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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.