RegisterEventHandler

registerEventHandler

Available since: v3.6

Registers an event handler function for a specific event.

Lua Syntax:

registerEventHandler(event, eventHandler [, eventFlags])

Arguments

event

"string" - The event which triggers the event handler to be called. Currently supported events: "mainLoop", "mouseEvent", "keyEvent", "animationStarted", "animationStopped", "textStarted", "textStopped".

eventHandler

"string" - The name of the lua function which is called when the event occurs.

The function for the events "animationStarted", "animationStopped", "textStarted" and "textStopped" should take exactly one argument which is the affected visionaire object.

There are no arguments for the "mainLoop" event handler.

The function for "mouseEvent" takes two arguments, the first one is the mouse event (see "eventFlags" parameter) and the second argument is the current mouse position (a table containing x- and y-position).

The function for "keyEvent" takes four arguments: eventType, character, keycode and modifiers. Return value must be true or false. If the function returns true, the key event will not be handled by the engine.

eventType: eEvtKeyDown (key pressed, can be fired multiple times for pressed key), eEvtKeyTextInput (text input, can be fired multiple times for pressed key) and eEvtKeyUp (key released, only fired once).

character: current text input of pressed key(s). This parameter only contains printable characters.

keycode: virtual keycode, only valid for eEvtKeyDown and eEvtKeyUp events. Can be used to query special keys like Esc or Shift.

modifiers: currently active key modifiers (e.g. Ctrl, Shift).

eventFlags

{int,...} - Can only be specified for "mouseEvent": a list of mouse events where the event handler is called.

Currently the following mouse events are supported: eEvtMouseMove, eEvtMouseLeftButtonDoubleClick, eEvtMouseLeftButtonDown, eEvtMouseLeftButtonUp, eEvtMouseLeftButtonHold, eEvtMouseLeftButtonHolding, eEvtMouseRightButtonDoubleClick, eEvtMouseRightButtonDown, eEvtMouseRightButtonUp, eEvtMouseMiddleButtonDown, eEvtMouseMiddleButtonUp, eEvtMouseWheelUp and eEvtMouseWheelDown. If no mouse event is specified then the event handler is registered for all mouse events.

Return Values

None.

Examples

Example 1: mainLoop

function onMainLoop()
-- do something
end

registerEventHandler("mainLoop", "onMainLoop")

Example 2: mouseEvent

function onMouseEvent(eventType, mousePosition)
  if eventType == eEvtMouseWheelUp or eventType == eEvtMouseWheelDown then
    -- mouse wheel was activated, do something
  end
end

registerEventHandler("mouseEvent", "onMouseEvent", {eEvtMouseMove, eEvtMouseLeftButtonDoubleClick, eEvtMouseLeftButtonDown, eEvtMouseLeftButtonUp, eEvtMouseLeftButtonHold, eEvtMouseLeftButtonHolding, eEvtMouseRightButtonDoubleClick, eEvtMouseRightButtonDown, eEvtMouseRightButtonUp, eEvtMouseMiddleButtonDown, eEvtMouseMiddleButtonUp, eEvtMouseWheelUp, eEvtMouseWheelDown})

Example 3: keyEvent

function keyboardHandler(eventType, character, keycode, modifiers)
  if eventType==eEvtKeyUp then
    print('key up: ' .. keycode)
    -- test for '0' with character parameter
    if character == '0' then print('0 released') end
    -- another option to test '0' key
    if keycode == 48 then print('0 released') end
  elseif eventType==eEvtKeyDown then
    print('key down: ' .. keycode)
  elseif eventType==eEvtKeyTextInput then
    -- this will also show more 'complex' unicode characters when multiple keys are used to generate a single character (e.g. Chinese characters)
    print('input: ' .. character)
  end
  if keycode == eKeyEscape then
    -- event will not be handled by engine. this means that also cutscenes can't be skipped with Escape key
    return true
  end
  return false -- key event will also be handled by engine
end

registerEventHandler("keyEvent", "keyboardHandler")