Lingo Dictionary > G-K > on isOKToAttach

 

on isOKToAttach

Syntax

on isOKToAttach me, spriteType, spriteNum

Description

Built-in handler; you can add this handler to a behavior in order to check the type of sprite the behavior is being attached to and prevent the behavior from being attached to inappropriate sprite types.

When the behavior is attached to a sprite, the handler executes and Director passes to it the type of the sprite and its sprite number. The me argument contains a reference to the behavior that is being attached to the sprite.

This handler runs before the on getPropertyDescriptionList handler.

The Lingo author can check for two types of sprites. #graphic includes all graphic cast members, such as shapes, bitmaps, digital video, text, and so on. #script indicates the behavior was attached to the script channel. In this case, the spriteNum is 1.

For each of these sprite types, the handler must return TRUE or FALSE. A value of TRUE indicates that the behavior can be attached to the sprite. A value of FALSE prevents the behavior from being attached to the sprite.

If the behavior contains no on isOKToAttach handler, then the behavior can be attached to any sprite or frame.

This handler will only be called during the initial attachment of the behavior to the sprite or script channel and will not be called again when any other changes are made to the sprite.

Example

This statement checks the sprite type the behavior is being attached to and returns TRUE for any graphic sprite except a shape and FALSE for the script channel:

on isOKToAttach me, spriteType, spriteNum
	case spriteType of
		#graphic: -- any graphic sprite type
			return sprite(spriteNum).member.type <> #shape
			-- works for everything but shape cast members
		#script: --the frame script channel
			return FALSE -- doesn't work as a frame script
	end case

end