++++++++
 2 files changed, 152 insertions(+)
 create mode 100644 src/live_effects/lpe-tangent_to_curve.cpp
 create mode 100644 src/live_effects/lpe-tangent_to_curve.h

diff --git a/src/live_effects/lpe-tangent_to_curve.cpp b/src/live_effects/lpe-tangent_to_curve.cpp
new file mode 100644
index 000000000..e7344c9dc
--- /dev/null
+++ b/src/live_effects/lpe-tangent_to_curve.cpp
@@ -0,0 +1,101 @@
+#define INKSCAPE_LPE_TANGENT_TO_CURVE_CPP
+/** \file
+ * Implementation of tangent-to-curve LPE.
+ */
+
+/*
+ * Authors:
+ *   Johan Engelen
+ *   Maximilian Albert
+ *
+ * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
+ * Copyright (C) Maximilian Albert 2008 <maximilian.albert@gmail.com>
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#include "live_effects/lpe-tangent_to_curve.h"
+// FIXME: The following are only needed to convert the path's SPCurve* to pwd2.
+//        There must be a more convenient way to achieve this.
+#include "sp-path.h"
+#include "display/curve.h"
+#include "libnr/n-art-bpath-2geom.h"
+
+#include <2geom/path.h>
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+/* FIXME: We should arguably make these member functions of LPETangentToCurve.
+          Is there an easy way to register member functions with knotholder?
+ */
+NR::Point attach_pt_get(SPItem *item) {
+    Inkscape::LivePathEffect::LPETangentToCurve *lpe =
+        (Inkscape::LivePathEffect::LPETangentToCurve *) sp_lpe_item_get_livepatheffect(SP_LPE_ITEM(item));
+
+    return lpe->ptA;
+}
+
+void attach_pt_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state) {
+    Inkscape::LivePathEffect::LPETangentToCurve *lpe =
+        (Inkscape::LivePathEffect::LPETangentToCurve *) sp_lpe_item_get_livepatheffect(SP_LPE_ITEM(item));
+
+    using namespace Geom;
+
+    // FIXME: There must be a better way of converting the path's SPCurve* to pwd2.
+    SPCurve *curve = sp_path_get_curve_for_edit (SP_PATH(item));
+    const NArtBpath *bpath = curve->get_bpath();
+    Piecewise<D2<SBasis> > pwd2;
+    std::vector<Geom::Path> pathv = BPath_to_2GeomPath(bpath);
+    for (unsigned int i=0; i < pathv.size(); i++) {
+        pwd2.concat(pathv[i].toPwSb());
+    }
+
+    double t0 = nearest_point(p.to_2geom(), pwd2);
+    lpe->t_attach.param_set_value(t0);
+
+    sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), true);
+}
+
+LPETangentToCurve::LPETangentToCurve(LivePathEffectObject *lpeobject) :
+    Effect(lpeobject),
+    t_attach(_("Location along curve"), _("Location of the point of attachment along the curve (between 0.0 and number-of-segments)"), "t_attach", &wr, this, 0.5)
+{
+    registerParameter( dynamic_cast<Parameter *>(&t_attach) );
+    registerKnotHolderHandle(attach_pt_set, attach_pt_get);
+}
+
+LPETangentToCurve::~LPETangentToCurve()
+{
+}
+
+Geom::Piecewise<Geom::D2<Geom::SBasis> >
+LPETangentToCurve::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
+{
+    using namespace Geom;
+    Piecewise<D2<SBasis> > output;
+
+    ptA = pwd2_in.valueAt(t_attach);
+    derivA = unit_vector(derivative(pwd2_in).valueAt(t_attach));
+
+    Point A = ptA - derivA * 100;
+    Point B = ptA + derivA * 100;
+
+    output = Piecewise<D2<SBasis> >(D2<SBasis>(Linear(A[X], B[X]), Linear(A[Y], B[Y])));
+
+    return output;
+}
+
+} //namespace LivePathEffect
+} /* namespace Inkscape */
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
diff --git a/src/live_effects/lpe-tangent_to_curve.h b/src/live_effects/lpe-tangent_to_curve.h
new file mode 100644
index 000000000..d8049c176
--- /dev/null
+++ b/src/live_effects/lpe-tangent_to_curve.h
@@ -0,0 +1,51 @@
+#ifndef INKSCAPE_LPE_TANGENT_TO_CURVE_H
+#define INKSCAPE_LPE_TANGENT_TO_CURVE_H
+
+/** \file
+ * LPE <tangent_to_curve> implementation, see lpe-tangent_to_curve.cpp.
+ */
+
+/*
+ * Authors:
+ *   Johan Engelen
+ *   Maximilian Albert
+ *
+ * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
+ * Copyright (C) Maximilian Albert 2008 <maximilian.albert@gmail.com>
+ *
+ * Released under GNU GPL, read the file 'COPYING' for more information
+ */
+
+#include "live_effects/effect.h"
+#include "live_effects/parameter/parameter.h"
+#include "live_effects/parameter/point.h"
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+class LPETangentToCurve : public Effect {
+public:
+    LPETangentToCurve(LivePathEffectObject *lpeobject);
+    virtual ~LPETangentToCurve();
+
+    virtual Geom::Piecewise<Geom::D2<Geom::SBasis> >
+      doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in);
+
+    /* the knotholder functions must be declared friends */
+    friend NR::Point attach_pt_get(SPItem *item);
+    friend void attach_pt_set(SPItem *item, NR::Point const &p, NR::Point const &origin, guint state);
+
+private:
+    ScalarParam t_attach;
+
+    Geom::Point ptA;
+    Geom::Point derivA;
+
+    LPETangentToCurve(const LPETangentToCurve&);
+    LPETangentToCurve& operator=(const LPETangentToCurve&);
+};
+
+} //namespace LivePathEffect
+} //namespace Inkscape
+
+#endif
-- 
2.30.2