| GUI.SetKeyEventHandler | Part of GUI module |
| Syntax | GUI.SetKeyEventHandler ( keyEventHandler : procedure x (ch : char))
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| Description | Sets the new default keystroke event handler. The keyEventHandler parameter is the name of a procedure that is called every time GUI.ProcessEvent is called and there is a keystroke which is not handled by any widget. The ch parameter in the keyEventHandler is the keystroke typed by the user. This procedure is often used to allow for more than one shortcut character for a given button.
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| Example | The following program draws a star or quits depening on the button. The Draw Star button can be activated by clicking on it or typing 'D', 'd', 'S', 's' or Ctrl+S. The Quit button can be activate by typing 'Q', 'q' or Ctrl+Q. The Draw Star button is also the default button. It is activated whenever the user presses ENTER.
import GUI
View.Set ("graphics:220;200")
procedure DrawStar
Draw.FillStar (25, 40, 175, 190, Rand.Int (10, 15))
end DrawStar
procedure KeyHandler (ch : char)
if ch = 'q' or ch = '^Q' then
Draw.Cls
GUI.Quit
elsif ch = 'd' or ch = '^d' or ch = 'S' or ch = 's' or ch = '^s' then
DrawStar
end if
end KeyHandler
GUI.SetKeyEventHandler (KeyHandler)
var button : int := GUI.CreateButtonFull (5, 5, 100, "Draw Star",
DrawStar, 0, 'D', true)
var quitButton : int := GUI.CreateButtonFull (115, 5, 100, "Quit",
GUI.Quit, 0, 'Q', false)
loop
exit when GUI.ProcessEvent
end loop
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| Status | Exported qualified. This means that you can only call the function by calling GUI.SetKeyEventHandler, not by calling SetKeyEventHandler.
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| See also | GUI.ProcessEvent.
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