# wx.UpdateUIEvent¶

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 wx.UpdateUIEvent.Check . 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, wx.Menu.UpdateUI 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 wx.IdleEvent handler for a window does not affect this because the events are sent from wx.Window.OnInternalIdle 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.

## Events Emitted by this Class¶

Handlers bound for the following event types will receive a wx.UpdateUIEvent parameter.

• EVT_UPDATE_UI: Process a wxEVT_UPDATE_UI event for the command with the given id.

• EVT_UPDATE_UI_RANGE: Process a wxEVT_UPDATE_UI event for any command with id included in the given range.

## Class Hierarchy¶

Inheritance diagram for class UpdateUIEvent:

## Methods Summary¶

 __init__ Constructor. CanUpdate Returns True if it is appropriate to update (send UI update events to) this window. Check Check or uncheck the UI element. Enable Enable or disable the UI element. GetChecked Returns True if the UI element should be checked. GetEnabled Returns True if the UI element should be enabled. GetMode 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. GetSetChecked Returns True if the application has called Check . GetSetEnabled Returns True if the application has called Enable . GetSetShown Returns True if the application has called Show . GetSetText Returns True if the application has called SetText . GetShown Returns True if the UI element should be shown. GetText Returns the text that should be set for the UI element. GetUpdateInterval Returns the current interval between updates in milliseconds. IsCheckable Returns True if the UI element can be checked. ResetUpdateTime Used internally to reset the last-updated time to the current time. SetMode Specify how wxWidgets will send update events: to all windows, or only to those which specify that they will process the events. SetText Sets the text for this UI element. SetUpdateInterval Sets the interval between updates in milliseconds. Show Show or hide the UI element.

## Class API¶

class wx.UpdateUIEvent(CommandEvent)

Possible constructors:

UpdateUIEvent(commandId=0)


This class is used for pseudo-events which are called by wxWidgets to give an application the chance to update various user interface elements.

### Methods¶

__init__(self, commandId=0)

Constructor.

Parameters

commandId (wx.WindowID) –

static CanUpdate(window)

Returns True if it is appropriate to update (send UI update events to) this window.

This function looks at the mode used (see wx.UpdateUIEvent.SetMode ), the wx.WS_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 wx.UPDATE_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.

Parameters

window (wx.Window) –

Return type

bool

Check(self, check)

Check or uncheck the UI element.

Parameters

check (bool) –

Enable(self, enable)

Enable or disable the UI element.

Parameters

enable (bool) –

GetChecked(self)

Returns True if the UI element should be checked.

Return type

bool

GetEnabled(self)

Returns True if the UI element should be enabled.

Return type

bool

static GetMode()

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.

Return type

wx.UpdateUIMode

GetSetChecked(self)

Returns True if the application has called Check .

For wxWidgets internal use only.

Return type

bool

GetSetEnabled(self)

Returns True if the application has called Enable .

For wxWidgets internal use only.

Return type

bool

GetSetShown(self)

Returns True if the application has called Show .

For wxWidgets internal use only.

Return type

bool

GetSetText(self)

Returns True if the application has called SetText .

For wxWidgets internal use only.

Return type

bool

GetShown(self)

Returns True if the UI element should be shown.

Return type

bool

GetText(self)

Returns the text that should be set for the UI element.

Return type

string

static GetUpdateInterval()

Returns the current interval between updates in milliseconds.

Return type

long

IsCheckable(self)

Returns True if the UI element can be checked.

For the event handlers that can be used for multiple items, not all of which can be checked, this method can be useful to determine whether to call Check on the event object or not, i.e. the main use case for this method is:

def OnUpdateUI(self, event):
....
if event.IsCheckable()
event.Check(...some condition...)

Return type

bool

New in version 4.1/wxWidgets-3.1.5.

static ResetUpdateTime()

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.

static SetMode(mode)

Specify how wxWidgets will send update events: to all windows, or only to those which specify that they will process the events.

Parameters

mode (UpdateUIMode) – this parameter may be one of the wx.UpdateUIMode enumeration values. The default mode is wx.UPDATE_UI_PROCESS_ALL.

SetText(self, text)

Sets the text for this UI element.

Parameters

text (string) –

static SetUpdateInterval(updateInterval)

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 wx.Window.UpdateWindowUI at appropriate points in your application, such as when a dialog is about to be shown.

Parameters

updateInterval (long) –

Show(self, show)

Show or hide the UI element.

Parameters

show (bool) –

### Properties¶

Checked

Enabled

Shown

Text