Added the option to draw crossed out rectangles onto the image_display widget.

dlib/gui_widgets/widgets.cpp

@@ -5978,6 +5978,20 @@ namespace dlib
                 mfont->draw_string(c, r, itr->first, overlay_rects[i].color, 0, 
                                    std::string::npos, area);
             }
+
+            if (overlay_rects[i].crossed_out)
+            {
+                if (rect_is_selected && selected_rect == i)
+                {
+                    draw_line(c, orect.tl_corner(), orect.br_corner(),invert_pixel(overlay_rects[i].color), area);
+                    draw_line(c, orect.bl_corner(), orect.tr_corner(),invert_pixel(overlay_rects[i].color), area);
+                }
+                else
+                {
+                    draw_line(c, orect.tl_corner(), orect.br_corner(),overlay_rects[i].color, area);
+                    draw_line(c, orect.bl_corner(), orect.tr_corner(),overlay_rects[i].color, area);
+                }
+            }
         }
 
         // now draw all the overlay lines 
@@ -6039,6 +6053,15 @@ namespace dlib
             if (event_handler.is_set())
                 event_handler();
         }
+
+        if (is_printable && !hidden && enabled && rect_is_selected && (key == 'i'))
+        {
+            overlay_rects[selected_rect].crossed_out = !overlay_rects[selected_rect].crossed_out;
+            parent.invalidate_rectangle(rect);
+
+            if (event_handler.is_set())
+                event_handler();
+        }
     }
 
 // ----------------------------------------------------------------------------------------

dlib/gui_widgets/widgets.h

@@ -3292,24 +3292,25 @@ namespace dlib
 
         struct overlay_rect
         {
-            overlay_rect() { assign_pixel(color, 0);}
+            overlay_rect() :crossed_out(false) { assign_pixel(color, 0);}
 
             template <typename pixel_type>
             overlay_rect(const rectangle& r, pixel_type p) 
-                : rect(r) { assign_pixel(color, p); }
+                : rect(r),crossed_out(false) { assign_pixel(color, p); }
 
             template <typename pixel_type>
             overlay_rect(const rectangle& r, pixel_type p, const std::string& l) 
-                : rect(r),label(l) { assign_pixel(color, p); }
+                : rect(r),label(l),crossed_out(false) { assign_pixel(color, p); }
 
             template <typename pixel_type>
             overlay_rect(const rectangle& r, pixel_type p, const std::string& l, const std::map<std::string,point>& parts_) 
-                : rect(r),label(l),parts(parts_) { assign_pixel(color, p); }
+                : rect(r),label(l),parts(parts_),crossed_out(false) { assign_pixel(color, p); }
 
             rectangle rect;
             rgb_alpha_pixel color;
             std::string label;
             std::map<std::string,point> parts;
+            bool crossed_out;
         };
 
         struct overlay_line

dlib/gui_widgets/widgets_abstract.h

@@ -2394,12 +2394,16 @@ namespace dlib
                     Moreover, the rectangle can have sub-parts. Each part is listed
                     in the parts member variable.  This variable maps the name of the
                     part to its position.
+
+                    Rectangles with crossed_out == true will be drawn with an X through
+                    them.
             !*/
 
             rectangle rect;
             rgb_alpha_pixel color;
             std::string label;
             std::map<std::string,point> parts;
+            bool crossed_out;
 
             overlay_rect(
             ); 
@@ -2408,6 +2412,7 @@ namespace dlib
                     - #color == rgb_alpha_pixel(0,0,0,0) 
                     - #rect == rectangle()
                     - #label.size() == 0
+                    - #crossed_out == false
             !*/
 
             template <typename pixel_type>
@@ -2420,6 +2425,7 @@ namespace dlib
                     - #rect == r
                     - performs assign_pixel(color, p) 
                     - #label.size() == 0
+                    - #crossed_out == false
             !*/
 
             template <typename pixel_type>
@@ -2433,6 +2439,7 @@ namespace dlib
                     - #rect == r
                     - performs assign_pixel(color, p)
                     - #label == l
+                    - #crossed_out == false
             !*/
 
             template <typename pixel_type>
@@ -2448,6 +2455,7 @@ namespace dlib
                     - performs assign_pixel(color, p)
                     - #label == l
                     - #parts == parts_
+                    - #crossed_out == false
             !*/
 
         };