Fix FilterUnits::get_matrix_units2pb() for bounding box case.

Fixes scaling in FilterMorphology when bounding box is used.
Update FilterOffset to also use function.

2 files changed, 7 insertions, 30 deletions

diff --git a/src/display/nr-filter-offset.cpp b/src/display/nr-filter-offset.cpp
index 93bab7d39..718dc4e2c 100644
--- a/src/display/nr-filter-offset.cpp
+++ b/src/display/nr-filter-offset.cpp
@@ -42,25 +42,11 @@ void FilterOffset::render_cairo(FilterSlot &slot)
     Geom::Rect vp = filter_primitive_area( slot.get_units() );
     slot.set_primitive_area(_output, vp); // Needed for tiling
 
-    // Handle bounding box case
-    double x = dx;
-    double y = dy;
-    if( slot.get_units().get_primitive_units() == SP_FILTER_UNITS_OBJECTBOUNDINGBOX ) {
-        Geom::OptRect bbox = slot.get_units().get_item_bbox();
-        if( bbox ) {
-            x *= (*bbox).width();
-            y *= (*bbox).height();
-        }
-    }
-
-    Geom::Affine trans = slot.get_units().get_matrix_user2pb();
-
-    Geom::Point offset(x, y);
-    offset *= trans;
-    offset[X] -= trans[4];
-    offset[Y] -= trans[5];
+    Geom::Affine p2pb = slot.get_units().get_matrix_primitiveunits2pb();
+    double x = dx * p2pb.expansionX();
+    double y = dy * p2pb.expansionY();
 
-    cairo_set_source_surface(ct, in, offset[X], offset[Y]);
+    cairo_set_source_surface(ct, in, x, y);
     cairo_paint(ct);
     cairo_destroy(ct);
 
diff --git a/src/display/nr-filter-units.cpp b/src/display/nr-filter-units.cpp
index 369deeb00..e242e3963 100644
--- a/src/display/nr-filter-units.cpp
+++ b/src/display/nr-filter-units.cpp
@@ -83,24 +83,15 @@ Geom::Affine FilterUnits::get_matrix_user2pb() const {
 
 Geom::Affine FilterUnits::get_matrix_units2pb(SPFilterUnits units) const {
     if ( item_bbox && (units == SP_FILTER_UNITS_OBJECTBOUNDINGBOX) ) {
+
         Geom::Affine u2pb = get_matrix_user2pb();
-        Geom::Point origo(item_bbox->min());
-        origo *= u2pb;
-        Geom::Point i_end(item_bbox->max()[X], item_bbox->min()[Y]);
-        i_end *= u2pb;
-        Geom::Point j_end(item_bbox->min()[X], item_bbox->max()[Y]);
-        j_end *= u2pb;
-
-        double len_i = sqrt((origo[X] - i_end[X]) * (origo[X] - i_end[X])
-                            + (origo[Y] - i_end[Y]) * (origo[Y] - i_end[Y]));
-        double len_j = sqrt((origo[X] - j_end[X]) * (origo[X] - j_end[X])
-                            + (origo[Y] - j_end[Y]) * (origo[Y] - j_end[Y]));
 
         /* TODO: make sure that user coordinate system (0,0) is in correct
          * place in pixblock coordinates */
-        Geom::Scale scaling(1.0 / len_i, 1.0 / len_j);
+        Geom::Scale scaling(item_bbox->width(), item_bbox->height());
         u2pb *= scaling;
         return u2pb;
+
     } else if (units == SP_FILTER_UNITS_USERSPACEONUSE) {
         return get_matrix_user2pb();
     } else {