[Patch 1758611] Daniel Neis Araújo's Sprite#undraw patch.

CREDITS

@@ -35,6 +35,11 @@
   Date::          received 2007-03-04; applied 2007-04-13 (r235).
 
 - <b>Johan Berntsson</b>
-  Email::         johan@microheaven.com
+  Email::         johan at microheaven.com
   Contribution::  Patch to add Mixer::Music class (music playback).
   Date::          2007-04-27 (r304).
+
+- <b>Daniel Neis Araujo</b> / danielneis
+  Email::         danielneis at gmail.com
+  Contribution::  Patch to add Sprite#undraw (based on UpdateGroup#undraw).
+  Date::          2007-07-29 (r460).

lib/rubygame/sprite.rb

@@ -197,6 +197,19 @@ def remove(*groups)
 				}
 			end
 
+
+			# call-seq: undraw(surface, background)  ->  Rect
+			# 
+			# 'Erase' the sprite from +surface+ by drawing over it with part of
+			# +background+. For best results, +background+ should be the same size
+			# as +surface+.
+			# 
+			# Returns a Rect representing the area of +surface+ which was affected.
+			# 
+			def undraw(dest, background)
+				background.blit(dest, @rect, @rect)
+			end			
+
 			# This method is meant to be overwritten by Sprite-based classes to
 			# define meaningful behavior. It can take any number of arguments you
 			# want, be called however often you want, and do whatever you want.
@@ -369,8 +382,7 @@ def draw(dest)
 			# over).
 			def undraw(dest,background)
 				self.each { |sprite|
-					background.blit(dest,sprite.rect,sprite.rect)
-					@dirty_rects.push(sprite.rect.dup)
+					@dirty_rects.push( sprite.undraw(dest, background) )
 				}
 			end
 		end # module UpdateGroup