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NAME
wxUpdateUIEvent - Functions for wxUpdateUIEvent class
DESCRIPTION
This class is used for pseudo-events which are called by wxWidgets to give an application the chance to
update various user interface elements.
Without update UI events, an application has to work hard to check/uncheck, enable/disable, show/hide,
and set the text for elements such as menu items and toolbar buttons. The code for doing this has to be
mixed up with the code that is invoked when an action is invoked for a menu item or button.
With update UI events, you define an event handler to look at the state of the application and change UI
elements accordingly. wxWidgets will call your member functions in idle time, so you don't have to worry
where to call this code.
In addition to being a clearer and more declarative method, it also means you don't have to worry whether
you're updating a toolbar or menubar identifier. The same handler can update a menu item and toolbar
button, if the identifier is the same. Instead of directly manipulating the menu or button, you call
functions in the event object, such as check/2. wxWidgets will determine whether such a call has been
made, and which UI element to update.
These events will work for popup menus as well as menubars. Just before a menu is popped up,
wxMenu::UpdateUI (not implemented in wx) is called to process any UI events for the window that owns the
menu.
If you find that the overhead of UI update processing is affecting your application, you can do one or
both of the following:
Note that although events are sent in idle time, defining a wxIdleEvent handler for a window does not
affect this because the events are sent from wxWindow::OnInternalIdle (not implemented in wx) which is
always called in idle time.
wxWidgets tries to optimize update events on some platforms. On Windows and GTK+, events for menubar
items are only sent when the menu is about to be shown, and not in idle time.
See: Overview events
This class is derived (and can use functions) from: wxCommandEvent wxEvent
wxWidgets docs: wxUpdateUIEvent
EVENTS
Use wxEvtHandler:connect/3 with wxUpdateUIEventType to subscribe to events of this type.
DATA TYPES
wxUpdateUIEvent() = wx:wx_object()
wxUpdateUI() =
#wxUpdateUI{type = wxUpdateUIEvent:wxUpdateUIEventType()}
wxUpdateUIEventType() = update_ui
EXPORTS
canUpdate(Window) -> boolean()
Types:
Window = wxWindow:wxWindow()
Returns true if it is appropriate to update (send UI update events to) this window.
This function looks at the mode used (see setMode/1), the wxWS_EX_PROCESS_UI_UPDATES flag in
window, the time update events were last sent in idle time, and the update interval, to determine
whether events should be sent to this window now. By default this will always return true because
the update mode is initially wxUPDATE_UI_PROCESS_ALL and the interval is set to 0; so update
events will be sent as often as possible. You can reduce the frequency that events are sent by
changing the mode and/or setting an update interval.
See: resetUpdateTime/0, setUpdateInterval/1, setMode/1
check(This, Check) -> ok
Types:
This = wxUpdateUIEvent()
Check = boolean()
Check or uncheck the UI element.
enable(This, Enable) -> ok
Types:
This = wxUpdateUIEvent()
Enable = boolean()
Enable or disable the UI element.
show(This, Show) -> ok
Types:
This = wxUpdateUIEvent()
Show = boolean()
Show or hide the UI element.
getChecked(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the UI element should be checked.
getEnabled(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the UI element should be enabled.
getShown(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the UI element should be shown.
getSetChecked(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the application has called check/2.
For wxWidgets internal use only.
getSetEnabled(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the application has called enable/2.
For wxWidgets internal use only.
getSetShown(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the application has called show/2.
For wxWidgets internal use only.
getSetText(This) -> boolean()
Types:
This = wxUpdateUIEvent()
Returns true if the application has called setText/2.
For wxWidgets internal use only.
getText(This) -> unicode:charlist()
Types:
This = wxUpdateUIEvent()
Returns the text that should be set for the UI element.
getMode() -> wx:wx_enum()
Static function returning a value specifying how wxWidgets will send update events: to all
windows, or only to those which specify that they will process the events.
See: setMode/1
getUpdateInterval() -> integer()
Returns the current interval between updates in milliseconds.
The value -1 disables updates, 0 updates as frequently as possible.
See: setUpdateInterval/1
resetUpdateTime() -> ok
Used internally to reset the last-updated time to the current time.
It is assumed that update events are normally sent in idle time, so this is called at the end of
idle processing.
See: canUpdate/1, setUpdateInterval/1, setMode/1
setMode(Mode) -> ok
Types:
Mode = wx:wx_enum()
Specify how wxWidgets will send update events: to all windows, or only to those which specify that
they will process the events.
setText(This, Text) -> ok
Types:
This = wxUpdateUIEvent()
Text = unicode:chardata()
Sets the text for this UI element.
setUpdateInterval(UpdateInterval) -> ok
Types:
UpdateInterval = integer()
Sets the interval between updates in milliseconds.
Set to -1 to disable updates, or to 0 to update as frequently as possible. The default is 0.
Use this to reduce the overhead of UI update events if your application has a lot of windows. If
you set the value to -1 or greater than 0, you may also need to call wxWindow:updateWindowUI/2 at
appropriate points in your application, such as when a dialog is about to be shown.
wxWidgets team. wx 2.2.2.1 wxUpdateUIEvent(3erl)