module Rubygame::Sprites::LimitGroup

LimitGroup is a mix-in module that extends Group to limit the number of sprites it can contain. If the limit has been reached, each new sprite will “push out” the oldest sprite, on a First-In-First-Out basis.

The limit can be set either when the LimitGroup is created, or at any time during execution. However, if you reduce the limit, excess sprites will not be removed until the next time a sprite is added. (You can work around this by pushing the last sprite in the group again; the duplicate will be removed.)

Please note that, because Rubygame::Sprites::Group#push is defined in terms of Rubygame::Sprites::Group#<<, both #<< and LimitGroup#push work properly, even though only #<< is defined.

Attributes

limit[RW]

Public Class Methods

extend_object(obj) click to toggle source

Defines and sets @limit = 1 when an existing object is extended.

Calls superclass method
# File lib/rubygame/sprite.rb, line 446
def LimitGroup.extend_object(obj)
        super
        obj.limit = 1
end
new(limit=1) click to toggle source

Initialize the LimitGroup and define @limit (as 1, by default).

# File lib/rubygame/sprite.rb, line 452
def initialize(limit=1)
        @limit = limit
end

Public Instance Methods

<<(sprite) click to toggle source

Add sprite to the LimitGroup, removing the oldest member if necessary to keep under the limit. If sprite is already in the LimitGroup, it will be moved to the top of the queue.

Calls superclass method
# File lib/rubygame/sprite.rb, line 459
def <<(sprite)
        if not include? sprite
                super(sprite)
                while length > @limit
                        self.slice!(0)
                end
        else # move sprite to the back of the queue
                self.delete(sprite)
                super(sprite)
        end
end