Added some comments to the code I recently fixed to make it clearer what's going...

git-svn-id: http://svn.voria.com/code@399 1f10aa63-cdf2-0310-b900-c93c546f37ac

diff --git a/synfig-core/trunk/src/modules/mod_geometry/rectangle.cpp b/synfig-core/trunk/src/modules/mod_geometry/rectangle.cpp
index d0831e2..9925751 100644 (file)
--- a/synfig-core/trunk/src/modules/mod_geometry/rectangle.cpp
+++ b/synfig-core/trunk/src/modules/mod_geometry/rectangle.cpp
@@ -377,7 +377,7 @@ Rectangle::accelerated_render(Context context,Surface *surface,int quality, cons
                        surface->fill(color);
 
                        // Check for the case where there is nothing to render
-                       if(right-left<=0||bottom-top<=0)
+                       if (right <= left || bottom <= top)
                                return true;
 
                        desc.set_subwindow(left,top,right-left,bottom-top);
@@ -400,26 +400,31 @@ Rectangle::accelerated_render(Context context,Surface *surface,int quality, cons
                                if(cb)cb->error(strprintf(__FILE__"%d: Accelerated Renderer Failure",__LINE__));
                                return false;
                        }
+
                        Surface subimage;
 
-                       // Check for the case where there is nothing to render
-                       if(!(right-left<=0||bottom-top<=0))
+                       // Check for the case where there is something to render
+                       if (right > left && bottom > top)
                        {
+                               // save a copy of the overlapping region from surface into subimage
                                subimage.set_wh(right-left,bottom-top);
                                Surface::pen subimage_pen(subimage.begin());
                                surface->blit_to(subimage_pen,left,top,right-left,bottom-top);
                        }
 
+                       // fill surface with the rectangle's colour
                        Surface::alpha_pen surface_pen(surface->begin(),get_amount(),get_blend_method());
-
                        surface->fill(color,surface_pen,w,h);
 
-                       if(subimage)
+                       if (subimage)
                        {
+                               // copy the saved overlapping region back from subimage into surface
                                Surface::pen pen(surface->get_pen(left,top));
                                subimage.blit_to(pen);
                        }
-                       else return true;
+                       else
+                               // if there's no overlapping region, return now of the following code corrupts memory
+                               return true;
                }
 
                Surface::alpha_pen pen;