IObjectDrag.h

//----------------------------------------------------------------------
// Interface:   IObjectDrag
// Authors: Liu Weili
// Date:    2006.4.5
// Revised: by LiXizhi 2007.11.4
// desc: 
// This interface is intended to provide a common interface for all objects
// which are intended to be dragged in some way. 
// We don't need to know the actual type of the objects through this interface.
//-----------------------------------------------------------------------

#pragma once
#include <string>
namespace ParaEngine
{
    using std::vector;
    class IObjectDrag;
    struct CGUIPosition;
    /*
    This is a structure for drag-and-drop operation.
    It stores necessary information for a dragging operation.
    */
    struct STRUCT_DRAG_AND_DROP {
        IObjectDrag* pSource;           //where the drag begin, the dragging object's parent
        IObjectDrag* pDestination;      //where to drop
        IObjectDrag* pDragging;     //the dragging object which moves with the mouse cursor

        int nEvent;         //which event triggers the dragging. If mouse,that is which button is pressed.
        int startX, startY; // the absolute screen position when the drag start. 
        int nRelativeX,nRelativeY,nRelativeZ;//relative position of the dragging control's top-left point with respect to  
        // this is used to restore an UI object to its original position. 
        CGUIPosition*       m_pOldPosition;
        // if true, the pDragging is only a dragging candidates and is expect to receive all mouse event if the button is down.
        bool m_bIsCandicateOnly;
        //the mouse position when it starts dragging.
        void (*pCleanUp)();         //call back function when dragging is over in order to do clean up jobs 
        //such as deleting the dragging object or change state of other objects.
        void init();

    public:
        void SetOldPosition(const CGUIPosition& vPos);

        CGUIPosition* GetOldPosition();

        void CleanUpReceivers();

        void AddReceiver(const char* sName);

        bool HasReceiver(const char* sName);

        void SetDraggingCandidate(IObjectDrag* pDragging);
        void UnsetDraggingCandidate();
    private:
        vector <string> m_receiverNames;
    };

    class IObjectDrag
    {
    public:
        IObjectDrag():m_bCandrag(false) {};
        virtual void SetCandrag(bool bCandrag)=0;
        virtual bool GetCandrag()const=0;
        virtual void BeginDrag(int nEvent, int x, int y, int z)=0;
        virtual void EndDrag(int nEvent, int x, int y, int z)=0;
        virtual BOOL IsOnObject(int x,int y, int z)=0;

        virtual void SetPositionI(const CGUIPosition& position){};

        static STRUCT_DRAG_AND_DROP DraggingObject;

        static bool CancelDrag(STRUCT_DRAG_AND_DROP* pdrag);
    protected:
        bool        m_bCandrag;
    };
}