glgui event

(glgui-event guis t x0 y0)

glgui-event process an input event. It loops over all guis provided and sends events to their widgets's input handlers. It is mainly found in the second function (the loop) of the main program declaration.

Parameter	Description
g	Graphical User Interface (GUI) or a list of GUIs
t	Event type, e.g. EVENT_KEYPRESS
x0	First argument of event, e.g. x coordinate pixels or keyboard character
y0	Second argument of event, e.g. y coordinate in pixels or modifier flags

If t is an EVENT_KEYPRESS or EVENT_KEYRELEASE event, y0 will have its bits set according to the modifier keys that are on, as described below.

Modifier key(s)	Constant name(s)	Constant value	Corresponding bit, where the rightmost bit is the zeroth bit
Control (macOS)	MODIFIER_CTRL_MAC	1	0
Control (Windows)/Command (macOS)	MODIFIER_CTRL/MODIFIER_CMD	2	1
Alt (Windows)/Option (macOS)	MODIFIER_ALT/MODIFIER_OPT	4	2
Shift	MODIFIER_SHIFT	8	3
Caps Lock	MODIFIER_CAPS	16	4
Function	MODIFIER_FN	32	5

Example

Example from apps/DemoRedSquare/main.scm

(lambda (t x y) 
  (if (= t EVENT_KEYPRESS) (begin (if (= x EVENT_KEYESCAPE) (terminate))))
  (glgui-event gui t x y)
)