wxIdleEvent Class Reference

#include <wx/event.h>

Inheritance diagram for wxIdleEvent:

Detailed 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 wxIdleEvent::RequestMore 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 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 wxIdleEvent::SetMode with the value wxIDLE_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.

Events using this class

The following event handler macros redirect the events to member function handlers 'func' with prototypes like:

void handlerFuncName(wxIdleEvent& event)

Event macros:

• EVT_IDLE(func):
  Process a wxEVT_IDLE event.

Library:  wxBase

Category:  Events

Delayed Action Mechanism

wxIdleEvent can be used to perform some action "at slightly later time". This can be necessary in several circumstances when, for whatever 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 undesirable 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 originally 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() or wxEvtHandler::Bind() the idle event handler which would only be executed then and could wxEvtHandler::Disconnect() or wxEvtHandler::Unbind() itself.

See Also

Events and Event Handling, wxUpdateUIEvent, wxWindow::OnInternalIdle

Public Member Functions
	wxIdleEvent ()
	Constructor.
bool	MoreRequested () const
	Returns true if the OnIdle function processing this event requested more processing time.
void	RequestMore (bool needMore=true)
	Tells wxWidgets that more processing is required.
Public Member Functions inherited from wxEvent
	wxEvent (int id=0, wxEventType eventType=wxEVT_NULL)
	Constructor.
virtual wxEvent *	Clone () const =0
	Returns a copy of the event.
wxObject *	GetEventObject () const
	Returns the object (usually a window) associated with the event, if any.
wxEventType	GetEventType () const
	Returns the identifier of the given event type, such as wxEVT_BUTTON.
virtual wxEventCategory	GetEventCategory () const
	Returns a generic category for this event.
int	GetId () const
	Returns the identifier associated with this event, such as a button command id.
wxObject *	GetEventUserData () const
	Return the user data associated with a dynamically connected event handler.
bool	GetSkipped () const
	Returns true if the event handler should be skipped, false otherwise.
long	GetTimestamp () const
	Gets the timestamp for the event.
bool	IsCommandEvent () const
	Returns true if the event is or is derived from wxCommandEvent else it returns false.
void	ResumePropagation (int propagationLevel)
	Sets the propagation level to the given value (for example returned from an earlier call to wxEvent::StopPropagation).
void	SetEventObject (wxObject *object)
	Sets the originating object.
void	SetEventType (wxEventType type)
	Sets the event type.
void	SetId (int id)
	Sets the identifier associated with this event, such as a button command id.
void	SetTimestamp (long timeStamp=0)
	Sets the timestamp for the event.
bool	ShouldPropagate () const
	Test if this event should be propagated or not, i.e. if the propagation level is currently greater than 0.
void	Skip (bool skip=true)
	This method can be used inside an event handler to control whether further event handlers bound to this event will be called after the current one returns.
int	StopPropagation ()
	Stop the event from propagating to its parent window.
Public Member Functions inherited from wxObject
	wxObject ()
	Default ctor; initializes to NULL the internal reference data.
	wxObject (const wxObject &other)
	Copy ctor.
virtual	~wxObject ()
	Destructor.
virtual wxClassInfo *	GetClassInfo () const
	This virtual function is redefined for every class that requires run-time type information, when using the wxDECLARE_CLASS macro (or similar).
wxObjectRefData *	GetRefData () const
	Returns the wxObject::m_refData pointer, i.e. the data referenced by this object.
bool	IsKindOf (const wxClassInfo *info) const
	Determines whether this class is a subclass of (or the same class as) the given class.
bool	IsSameAs (const wxObject &obj) const
	Returns true if this object has the same data pointer as obj.
void	Ref (const wxObject &clone)
	Makes this object refer to the data in clone.
void	SetRefData (wxObjectRefData *data)
	Sets the wxObject::m_refData pointer.
void	UnRef ()
	Decrements the reference count in the associated data, and if it is zero, deletes the data.
void	UnShare ()
	This is the same of AllocExclusive() but this method is public.
void	operator delete (void *buf)
	The delete operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined.
void *	operator new (size_t size, const wxString &filename=NULL, int lineNum=0)
	The new operator is defined for debugging versions of the library only, when the identifier WXDEBUG is defined.

Static Public Member Functions
static wxIdleMode	GetMode ()
	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.
static void	SetMode (wxIdleMode mode)
	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.

Additional Inherited Members
Protected Member Functions inherited from wxObject
void	AllocExclusive ()
	Ensure that this object's data is not shared with any other object.
virtual wxObjectRefData *	CreateRefData () const
	Creates a new instance of the wxObjectRefData-derived class specific to this object and returns it.
virtual wxObjectRefData *	CloneRefData (const wxObjectRefData *data) const
	Creates a new instance of the wxObjectRefData-derived class specific to this object and initializes it copying data.
Protected Attributes inherited from wxEvent
int	m_propagationLevel
	Indicates how many levels the event can propagate.

Constructor & Destructor Documentation

wxIdleEvent::wxIdleEvent

(

)

Constructor.

Member Function Documentation

static wxIdleMode wxIdleEvent::GetMode ( )

static

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 Also

SetMode().

bool wxIdleEvent::MoreRequested

(

)

const

Returns true if the OnIdle function processing this event requested more processing time.

See Also

RequestMore()

void wxIdleEvent::RequestMore

(

bool

needMore = true

)

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 forward the OnIdle event once more to the application windows.

If no window calls this function during OnIdle, then the application will remain in a passive event loop (not calling OnIdle) until a new event is posted to the application by the windowing system.

See Also

MoreRequested()

static void wxIdleEvent::SetMode ( wxIdleMode  mode )

static

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.

Parameters

mode	Can be one of the wxIdleMode values. The default is wxIDLE_PROCESS_ALL.