Powerstroke: adjust control points when adding or deleting knots, to try and keep the shape a bit the same...

(bzr r10728)

4 files changed, 50 insertions, 5 deletions

diff --git a/src/live_effects/lpe-powerstroke.cpp b/src/live_effects/lpe-powerstroke.cpp
index 74a594a4b..56248907c 100644
--- a/src/live_effects/lpe-powerstroke.cpp
+++ b/src/live_effects/lpe-powerstroke.cpp
@@ -301,7 +301,7 @@ enum LineCuspType {
 static const Util::EnumData<unsigned> LineCuspTypeData[] = {
     {LINECUSP_BEVEL ,  N_("Beveled"),  "bevel"},
     {LINECUSP_ROUND ,  N_("Rounded"), "round"},
-    {LINECUSP_SHARP  , N_("Sharp"), "sharp"}
+// not yet supported    {LINECUSP_SHARP  , N_("Sharp"), "sharp"}
 };
 static const Util::EnumDataConverter<unsigned> LineCuspTypeConverter(LineCuspTypeData, sizeof(LineCuspTypeData)/sizeof(*LineCuspTypeData));
 
@@ -343,6 +343,12 @@ LPEPowerStroke::doOnApply(SPLPEItem *lpeitem)
     offset_points.param_set_and_write_new_value(points);
 }
 
+void
+LPEPowerStroke::adjustForNewPath(std::vector<Geom::Path> const & path_in)
+{
+    offset_points.recalculate_controlpoints_for_new_pwd2(path_in[0].toPwSb());
+}
+
 static bool compare_offsets (Geom::Point first, Geom::Point second)
 {
     return first[Geom::X] < second[Geom::X];
@@ -435,10 +441,9 @@ LPEPowerStroke::doEffect_path (std::vector<Geom::Path> const & path_in)
     // for now, only regard first subpath and ignore the rest
     Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2_in = path_in[0].toPwSb();
 
-    offset_points.set_pwd2(pwd2_in);
     Piecewise<D2<SBasis> > der = unitVector(derivative(pwd2_in));
     Piecewise<D2<SBasis> > n = rot90(der);
-    offset_points.set_pwd2_normal(n);
+    offset_points.set_pwd2(pwd2_in, n);
 
     std::vector<Geom::Point> ts = offset_points.data();
     if (sort_points) {
diff --git a/src/live_effects/lpe-powerstroke.h b/src/live_effects/lpe-powerstroke.h
index bcfbdadc0..6c005f792 100644
--- a/src/live_effects/lpe-powerstroke.h
+++ b/src/live_effects/lpe-powerstroke.h
@@ -29,6 +29,9 @@ public:
 
     virtual void doOnApply(SPLPEItem *lpeitem);
 
+    // methods called by path-manipulator upon edits
+    void adjustForNewPath(std::vector<Geom::Path> const & path_in);
+
 private:
     PowerStrokePointArrayParam offset_points;
     BoolParam sort_points;
diff --git a/src/live_effects/parameter/powerstrokepointarray.cpp b/src/live_effects/parameter/powerstrokepointarray.cpp
index 5139f0e41..fccbad7e5 100644
--- a/src/live_effects/parameter/powerstrokepointarray.cpp
+++ b/src/live_effects/parameter/powerstrokepointarray.cpp
@@ -76,6 +76,42 @@ void PowerStrokePointArrayParam::param_transform_multiply(Geom::Affine const& /*
 }
 
 
+/** call this method to recalculate the controlpoints such that they stay at the same location relative to the new path. Useful after adding/deleting nodes to the path.*/
+void
+PowerStrokePointArrayParam::recalculate_controlpoints_for_new_pwd2(Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
+{
+    if (!last_pwd2.empty()) {
+        if (last_pwd2.size() > pwd2_in.size()) {
+            // Path has become shorter: rescale offsets
+            double factor = (double)pwd2_in.size() / (double)last_pwd2.size();
+            for (unsigned int i = 0; i < _vector.size(); ++i) {
+                _vector[i][Geom::X] *= factor;
+            }
+        } else if (last_pwd2.size() < pwd2_in.size()) {
+            // Path has become longer: probably node added, maintain position of knots
+            Geom::Piecewise<Geom::D2<Geom::SBasis> > normal = rot90(unitVector(derivative(pwd2_in)));
+            for (unsigned int i = 0; i < _vector.size(); ++i) {
+                Geom::Point pt = _vector[i];
+                Geom::Point position = last_pwd2.valueAt(pt[Geom::X]) + pt[Geom::Y] * last_pwd2_normal.valueAt(pt[Geom::X]);
+                
+                double t = nearest_point(position, pwd2_in);
+                double offset = dot(position - pwd2_in.valueAt(t), normal.valueAt(t));
+                _vector[i] = Geom::Point(t, offset);
+            }
+        }
+
+        write_to_SVG();
+    }
+}
+
+void
+PowerStrokePointArrayParam::set_pwd2(Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in, Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_normal_in)
+{
+    last_pwd2 = pwd2_in;
+    last_pwd2_normal = pwd2_normal_in;
+}
+
+
 void
 PowerStrokePointArrayParam::set_oncanvas_looks(SPKnotShapeType shape, SPKnotModeType mode, guint32 color)
 {
diff --git a/src/live_effects/parameter/powerstrokepointarray.h b/src/live_effects/parameter/powerstrokepointarray.h
index d984a7de5..550866384 100644
--- a/src/live_effects/parameter/powerstrokepointarray.h
+++ b/src/live_effects/parameter/powerstrokepointarray.h
@@ -43,11 +43,12 @@ public:
     virtual bool providesKnotHolderEntities() { return true; }
     virtual void addKnotHolderEntities(KnotHolder *knotholder, SPDesktop *desktop, SPItem *item);
 
-    void set_pwd2(Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in) { last_pwd2 = pwd2_in; }
+    void set_pwd2(Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in, Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_normal_in);
     Geom::Piecewise<Geom::D2<Geom::SBasis> > const & get_pwd2() { return last_pwd2; }
-    void set_pwd2_normal(Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in) { last_pwd2_normal = pwd2_in; }
     Geom::Piecewise<Geom::D2<Geom::SBasis> > const & get_pwd2_normal() { return last_pwd2_normal; }
 
+    void recalculate_controlpoints_for_new_pwd2(Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in);
+
     friend class PowerStrokePointArrayParamKnotHolderEntity;
 
 private: