wx.UpdateUIEvent

Inheritance diagram for wx.UpdateUIEvent:

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.

Derived From

• wx.CommandEvent
• wx.Event
• wx.Object

Remarks

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. 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:

1. Call SetMode with a value of wx.UPDATE_UI_PROCESS_SPECIFIED, and set the extra style wx.WS_EX_PROCESS_UPDATE_EVENTS for every window that should receive update events. No other windows will receive update events.
2. Call SetUpdateInterval with a millisecond value to set the delay between updates. You may need to call wx.Window.UpdateWindowUI at critical points, for example when a dialog is about to be shown, in case the user sees a slight delay before windows are updated.

Note

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.

Event Handling

Event Name	Description
wx.EVT_UPDATE_UI(id, func)	Process a wx.wxEVT_UPDATE_UI event for the command with the given id.
wx.EVT_UPDATE_UI_RANGE(id1, id2, func)	Process a wx.wxEVT_UPDATE_UI event for any command with id included in the given range.

Methods Summary

• __init__
• CanUpdate
• Check
• Enable
• GetChecked
• GetEnabled
• GetMode
• GetSetChecked
• GetSetEnabled
• GetSetShown
• GetSetText
• GetShown
• GetText
• GetUpdateInterval
• ResetUpdateTime
• SetMode
• SetText
• SetUpdateInterval
• Show

Properties Summary

• Enabled
• Shown
• Text

Class API

Methods

__init__(commandId=0)

Constructor.

Parameters:

• commandId (int)

Returns:

wx.UpdateUIEvent

---

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 SetMode), the wx.WS_EX_PROCESS_UPDATE_EVENTS 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)

Returns:

bool

See also

ResetUpdateTime, SetUpdateInterval, SetMode

---

Check(check)

Check or uncheck the UI element.

Parameters:

• check (bool)

---

Enable(enable)

Enable or disable the UI element.

Parameters:

• enable (bool)

---

GetChecked()

Returns True if the UI element should be checked.

Returns:

bool

---

GetEnabled()

Returns True if the UI element should be enabled.

Returns:

bool

---

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.

Returns:

int

See also

SetMode

---

GetSetChecked()

Returns True if the application has called Check. For wxWidgets internal use only.

Returns:

bool

---

GetSetEnabled()

Returns True if the application has called Enable. For wxWidgets internal use only.

Returns:

bool

---

GetSetShown()

Returns True if the application has called Show. For wxWidgets internal use only.

Returns:

bool

---

GetSetText()

Returns True if the application has called SetText. For wxWidgets internal use only.

Returns:

bool

---

GetShown()

Returns True if the UI element should be shown.

Returns:

bool

---

GetText()

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

Returns:

string

---

GetUpdateInterval()

Returns the current interval between updates in milliseconds. -1 disables updates, 0 updates as frequently as possible.

Returns:

long

See also

SetUpdateInterval

---

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.

See also

CanUpdate, SetUpdateInterval, SetMode

---

SetMode(mode)

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

mode may be one of the following values:

• wx.UPDATE_UI_PROCESS_ALL, Send UI update events to all windows
• wx.UPDATE_UI_PROCESS_SPECIFIED, Send UI update events to windows that have the wx.WS_EX_PROCESS_UI_UPDATES flag specified

The default is wx.UPDATE_UI_PROCESS_ALL.

Parameters:

• mode (int)

---

SetText(text)

Sets the text for this UI element.

Parameters:

• text (string)

---

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(show)

Show or hide the UI element.

Parameters:

• show (bool)

---

Properties

Enabled

See GetEnabled

Shown

See GetShown

Text

See GetText and SetText