Added some functions to the rectangle to make it easy

to get the corner points.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402872

dlib/geometry/rectangle.h

@@ -126,6 +126,18 @@ namespace dlib
             long bottom_
         ) { b = bottom_; }
 
+        const point tl_corner (
+        ) const { return point(left(), top()); }
+
+        const point bl_corner (
+        ) const { return point(left(), bottom()); } 
+
+        const point tr_corner (
+        ) const { return point(right(), top()); }
+
+        const point br_corner (
+        ) const { return point(right(), bottom()); }
+       
         unsigned long width (
         ) const 
         { 

dlib/geometry/rectangle_abstract.h

@@ -18,8 +18,8 @@ namespace dlib
 
             WHAT THIS OBJECT REPRESENTS
                 This object represents a rectangular region inside a Cartesian 
-                coordinate system.  The region is the rectangle with its upper 
-                left corner at position (left(),top()) and its lower right corner 
+                coordinate system.  The region is the rectangle with its top 
+                left corner at position (left(),top()) and its bottom right corner 
                 at (right(),bottom()).
 
                 Note that the origin of the coordinate system, i.e. (0,0), is located
@@ -191,6 +191,38 @@ namespace dlib
                 - #bottom() == bottom_
         !*/
 
+        const point tl_corner (
+        ) const;
+        /*!
+            ensures
+                - returns point(left(), top()) 
+                  (i.e. returns the top left corner point for this rectangle)
+        !*/
+
+        const point bl_corner (
+        ) const;
+        /*!
+            ensures
+                - returns point(left(), bottom()) 
+                  (i.e. returns the bottom left corner point for this rectangle)
+        !*/
+
+        const point tr_corner (
+        ) const;
+        /*!
+            ensures
+                - returns point(right(), top()) 
+                  (i.e. returns the top right corner point for this rectangle)
+        !*/
+
+        const point br_corner (
+        ) const;
+        /*!
+            ensures
+                - returns point(right(), bottom()) 
+                  (i.e. returns the bottom right corner point for this rectangle)
+        !*/
+
         bool is_empty (
         ) const;
         /*!

dlib/test/geometry.cpp

@@ -249,6 +249,26 @@ namespace
             DLIB_CASSERT((-v).z() == -5.0,"");
         }
 
+        {
+            rectangle rect;
+
+            point tl(2,3);
+            point tr(8,3);
+            point bl(2,9);
+            point br(8,9);
+
+            rect += tl;
+            rect += tr;
+            rect += bl;
+            rect += br;
+
+            DLIB_CASSERT(rect.tl_corner() == tl, "");
+            DLIB_CASSERT(rect.tr_corner() == tr, "");
+            DLIB_CASSERT(rect.bl_corner() == bl, "");
+            DLIB_CASSERT(rect.br_corner() == br, "");
+
+        }
+
     }