wxPaintEvent Class Reference

#include <wx/event.h>

Inheritance diagram for wxPaintEvent:

Detailed Description

A paint event is sent when a window's contents needs to be repainted.

The handler of this event must create a wxPaintDC object and use it for painting the window contents. For example:

void MyWindow::OnPaint(wxPaintEvent& event)
{
    wxPaintDC dc(this);

    DrawMyDocument(dc);
}

Notice that you must not create other kinds of wxDC (e.g. wxClientDC or wxWindowDC) in EVT_PAINT handlers and also don't create wxPaintDC outside of this event handlers.

You can optimize painting by retrieving the rectangles that have been damaged and only repainting these. The rectangles are in terms of the client area, and are unscrolled, so you will need to do some calculations using the current view position to obtain logical, scrolled units. Here is an example of using the wxRegionIterator class:

// Called when window needs to be repainted.
void MyWindow::OnPaint(wxPaintEvent& event)
{
    wxPaintDC dc(this);

    // Find Out where the window is scrolled to
    int vbX,vbY;                     // Top left corner of client
    GetViewStart(&vbX,&vbY);

    int vX,vY,vW,vH;                 // Dimensions of client area in pixels
    wxRegionIterator upd(GetUpdateRegion()); // get the update rect list

    while (upd)
    {
        vX = upd.GetX();
        vY = upd.GetY();
        vW = upd.GetW();
        vH = upd.GetH();

        // Alternatively we can do this:
        // wxRect rect(upd.GetRect());

        // Repaint this rectangle
        ...some code...

        upd ++ ;
    }
}

Remarks

Please notice that in general it is impossible to change the drawing of a standard control (such as wxButton) and so you shouldn't attempt to handle paint events for them as even if it might work on some platforms, this is inherently not portable and won't work everywhere.

Events using this class

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

void handlerFuncName(wxPaintEvent& event)

Event macros:

• EVT_PAINT(func):
  Process a wxEVT_PAINT event.

Library:  wxCore

Category:  Events

See Also

Events and Event Handling

Public Member Functions
	wxPaintEvent (int id=0)
	Constructor.
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.

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

wxPaintEvent::wxPaintEvent

(

int

id = 0

)

Constructor.