gxeventhandler.h

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//
// Copyright (C) 2017 Graeme Walker
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
// ===
///
/// \file gxeventhandler.h
///

#ifndef GX_EVENT_HANDLER_H
#define GX_EVENT_HANDLER_H

#include "gdef.h"
#include "gxdef.h"

namespace GX
{
    class EventHandler ;
}

/// \class GX::EventHandler
/// An interface for delivering GX::EventLoop events, with do-nothing default method implementations.
/// 
/// One Xlib event can trigger several different callbacks methods at this interface in order to 
/// resemble other windowing systems.
/// 
class GX::EventHandler
{
public:
    virtual ~EventHandler() ;
        ///< Destructor.

    virtual bool onIdle() ;
        ///< Called by GX::Application::run() once the event queue is empty.
        ///< Returns false when idle work is complete.

    virtual void onLeftMouseButtonDown( int x , int y , bool shift , bool control ) ;
        ///< Called for a left-mouse-button-down event.

    virtual void onLeftMouseButtonUp( int x , int y , bool shift , bool control ) ;
        ///< Called for a left-mouse-button-up event.

    virtual void onMouseMove( int x , int y ) ;
        ///< Called for a mouse-move event.

    virtual void onExposure( int x , int y , int dx , int dy ) ;
        ///< Called first for a window-expose event.

    virtual void onPaint() ;
        ///< Called second for a window-expose event.

    virtual void onExpose( ::XExposeEvent & ) ;
        ///< Called third for a window-expose event.

    virtual bool onCreate() ;
        ///< Called first for a window-map event. Returns false to abort
        ///< window creation.

    virtual void onShow() ;
        ///< Called second for a window-map event.

    virtual void onMap( ::XMapEvent & ) ;
        ///< Called third for a window-map event.

    virtual void onKeyPress( ::XKeyEvent & ) ;
        ///< Called for a key-press event.

    virtual void onKeyRelease( ::XKeyEvent & ) ;
        ///< Called for a key-release event.

    virtual void onUser() ;
        ///< Called for a client-message event.

private:
    void operator=( const EventHandler & ) ;
} ;

#endif