Events

This system module defines the EventSprite class which expands on the Sprite class to add definable event functions called handlers. These handlers are triggered under certain conditions such as a mouse being clicked. A special EventLoop is defined to act as a dedicated game loop that manages all of the event classes. Since the EventLoop is continuous until terminated by an eventLoop.stop call, you would have to design your game around using this module by making all Sprites in your game EventSprites.

Classes

Name	Description
EventHandler	Stores information about the action to take when responding to an Event.
KeyHandler	Stores the current state of a particular Key including whether it is Up, Down or being Held down.
EventSprite	Builds on the Sprite class to add event handlers that respond to events such as: onKey, onKeyDown, onKeyUp, onClick, etc.

Event Loop

Within the module, there is a special singleton class call eventLoop which is meant to only exist once. It governs the game loop and manages the responses to the triggered events. This is a dedicated game loop which will continue to execute until an event terminates the loop or program in some way.

Methods

Name	Description
run	The main game loop. Continues to execute until stop is called or the program is interrupted.
stop	Terminates the main loop on the next frame.
update	Called from the main loop each frame. Responsible for maintaining state of all events.
doAfter	Schedules a function call to happen at a later physical time.
cancelDoAfter	Removes a previously scheduled call by doAfter.

Example

	import "events"

	clear
	display(4).mode = displayMode.sprite
	spr = new events.EventSprite
	spr.image = file.loadImage("/sys/pics/Wumpus.png")
	spr.onKey = new events.KeyHandler
	spr.onKey["left"] = function
		self.x = self.x - 10
		if self.x < 50 then eventLoop.stop
	end function
	spr.onKey["right"] = function
		self.x = self.x + 10
	end function
	events.eventLoop.onKey["escape"] = function
		eventLoop.stop
	end function
	events.eventLoop.onKeyDown["space"] = function; print "space down"; end function
	events.eventLoop.onKey["space"] = function; print "space held"; end function
	events.eventLoop.onKeyUp["space"] = function; print "space up"; end function
	
	spr.onClick = function
		self.scale = 1.5
	end function
	spr.onDrag = function
		self.x = mouse.x
		self.y = mouse.y
	end function
	spr.onDragEnd = function
		self.scale = 1
	end function
	
	spr.x = 480
	spr.y = 320
	spr.start
	
	print "Click and drag, or press left/right."
	print "All event-driven.  (Esc to exit.)"
	
	events.eventLoop.run