GDragAndDrop.h

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#ifndef __DRAG_AND_DROP
#define __DRAG_AND_DROP

#include "GVariant.h"

#if defined WIN32

#include <shlobj.h>
#include "GCom.h"

#else

#define S_OK                                0
#define DROPEFFECT_NONE                     0x0
#define DROPEFFECT_COPY                     0x1
#define DROPEFFECT_MOVE                     0x2
#define DROPEFFECT_LINK                     0x4

#endif

// int <-> char* format conversions
#if defined WIN32

#endif

class LgiClass GDragDropSource
#if defined WIN32
    : public IDropSource, public IEnumFORMATETC
#elif defined XWIN
    : public QObject
#endif
{
    friend class GDataObject;

protected:
    char *CurrentFormat;
    
    #if defined WIN32
    int Index;

    // IUnknown
    ULONG STDMETHODCALLTYPE AddRef();
    ULONG STDMETHODCALLTYPE Release();
    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, void **ppv);

    // IEnumFORMATETC
    HRESULT STDMETHODCALLTYPE Next(ULONG celt, FORMATETC *rgelt, ULONG *pceltFetched);
    HRESULT STDMETHODCALLTYPE Skip(ULONG celt);
    HRESULT STDMETHODCALLTYPE Reset();
    HRESULT STDMETHODCALLTYPE Clone(IEnumFORMATETC **ppenum);

    // IDropSource
    HRESULT STDMETHODCALLTYPE QueryContinueDrag(BOOL fEscapePressed, DWORD InputState);
    HRESULT STDMETHODCALLTYPE GiveFeedback(DWORD dwEffect);
    #endif

    bool CreateFileDrop(GVariant *Var, GMouse &m, List<char> &Files);

    #ifdef XWIN
    void OnSelectionRequest(Display *Dsp, XEvent &Event, QWidget *W, Atom XdndSelection); 
    #endif
    
public:
    GDragDropSource();
    ~GDragDropSource();

    int Drag(GView *SourceWnd, int Effect);

    virtual void OnRegister(bool Success) {}
    virtual void OnStartData() {}
    virtual void OnEndData() {}
    
    virtual bool GetData(GVariant *Data,        // out
                         char *Format           // in
                         ) { return false; }

    virtual bool GetFormats(List<char> &Formats) { return false; }
};

class LgiClass GDragDropTarget
#if defined WIN32
    : public IDropTarget
#elif defined XWIN
    : public QObject
#endif
{
private:
    GView *To;
    uchar *DragDropData;
    int DragDropLength;
    List<char> Formats;

    #if defined WIN32
    // IUnknown
    ULONG STDMETHODCALLTYPE AddRef();
    ULONG STDMETHODCALLTYPE Release();
    HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, void **ppv);

    // IDropTarget
    HRESULT STDMETHODCALLTYPE DragEnter(IDataObject *pDataObject, DWORD grfKeyState, POINTL pt, DWORD *pdwEffect);
    HRESULT STDMETHODCALLTYPE DragOver(DWORD grfKeyState, POINTL pt, DWORD *pdwEffect);
    HRESULT STDMETHODCALLTYPE DragLeave(void);
    HRESULT STDMETHODCALLTYPE Drop(IDataObject *pDataObject, DWORD grfKeyState, POINTL pt, DWORD *pdwEffect);

    #endif

protected:
    #if defined WIN32
    // Data elements
    IDataObject *DataObject;

    // Tools
    bool OnDropFileGroupDescriptor(FILEGROUPDESCRIPTOR *Data, GArray<char*> &Files);
    #endif

public:
    GDragDropTarget();
    ~GDragDropTarget();

    // call this when you have a HWND
    void SetWindow(GView *To);

    // Override these

    // Events
    virtual void OnDragInit(bool Success) {}
    virtual void OnDragEnter() {}
    virtual void OnDragExit() {}

    // 'WillAccept' is called to see whether this target
    // can cope with any of the data types being passed to it.
    // Once you have decided what format you want the data in
    // clear all the other formats from the list. The first
    // format left in the list will be passed to the 'OnDrop'
    // function.
    virtual int WillAccept(List<char> &Formats, GdcPt2 Pt, int KeyState) { return DROPEFFECT_NONE; }

    // 'OnDrop' is called when the user releases the data over
    // your window. The data is going to be a binary GVariant
    // in the format you accepted earlier.
    virtual int OnDrop(char *Format, GVariant *Data, GdcPt2 Pt, int KeyState) { return DROPEFFECT_NONE; }
};

#endif

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