clean up rect mess a bit before start working on other stuff

(bzr r2678)

4 files changed, 25 insertions, 33 deletions

diff --git a/src/display/sp-canvas.cpp b/src/display/sp-canvas.cpp
index 559515e03..94eb984a3 100644
--- a/src/display/sp-canvas.cpp
+++ b/src/display/sp-canvas.cpp
@@ -751,8 +751,8 @@ sp_canvas_group_update (SPCanvasItem *item, NR::Matrix const &affine, unsigned i
         item->x2 = bounds->max()[NR::X];
         item->y2 = bounds->max()[NR::Y];
     } else {
-        item->x1 = item->x2 = corners.midpoint()[NR::X];
-        item->y1 = item->y2 = corners.midpoint()[NR::Y];
+        // FIXME ?
+        item->x1 = item->x2 = item->y1 = item->y2 = 0;
     }
 }
 
diff --git a/src/libnr/nr-convex-hull.h b/src/libnr/nr-convex-hull.h
index fef885f00..51dabcf07 100644
--- a/src/libnr/nr-convex-hull.h
+++ b/src/libnr/nr-convex-hull.h
@@ -17,39 +17,32 @@ namespace NR {
 
 class ConvexHull {
 public:
-	explicit ConvexHull(Point const &p)
-    : _initial(p) {}
+    ConvexHull() : _bounds() {}
+	explicit ConvexHull(Point const &p) : _bounds(Rect(p, p)) {}
 
-    Point midpoint() const {
+    Maybe<Point> midpoint() const {
         if (_bounds) {
             return _bounds->midpoint();
         } else {
-            return _initial;
+            return Nothing();
         }
     }
 
 	void add(Point const &p) {
         if (_bounds) {
 		    _bounds->expandTo(p);
-        } else if ( p != _initial ) {
-            _bounds = Rect(_initial, p);
+        } else {
+            _bounds = Rect(p, p);
         }
 	}
-	void add(Rect const &p) {
+	void add(Rect const &r) {
 		// Note that this is a hack.  when convexhull actually works
 		// you will need to add all four points.
-		if (_bounds) {
-            _bounds = union_bounds(*_bounds, p);
-        } else {
-            _bounds = p;
-            _bounds->expandTo(_initial);
-        }
+        _bounds = union_bounds(_bounds, r);
 	}
 	void add(ConvexHull const &h) {
         if (h._bounds) {
             add(*h._bounds);
-        } else {
-            add(h._initial);
         }
 	}
 
@@ -58,8 +51,7 @@ public:
 	}
 	
 private:
-    Point _initial;
-	Maybe<Rect> _bounds;
+    Maybe<Rect> _bounds;
 };
 
 } /* namespace NR */
diff --git a/src/libnr/nr-rect.cpp b/src/libnr/nr-rect.cpp
index d4ba14e1a..f3eb498af 100644
--- a/src/libnr/nr-rect.cpp
+++ b/src/libnr/nr-rect.cpp
@@ -245,13 +245,7 @@ namespace NR {
 Rect::Rect(const Point &p0, const Point &p1)
 : _min(std::min(p0[X], p1[X]), std::min(p0[Y], p1[Y])),
   _max(std::max(p0[X], p1[X]), std::max(p0[Y], p1[Y]))
-{
-    if (0) {
-    if ( _min[X] == _max[X] || _min[Y] == _max[Y] ) {
-        throw EmptyRectangle();
-    }
-    }
-}
+{}
 
 /** returns the four corners of the rectangle in the correct winding order */
 Point Rect::corner(unsigned i) const {
diff --git a/src/libnr/nr-rect.h b/src/libnr/nr-rect.h
index 6ae1e4e99..1062df955 100644
--- a/src/libnr/nr-rect.h
+++ b/src/libnr/nr-rect.h
@@ -28,16 +28,13 @@
 namespace NR {
     struct Matrix;
 
-class EmptyRectangle : public std::logic_error {
-public:
-    EmptyRectangle() : logic_error("Attempt to create empty rectangle") {}
-};
-
 /** A rectangle is always aligned to the X and Y axis.  This means it
  * can be defined using only 4 coordinates, and determining
  * intersection is very efficient.  The points inside a rectangle are
- * min[dim] <= _pt[dim] <= max[dim].  Emptiness, in the sense of having
- * a zero area, is not permitted.  Infinities are, however. */
+ * min[dim] <= _pt[dim] <= max[dim].  A rectangle may be empty, in the
+ * sense of having zero area, but it will always contain at least one
+ * point.  Infinities are also permitted.
+ */
 class Rect {
 public:
     Rect() : _min(-_inf(), -_inf()), _max(_inf(), _inf()) {}
@@ -56,6 +53,10 @@ public:
     /** returns the midpoint of this rect. */
     Point midpoint() const;
 
+    bool isEmpty(double epsilon=1e-6) const {
+        return isEmpty<X>(epsilon) || isEmpty<Y>(epsilon);
+    }
+
     bool intersects(Rect const &r) const {
         return intersects<X>(r) && intersects<Y>(r);
     }
@@ -152,6 +153,11 @@ private:
         return _max[axis] - _min[axis];
     }
 
+    template <NR::Dim2 axis>
+    bool isEmpty(double epsilon) const {
+        return extent<axis>() < epsilon;
+    }
+
     template <Dim2 axis>
     bool intersects(Rect const &r) const {
         return _max[axis] >= r._min[axis] && _min[axis] <= r._max[axis];