3 files changed, 22 insertions, 15 deletions
diff --git a/src/libnr/nr-forward.h b/src/libnr/nr-forward.h
index b12d141df..112313b24 100644
--- a/src/libnr/nr-forward.h
+++ b/src/libnr/nr-forward.h
@@ -21,6 +21,7 @@ class translate;
 
 class NArtBpath;
 struct NRBPath;
+struct const_NRBPath;
 struct NRPixBlock;
 struct NRRect;
 struct NRRectL;
diff --git a/src/libnr/nr-path.cpp b/src/libnr/nr-path.cpp
index 713cfe43d..734f3426d 100644
--- a/src/libnr/nr-path.cpp
+++ b/src/libnr/nr-path.cpp
@@ -20,7 +20,7 @@ static void nr_curve_bbox(NR::Point const p000, NR::Point const p001,
 			  NR::Point const p011, NR::Point const p111,
 			  NRRect *bbox);
 
-NRBPath *nr_path_duplicate_transform(NRBPath *d, NRBPath *s, NR::Matrix const *transform)
+NRBPath *nr_path_duplicate_transform(NRBPath *d, const_NRBPath *s, NR::Matrix const *transform)
 {
 	int i;
 
@@ -49,16 +49,17 @@ NRBPath *nr_path_duplicate_transform(NRBPath *d, NRBPath *s, NR::Matrix const *t
 	return d;
 }
 
-NRBPath *nr_path_duplicate_transform(NRBPath *d, NRBPath *s, NR::Matrix const transform) {
+NRBPath *nr_path_duplicate_transform(NRBPath *d, const_NRBPath *s, NR::Matrix const transform) {
 	NR::Matrix tr = transform;
 	return nr_path_duplicate_transform(d, s, &tr);
 }
 
-NArtBpath* nr_artpath_affine(NArtBpath *s, NR::Matrix const &aff) {
-	NRBPath bp, abp;
-	bp.path = s;
-	nr_path_duplicate_transform(&abp, &bp, aff);
-	return abp.path;
+NArtBpath* nr_artpath_affine(NArtBpath const *s, NR::Matrix const &aff) {
+    const_NRBPath bp;
+    bp.path = s;
+    NRBPath abp;
+    nr_path_duplicate_transform(&abp, &bp, aff);
+    return abp.path;
 }
 
 static void
@@ -212,7 +213,7 @@ nr_curve_bbox_wind_distance (NR::Coord x000, NR::Coord y000,
 }
 
 void
-nr_path_matrix_point_bbox_wind_distance (NRBPath *bpath, NR::Matrix const &m, NR::Point &pt,
+nr_path_matrix_point_bbox_wind_distance (const_NRBPath const *bpath, NR::Matrix const &m, NR::Point &pt,
 					     NRRect *bbox, int *wind, NR::Coord *dist,
 						 NR::Coord tolerance, NR::Rect *viewbox)
 {
@@ -449,7 +450,7 @@ nr_curve_bbox (NR::Coord x000, NR::Coord y000, NR::Coord x001, NR::Coord y001, N
 }
 
 void
-nr_path_matrix_bbox_union(NRBPath const *bpath, NR::Matrix const &m,
+nr_path_matrix_bbox_union(const_NRBPath *bpath, NR::Matrix const &m,
 			  NRRect *bbox)
 {
     using NR::X;
diff --git a/src/libnr/nr-path.h b/src/libnr/nr-path.h
index bf7369be4..5e8b0e48e 100644
--- a/src/libnr/nr-path.h
+++ b/src/libnr/nr-path.h
@@ -30,21 +30,26 @@
 #include <libnr/nr-forward.h>
 #include <libnr/nr-coord.h>
 
-NArtBpath* nr_artpath_affine(NArtBpath *s, NR::Matrix const &transform);
+NArtBpath* nr_artpath_affine(NArtBpath const *s, NR::Matrix const &transform);
 
+struct const_NRBPath {
+    NArtBpath const *path;
+};
 struct NRBPath {
-	NArtBpath *path;
+    NArtBpath *path;
+    operator const_NRBPath() { const_NRBPath bp = { path }; return bp; };
 };
 
-NRBPath *nr_path_duplicate_transform(NRBPath *d, NRBPath *s, NR::Matrix const *transform);
 
-NRBPath *nr_path_duplicate_transform(NRBPath *d, NRBPath *s, NR::Matrix const transform);
+NRBPath *nr_path_duplicate_transform(NRBPath *d, const_NRBPath *s, NR::Matrix const *transform);
+
+NRBPath *nr_path_duplicate_transform(NRBPath *d, const_NRBPath *s, NR::Matrix const transform);
 
-void nr_path_matrix_point_bbox_wind_distance (NRBPath *bpath, NR::Matrix const &m, NR::Point &pt,
+void nr_path_matrix_point_bbox_wind_distance (const_NRBPath const *bpath, NR::Matrix const &m, NR::Point &pt,
 					      NRRect *bbox, int *wind, NR::Coord *dist,
                      NR::Coord tolerance, NR::Rect *viewbox);
 
-void nr_path_matrix_bbox_union(NRBPath const *bpath, NR::Matrix const &m, NRRect *bbox);
+void nr_path_matrix_bbox_union(const_NRBPath *bpath, NR::Matrix const &m, NRRect *bbox);
 
 NArtBpath *nr_path_from_rect(NRRect const &r);