Scrupp: Callbacks

Overview

At the beginning, Scrupp runs a Lua file which is chosen depending on the command line arguments. Read "Getting Started" for details. This file can run other Lua files, load any media type, define functions and so on. It has to define a table with the name 'main' which contains the callbacks.

Callbacks

render(delta): This callback function is mandatory. It is executed in every frame. Scrupp calls it with delta as the only argument. This parameter holds the time in milliseconds which has passed since the last call to this function. This time should be about 10 ms long because Scrupp tries to make constant 100 frames per second. This information can be used to time animations. The rendering of images should happen in this function.
resized(width, height): This callback function is optional. If a resizable window is created and it is resized, this function will be executed. It gets the new window width and height as arguments. This function should call scrupp.init() with these new values as arguments. Otherwise, it's not possible to render to new areas of the window.
keypressed(key): This callback function is optional. If a key is pressed, this function will be executed. Its only argument is the key constant. Read the section about Keyboard usage for details and an example.
keyreleased(key): This callback function is optional. If a key is released, this function will be executed. Its only argument is the key constant. Read the section about Keyboard usage for details and an example.
mousepressed(x, y, button): This callback function is optional. If a mouse button (including the mouse wheel) is pressed, this function will be executed. Read the section about Mouse usage for details and an example.
mousereleased(x, y, button): This callback function is optional. If a mouse button (including the mouse wheel) is released, this function will be executed. Read the section about Mouse usage for details and an example.

Example

-- create a resizable window
scrupp.init("Callback Test", 600, 400, 32, false, true)

local image = scrupp.addImage("path_to_image_file")

main = {
	render = function(dt)
		image:render(mouse.getX(), mouse.getY())
	end,
	
	resized = function(width, height)
		scrupp.init("Resized!", width, height, 32, false, true)
	end,
	
	mousepressed = function(x, y, button)
		print(button .." button pressed at "..x..", "..y)
	end,
	
	mousereleased = function(x, y, button)
		print(button .." button released at "..x..", "..y)
	end,
	
	keypressed = function(k)
		if k == "ESCAPE" then
			scrupp.exit()
		end
		print("key '" .. k .. "' pressed")
	end,
	
	keyreleased = function(k)
		print("key '" .. k .. "' released")
	end
}