sdlBasic library to poll input devices and generate discrete events like key_down, key_up & co.

events.sdlbas

' events.sdlbas: sdlBasic library to poll input devices
' and generate discrete events like key_down, key_up & co.

' 2019-05-07 No Time To Play <https://notimetoplay.org/>
' Use as you like; please keep the attribution if you will.

const no_event = 0
const key_down_event = 1
const key_up_event = 2
const mouse_down_event = 3
const mouse_up_event = 4

dim common event_wait_interval = 5

dim common mouse_event_x = -1
dim common mouse_event_y = -1
dim common mouse_event_button = 0

dim common key_event_code = -1

const num_event_keys = 60

dim common _event_key_codes[1 to num_event_keys]
dim common _event_key_state[1 to num_event_keys]

_event_key_codes[1] = k_1
_event_key_codes[2] = k_2
_event_key_codes[3] = k_3
_event_key_codes[4] = k_4
_event_key_codes[5] = k_5
_event_key_codes[6] = k_6
_event_key_codes[7] = k_7
_event_key_codes[8] = k_8
_event_key_codes[9] = k_9
_event_key_codes[10] = k_0

_event_key_codes[11] = k_f1
_event_key_codes[12] = k_f2
_event_key_codes[13] = k_f3
_event_key_codes[14] = k_f4
_event_key_codes[15] = k_f5
_event_key_codes[16] = k_f6
_event_key_codes[17] = k_f7
_event_key_codes[18] = k_f8
_event_key_codes[19] = k_f9
_event_key_codes[20] = k_f10
_event_key_codes[21] = k_f11
_event_key_codes[22] = k_f12
_event_key_codes[23] = k_f13
_event_key_codes[24] = k_f14
_event_key_codes[25] = k_f15

_event_key_codes[26] = k_esc
_event_key_codes[27] = k_space
_event_key_codes[28] = k_return
_event_key_codes[29] = k_tab
_event_key_codes[30] = k_backspace

_event_key_codes[31] = k_up
_event_key_codes[32] = k_down
_event_key_codes[33] = k_right
_event_key_codes[34] = k_left

_event_key_codes[35] = k_delete
_event_key_codes[36] = k_insert
_event_key_codes[37] = k_home
_event_key_codes[38] = k_end
_event_key_codes[39] = k_pageup
_event_key_codes[40] = k_pagedown

_event_key_codes[41] = k_minus
_event_key_codes[42] = k_plus
_event_key_codes[43] = k_comma
_event_key_codes[44] = k_period
_event_key_codes[45] = k_question

_event_key_codes[46] = k_kp0
_event_key_codes[47] = k_kp1
_event_key_codes[48] = k_kp2
_event_key_codes[49] = k_kp3
_event_key_codes[50] = k_kp4
_event_key_codes[51] = k_kp5
_event_key_codes[52] = k_kp6
_event_key_codes[53] = k_kp7
_event_key_codes[54] = k_kp8
_event_key_codes[55] = k_kp9

_event_key_codes[56] = k_kp_period
_event_key_codes[57] = k_kp_minus
_event_key_codes[58] = k_kp_plus
_event_key_codes[59] = k_kp_enter

_event_key_codes[60] = k_backquote

function poll_keyboard()
	dim i, k
	for i = 1 to num_event_keys
		k = _event_key_codes[i]
		if key(k) then
			if not _event_key_state[i] then
				_event_key_state[i] = true
				key_event_code = k
				return key_down_event
			end if
		else
			if _event_key_state[i] then
				_event_key_state[i] = false
				key_event_code = k
				return key_up_event
			end if
		end if
	next
	key_event_code = -1
	return no_event
end function

' Because the mousebutton built-in only returns the last button pressed,
' this function can't properly keep track of which button was released.
function poll_mouse()
	dim b = mousebutton
	if b > 0 then
		if mouse_event_button = b then
			return no_event
		else
			mouse_event_button = b
			mouse_event_x = mousex
			mouse_event_y = mousey
			return mouse_down_event
		end if
	else
		if mouse_event_button > 0 then
			mouse_event_button = 0
			mouse_event_x = mousex
			mouse_event_y = mousey
			return mouse_up_event
		else
			return no_event
		end if
	end if
end function

function poll_event()
	dim e = poll_keyboard
	if e <> no_event then
		return e
	else
		return poll_mouse
	end if
end function

function wait_for_event()
	dim e
	do
		e = poll_event
		if e <> no_event then
			exit do ' Don't return here directly or it freezes!
		else
			wait(event_wait_interval)
		end if
	loop
	return e
end function