1 files changed, 149 insertions, 0 deletions
diff --git a/src/live_effects/lpe-spiro.cpp b/src/live_effects/lpe-spiro.cpp
new file mode 100644
index 0000000..e0464a2
--- /dev/null
+++ b/src/live_effects/lpe-spiro.cpp
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#define INKSCAPE_LPE_SPIRO_C
+
+/*
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "live_effects/lpe-spiro.h"
+
+#include "display/curve.h"
+#include <2geom/curves.h>
+#include "helper/geom-nodetype.h"
+#include "helper/geom-curves.h"
+
+#include "live_effects/spiro.h"
+
+// For handling un-continuous paths:
+#include "message-stack.h"
+#include "inkscape.h"
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+LPESpiro::LPESpiro(LivePathEffectObject *lpeobject) :
+    Effect(lpeobject)
+{
+}
+
+LPESpiro::~LPESpiro()
+= default;
+
+void
+LPESpiro::doEffect(SPCurve * curve)
+{
+    sp_spiro_do_effect(curve);
+}
+
+void sp_spiro_do_effect(SPCurve *curve){
+    using Geom::X;
+    using Geom::Y;
+
+    // Make copy of old path as it is changed during processing
+    Geom::PathVector const original_pathv = curve->get_pathvector();
+    guint len = curve->get_segment_count() + 2;
+
+    curve->reset();
+    Spiro::spiro_cp *path = g_new (Spiro::spiro_cp, len);
+    int ip = 0;
+
+    for(const auto & path_it : original_pathv) {
+        if (path_it.empty())
+            continue;
+
+        // start of path
+        {
+            Geom::Point p = path_it.initialPoint();
+            path[ip].x = p[X];
+            path[ip].y = p[Y];
+            path[ip].ty = '{' ;  // for closed paths, this is overwritten
+            ip++;
+        }
+
+        // midpoints
+        Geom::Path::const_iterator curve_it1 = path_it.begin();      // incoming curve
+        Geom::Path::const_iterator curve_it2 = ++(path_it.begin());         // outgoing curve
+        Geom::Path::const_iterator curve_endit = path_it.end_default(); // this determines when the loop has to stop
+
+        while ( curve_it2 != curve_endit )
+        {
+            /* This deals with the node between curve_it1 and curve_it2.
+             * Loop to end_default (so without last segment), loop ends when curve_it2 hits the end
+             * and then curve_it1 points to end or closing segment */
+            Geom::Point p = curve_it1->finalPoint();
+            path[ip].x = p[X];
+            path[ip].y = p[Y];
+
+            // Determine type of spiro node this is, determined by the tangents (angles) of the curves
+            // TODO: see if this can be simplified by using /helpers/geom-nodetype.cpp:get_nodetype
+            bool this_is_line = is_straight_curve(*curve_it1);
+            bool next_is_line = is_straight_curve(*curve_it2);
+
+            Geom::NodeType nodetype = Geom::get_nodetype(*curve_it1, *curve_it2);
+
+            if ( nodetype == Geom::NODE_SMOOTH || nodetype == Geom::NODE_SYMM )
+            {
+                if (this_is_line && !next_is_line) {
+                    path[ip].ty = ']';
+                } else if (next_is_line && !this_is_line) {
+                    path[ip].ty = '[';
+                } else {
+                    path[ip].ty = 'c';
+                }
+            } else {
+                path[ip].ty = 'v';
+            }
+
+            ++curve_it1;
+            ++curve_it2;
+            ip++;
+        }
+
+        // add last point to the spiropath
+        Geom::Point p = curve_it1->finalPoint();
+        path[ip].x = p[X];
+        path[ip].y = p[Y];
+        if (path_it.closed()) {
+            // curve_it1 points to the (visually) closing segment. determine the match between first and this last segment (the closing node)
+            Geom::NodeType nodetype = Geom::get_nodetype(*curve_it1, path_it.front());
+            switch (nodetype) {
+                case Geom::NODE_NONE: // can't happen! but if it does, it means the path isn't closed :-)
+                    path[ip].ty = '}';
+                    ip++;
+                    break;
+                case Geom::NODE_CUSP:
+                    path[0].ty = path[ip].ty = 'v';
+                    break;
+                case Geom::NODE_SMOOTH:
+                case Geom::NODE_SYMM:
+                    path[0].ty = path[ip].ty = 'c';
+                    break;
+            }
+        } else {
+            // set type to path closer
+            path[ip].ty = '}';
+            ip++;
+        }
+
+        // run subpath through spiro
+        int sp_len = ip;
+        Spiro::spiro_run(path, sp_len, *curve);
+        ip = 0;
+    }
+
+    g_free (path);
+}
+
+}; //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 :