TQCustomEvent Class Reference

The TQCustomEvent class provides support for custom events. More...

#include <ntqevent.h>

Inherits TQEvent.

List of all member functions.

Public Members

TQCustomEvent ( int type )
TQCustomEvent ( Type type, void * data )
void * data () const
void setData ( void * data )

Detailed Description

The TQCustomEvent class provides support for custom events.

TQCustomEvent is a generic event class for user-defined events. User defined events can be sent to widgets or other TQObject instances using TQApplication::postEvent() or TQApplication::sendEvent(). Subclasses of TQObject can easily receive custom events by implementing the TQObject::customEvent() event handler function.

TQCustomEvent objects should be created with a type ID that uniquely identifies the event type. To avoid clashes with the TQt-defined events types, the value should be at least as large as the value of the "User" entry in the TQEvent::Type enum.

TQCustomEvent contains a generic void* data member that may be used for transferring event-specific data to the receiver. Note that since events are normally delivered asynchronously, the data pointer, if used, must remain valid until the event has been received and processed.

TQCustomEvent can be used as-is for simple user-defined event types, but normally you will want to make a subclass of it for your event types. In a subclass, you can add data members that are suitable for your event type.

Example:

    class ColorChangeEvent : public TQCustomEvent
    {
    public:
        ColorChangeEvent( TQColor color )
            : TQCustomEvent( 65432 ), c( color ) {}
        TQColor color() const { return c; }
    private:
        TQColor c;
    };

    // To send an event of this custom event type:

    ColorChangeEvent* ce = new ColorChangeEvent( blue );
    TQApplication::postEvent( receiver, ce );  // TQt will delete it when done

    // To receive an event of this custom event type:

    void MyWidget::customEvent( TQCustomEvent * e )
    {
        if ( e->type() == 65432 ) {  // It must be a ColorChangeEvent
            ColorChangeEvent* ce = (ColorChangeEvent*)e;
            newColor = ce->color();
        }
    }

Member Function Documentation

TQCustomEvent::TQCustomEvent ( int type )

Constructs a custom event object with event type type. The value of type must be at least as large as TQEvent::User. The data pointer is set to 0.

TQCustomEvent::TQCustomEvent ( Type type, void * data )

Constructs a custom event object with the event type type and a pointer to data. (Note that any int value may safely be cast to TQEvent::Type).

void * TQCustomEvent::data () const

Returns a pointer to the generic event data.

void TQCustomEvent::setData ( void * data )

Sets the generic data pointer to data.