root/trunk/RDragDropFiles.h

// RDragDropFiles.h: interface for the RDragDropFiles class.
//
/*
    Author:         Richard Chambers, rickcham@mindspring.com

    Copyright:      Richard Chambers, 2002

    Version:        1.0

    Rights of Use:  This source code may be used by anyone for any reason
                    so long as the copyright information is maintained.

                    There is no warranty, express or implied, as to fitness
                    of purpose nor is there any other warranty, expressed
                    or implied, as to correct functioning.

                    This software depends on the existance of two functions
                    in the Windows API as well as the correct function of
                    those functions.  See the Requires section below.

    Requires:       RDragDropFiles.cpp containing the class declaration.
                    DragQueryFile function from the Windows API.
                    Client must provide a correct HDROP handle to the constructor.
                    Client must initialize file drop using DragAcceptFiles.

    Assumptions:    If debug is turned on, the macro _DEBUG is defined and ASSERT
                    is enabled.  If debug is turned off, the macro _DEBUG is
                    undefined and ASSERT is disabled.

                    The DragQueryFile Windows API function remains unchanged
                    across Windows versions (Windows 95/98/ME/NT/2000).

    Edit History:

 */

//////////////////////////////////////////////////////////////////////

#if !defined(AFX_RDRAGDROPFILES_H__D7D93FAA_AB71_4356_BF4F_884F871493D0__INCLUDED_)
#define AFX_RDRAGDROPFILES_H__D7D93FAA_AB71_4356_BF4F_884F871493D0__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

namespace rjc {
    class RDragDropFiles  
    {
    public:
        /*
            We force the user to provide an HDROP handle for the constructor.

            We overload the operator () to provide a method for checking if there
            are any more files in the list when iterating over the list using
            sNextFile.  You could also do a check on the IsEmpty method of CString
            after calling one of sFirstFile, sNextFile, or sCurrFile.

            The IsEmpty method is used to determine if there are any files in
            the file list.  It is NOT used to see if we have reached the end
            of the file list when iterating using the sNextFile method.

            The Reset method resets the file list position indicator to the
            beginning of the list.  If you do a Reset and then a sNextFile,
            you will get the first file in the list as if you had used sFirstFile.

            The Clear method is used drop the association between the object and
            the HDROP handle provided.  This means that if you use the Clear
            method, you are responsible for file drag and drop cleanup.
            You must explicitly use the DragFinish function for this cleanup
            rather than letting the RDragDropFiles object do it for you.
         */
        RDragDropFiles(HDROP hDrop);
        virtual ~RDragDropFiles();
        UINT uCount (void);
        CString & sFirstFile (CString & sBuff);
        CString & sNextFile (CString & sBuff);
        CString & sCurrFile (CString & sBuff);
        boolean operator () (void);
        boolean IsEmpty (void);
        void    Reset (void);
        void    Clear (void);

    protected:
        // we will not allow the compiler to create a
        // copy constructor or an assignment constructor.
        // Each object should be unique due to hDropFiles
        // being unique.  The destructor for the object
        // will release the drop file resources so there
        // must only be one unique object per hDropFiles.
        RDragDropFiles (RDragDropFiles &dr);
        RDragDropFiles & operator = (RDragDropFiles &dr);

    protected:
        UINT nFiles;        // number of files from hDropInfo
        UINT iPosition;     // current position in list of files
        HDROP hDropInfo;    // copy of HDROP from OnDropFiles

    };
};

#ifndef _DEBUG

//  debug versions of these are in RDragDropFiles.cpp
//  comments for these functions are also in RDragDropFiles.cpp
inline boolean rjc::RDragDropFiles::operator () () { return (hDropInfo && (iPosition < nFiles)); }
inline boolean rjc::RDragDropFiles::IsEmpty () { return (!hDropInfo || (nFiles < 1));}
inline void    rjc::RDragDropFiles::Reset () {iPosition = 0;}
inline UINT  rjc::RDragDropFiles::uCount () { return nFiles; }
inline void  rjc::RDragDropFiles::Clear () { hDropInfo = 0; nFiles = 0; }
#endif

#endif // !defined(AFX_RDRAGDROPFILES_H__D7D93FAA_AB71_4356_BF4F_884F871493D0__INCLUDED_)