Compute farthest-from-center point correctly in Alt+rotation

(bzr r3723)

3 files changed, 15 insertions, 1 deletions

diff --git a/src/libnr/nr-rect.cpp b/src/libnr/nr-rect.cpp
index 72bced37b..f3036eff1 100644
--- a/src/libnr/nr-rect.cpp
+++ b/src/libnr/nr-rect.cpp
@@ -266,6 +266,18 @@ Point Rect::midpoint() const {
 	return ( _min + _max ) / 2;
 }
 
+Point Rect::cornerFarthestFrom(Point const &p) const {
+    Point m = midpoint();
+    unsigned i = 0;
+    if (p[X] < m[X]) {
+        i = 1;
+    }
+    if (p[Y] < m[Y]) {
+        i = 3 - i;
+    }
+    return corner(i);
+}
+
 /** returns a vector from topleft to bottom right. */
 Point Rect::dimensions() const {
 	return _max - _min;
diff --git a/src/libnr/nr-rect.h b/src/libnr/nr-rect.h
index 46aff13f4..439538e29 100644
--- a/src/libnr/nr-rect.h
+++ b/src/libnr/nr-rect.h
@@ -53,6 +53,8 @@ public:
     /** returns the midpoint of this rect. */
     Point midpoint() const;
 
+    Point cornerFarthestFrom(Point const &p) const;
+
     /** True iff either width or height is less than \a epsilon. */
     bool isEmpty(double epsilon=1e-6) const {
         return isEmpty<X>(epsilon) || isEmpty<Y>(epsilon);
diff --git a/src/selection-chemistry.cpp b/src/selection-chemistry.cpp
index a8cb4d4fe..251aa6dc0 100644
--- a/src/selection-chemistry.cpp
+++ b/src/selection-chemistry.cpp
@@ -1759,7 +1759,7 @@ sp_selection_rotate_screen(Inkscape::Selection *selection, gdouble angle)
 
     gdouble const zoom = selection->desktop()->current_zoom();
     gdouble const zmove = angle / zoom;
-    gdouble const r = NR::L2(bbox->max() - *center);
+    gdouble const r = NR::L2(bbox->cornerFarthestFrom(*center) - *center);
 
     gdouble const zangle = 180 * atan2(zmove, r) / M_PI;