wxIdleEvent - Functions for wxIdleEvent class
Please see following description for synopsis
wxIdleEvent(3) Erlang Module Definition wxIdleEvent(3)
NAME
wxIdleEvent - Functions for wxIdleEvent class
DESCRIPTION
This class is used for idle events, which are generated when the system
becomes idle. Note that, unless you do something specifically, the idle
events are not sent if the system remains idle once it has become it,
e.g. only a single idle event will be generated until something else
resulting in more normal events happens and only then is the next idle
event sent again.
If you need to ensure a continuous stream of idle events, you can
either use requestMore/2 method in your handler or call ?wxWakeUpIdle()
periodically (for example from a timer event handler), but note that
both of these approaches (and especially the first one) increase the
system load and so should be avoided if possible.
By default, idle events are sent to all windows, including even the
hidden ones because they may be shown if some condition is met from
their wxEVT_IDLE (or related wxEVT_UPDATE_UI) handler. The children of
hidden windows do not receive idle events however as they can't change
their state in any way noticeable by the user. Finally, the global
wxApp (not implemented in wx) object also receives these events, as
usual, so it can be used for any global idle time processing.
If sending idle events to all windows is causing a significant overhead
in your application, you can call setMode/1 with the value wxI-
DLE_PROCESS_SPECIFIED, and set the wxWS_EX_PROCESS_IDLE extra window
style for every window which should receive idle events, all the other
ones will not receive them in this case.
Delayed Action Mechanism
wxIdleEvent can be used to perform some action "at slightly later
time". This can be necessary in several circumstances when, for what-
ever reason, something can't be done in the current event handler. For
example, if a mouse event handler is called with the mouse button
pressed, the mouse can be currently captured and some operations with
it - notably capturing it again - might be impossible or lead to unde-
sirable results. If you still want to capture it, you can do it from
wxEVT_IDLE handler when it is called the next time instead of doing it
immediately.
This can be achieved in two different ways: when using static event
tables, you will need a flag indicating to the (always connected) idle
event handler whether the desired action should be performed. The orig-
inally called handler would then set it to indicate that it should
indeed be done and the idle handler itself would reset it to prevent it
from doing the same action again.
Using dynamically connected event handlers things are even simpler as
the original event handler can simply wxEvtHandler::Connect() (not
implemented in wx) or wxEvtHandler::Bind() (not implemented in wx) the
idle event handler which would only be executed then and could
wxEvtHandler::Disconnect() (not implemented in wx) or
wxEvtHandler::Unbind() (not implemented in wx) itself.
See: Overview events, wxUpdateUIEvent, wxWindow::OnInternalIdle (not
implemented in wx)
This class is derived (and can use functions) from: wxEvent
wxWidgets docs: wxIdleEvent
EVENTS
Use wxEvtHandler:connect/3 with wxIdleEventType to subscribe to events
of this type.
DATA TYPES
wxIdleEvent() = wx:wx_object()
wxIdle() = #wxIdle{type = wxIdleEvent:wxIdleEventType()}
wxIdleEventType() = idle
EXPORTS
getMode() -> wx:wx_enum()
Static function returning a value specifying how wxWidgets will
send idle events: to all windows, or only to those which specify
that they will process the events.
See: setMode/1
requestMore(This) -> ok
Types:
This = wxIdleEvent()
requestMore(This, Options :: [Option]) -> ok
Types:
This = wxIdleEvent()
Option = {needMore, boolean()}
Tells wxWidgets that more processing is required.
This function can be called by an OnIdle handler for a window or
window event handler to indicate that wxApp::OnIdle should for-
ward the OnIdle event once more to the application windows.
If no window calls this function during OnIdle, then the appli-
cation will remain in a passive event loop (not calling OnIdle)
until a new event is posted to the application by the windowing
system.
See: moreRequested/1
moreRequested(This) -> boolean()
Types:
This = wxIdleEvent()
Returns true if the OnIdle function processing this event
requested more processing time.
See: requestMore/2
setMode(Mode) -> ok
Types:
Mode = wx:wx_enum()
Static function for specifying how wxWidgets will send idle
events: to all windows, or only to those which specify that they
will process the events.
wxWidgets team. wx 2.1.1 wxIdleEvent(3)