1 files changed, 182 insertions, 0 deletions
diff --git a/src/live_effects/lpe-parallel.cpp b/src/live_effects/lpe-parallel.cpp
new file mode 100644
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--- /dev/null
+++ b/src/live_effects/lpe-parallel.cpp
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** \file
+ * LPE <parallel> implementation
+ */
+/*
+ * Authors:
+ *   Maximilian Albert
+ *
+ * Copyright (C) Johan Engelen 2007-2012 <j.b.c.engelen@alumnus.utwente.nl>
+ * Copyright (C) Maximilian Albert 2008 <maximilian.albert@gmail.com>
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "lpe-parallel.h"
+
+#include "display/curve.h"
+
+#include "object/sp-shape.h"
+
+#include "ui/knot/knot-holder.h"
+#include "ui/knot/knot-holder-entity.h"
+
+// TODO due to internal breakage in glibmm headers, this must be last:
+#include <glibmm/i18n.h>
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+namespace Pl {
+
+class KnotHolderEntityLeftEnd : public LPEKnotHolderEntity {
+public:
+    KnotHolderEntityLeftEnd(LPEParallel *effect) : LPEKnotHolderEntity(effect) {};
+    void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
+    Geom::Point knot_get() const override;
+};
+
+class KnotHolderEntityRightEnd : public LPEKnotHolderEntity {
+public:
+    KnotHolderEntityRightEnd(LPEParallel *effect) : LPEKnotHolderEntity(effect) {};
+    void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
+    Geom::Point knot_get() const override;
+};
+
+} // namespace Pl
+
+LPEParallel::LPEParallel(LivePathEffectObject *lpeobject) :
+    Effect(lpeobject),
+    // initialise your parameters here:
+    offset_pt(_("Offset"), _("Adjust the offset"), "offset_pt", &wr, this),
+    length_left(_("Length left:"), _("Specifies the left end of the parallel"), "length-left", &wr, this, 150),
+    length_right(_("Length right:"), _("Specifies the right end of the parallel"), "length-right", &wr, this, 150)
+{
+    show_orig_path = true;
+    _provides_knotholder_entities = true;
+
+    registerParameter(&offset_pt);
+    registerParameter(&length_left);
+    registerParameter(&length_right);
+}
+
+LPEParallel::~LPEParallel()
+= default;
+
+void
+LPEParallel::doOnApply (SPLPEItem const* lpeitem)
+{
+    auto shape = dynamic_cast<SPShape const *>(lpeitem);
+    if (!shape) {
+        g_warning("LPE parallel can only be applied to shapes (not groups).");
+        SPLPEItem * item = const_cast<SPLPEItem*>(lpeitem);
+        item->removeCurrentPathEffect(false);
+        return;
+    }
+    SPCurve const *curve = shape->curve();
+
+    A = *(curve->first_point());
+    B = *(curve->last_point());
+    dir = unit_vector(B - A);
+    Geom::Point offset = (A + B)/2 + dir.ccw() * 100;
+    offset_pt.param_update_default(offset);
+    offset_pt.param_setValue(offset, true);
+}
+
+Geom::Piecewise<Geom::D2<Geom::SBasis> >
+LPEParallel::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
+{
+    using namespace Geom;
+
+    Piecewise<D2<SBasis> > output;
+
+    A = pwd2_in.firstValue();
+    B = pwd2_in.lastValue();
+    dir = unit_vector(B - A);
+
+    C = offset_pt - dir * length_left;
+    D = offset_pt + dir * length_right;
+
+    output = Piecewise<D2<SBasis> >(D2<SBasis>(SBasis(C[X], D[X]), SBasis(C[Y], D[Y])));
+    
+    return output + dir;
+}
+
+void LPEParallel::addKnotHolderEntities(KnotHolder *knotholder, SPDesktop *desktop, SPItem *item) {
+    {
+        KnotHolderEntity *e = new Pl::KnotHolderEntityLeftEnd(this);
+        e->create(desktop, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:ParallelLeftEnd",
+                  _("Adjust the \"left\" end of the parallel"));
+        knotholder->add(e);
+    }
+    {
+        KnotHolderEntity *e = new Pl::KnotHolderEntityRightEnd(this);
+        e->create(desktop, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:ParallelRightEnd",
+                  _("Adjust the \"right\" end of the parallel"));
+        knotholder->add(e);
+    }
+};
+
+namespace Pl {
+
+void
+KnotHolderEntityLeftEnd::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint state)
+{
+    using namespace Geom;
+
+    LPEParallel *lpe = dynamic_cast<LPEParallel *>(_effect);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    double lambda = L2(s - lpe->offset_pt) * sgn(dot(s - lpe->offset_pt, lpe->dir));
+    lpe->length_left.param_set_value(-lambda);
+
+    sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), false, true);
+}
+
+void
+KnotHolderEntityRightEnd::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint state)
+{
+    using namespace Geom;
+
+    LPEParallel *lpe = dynamic_cast<LPEParallel *>(_effect);
+
+    Geom::Point const s = snap_knot_position(p, state);
+
+    double lambda = L2(s - lpe->offset_pt) * sgn(dot(s - lpe->offset_pt, lpe->dir));
+    lpe->length_right.param_set_value(lambda);
+
+    sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), false, true);
+}
+
+Geom::Point
+KnotHolderEntityLeftEnd::knot_get() const
+{
+    LPEParallel const *lpe = dynamic_cast<LPEParallel const*>(_effect);
+    return lpe->C;
+}
+
+Geom::Point
+KnotHolderEntityRightEnd::knot_get() const
+{
+    LPEParallel const *lpe = dynamic_cast<LPEParallel const*>(_effect);
+    return lpe->D;
+}
+
+} // namespace Pl
+
+/* ######################## */
+
+} //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 :