把其它程序(如網頁等)的文字拖放到Memo裏

 

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　　原作者：Victor Chen 來　源：C++ 愛好者 網址: http://www.cppfans.com/ Email: victor@cppfans.com 需要用 COM 接口的 OLE 拖放目標, 程序新建一個支持拖放目標的UnitTMyDropTarget 單元, 在這個單元裏創建一個 TMyDropTarget 類。 這個程序可以使從寫字板或者網頁等定義的文本塊用鼠標拖動, 放到程序的 Memo 裏, 插入到 Memo 的拖放的位置。 首先看看如何使用這個 TMyDropTarget 類: 在 Form 的頭文件裏 (例如 Unit1.h) 需要增加的內容(藍色部分是新增內容): #include "UnitTMyDropTarget.h" class TForm1 : public TForm { private: // User declarations TMyDropTarget *DropMemo1; //自定義的拖放目標類 void __fastcall DropMemo1Text(IDropTarget *Sender, AnsiString AText, DWord KeyState, TPoint pt); //拖放事件 public: // User declarations __fastcall TForm1(TComponent* Owner); __fastcall ~TForm1(); }; 在 From 的 .cpp 文件裏 (例如 Unit1.cpp), 需要增加的內容(藍色部分是新增內容): __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) { OleInitialize(NULL); DropMemo1 = new TMyDropTarget(Memo1); DropMemo1->OnProcessText = DropMemo1Text; } //--------------------------------------------------------------------------- __fastcall TForm1::~TForm1() { DropMemo1->Release();//delete DropMemo1; OleUninitialize(); } //--------------------------------------------------------------------------- void __fastcall TForm1::DropMemo1Text(IDropTarget *Sender, AnsiString AText, DWORD KeyState, TPoint pt) { POINTS p={pt.x,pt.y}; *(long*)&p=SendMessage(Memo1->Handle,EM_CHARFROMPOS,0,*(long*)&p); Memo1->SelStart = p.x; Memo1->SelLength = 0; Memo1->SelText = AText; } //--------------------------------------------------------------------------- TMyDropTarget 類的實現: 頭文件 UnitTMyDropTarget.h 的內容: //--------------------------------------------------------------------------- #ifndef UnitTMyDropTargetH #define UnitTMyDropTargetH //--------------------------------------------------------------------------- #include "oleidl.h" #include "controls.hpp" //--------------------------------------------------------------------------- class TMyDropTarget: public IDropTarget { public: __property void __fastcall (__closure *OnGetFormat)(IDropTarget *Sender, IDataObject *DataObject, DWORD KeyState, TPoint pt, DWORD &dpe, bool &bDataOK) = { read=_FGetFormat, write=_FGetFormat }; __property void __fastcall (__closure *OnProcessData)(IDropTarget *Sender, IDataObject *DataObject, DWORD KeyState, TPoint pt) = { read=_FProcessData, write=_FProcessData }; __property void __fastcall (__closure *OnProcessText)(IDropTarget *Sender, AnsiString AText, DWORD KeyState, TPoint pt) = { read=_FProcessText, write=_FProcessText }; TMyDropTarget(TWinControl *AOwner); ~TMyDropTarget(); HRESULT __stdcall QueryInterface(const GUID &iid, void **ppv); ULONG __stdcall AddRef(void) { return ++_iRefCount; } ULONG __stdcall Release(void) { if(--_iRefCount==0){delete this;} return _iRefCount; } HRESULT __stdcall DragEnter(IDataObject *pDataObject, DWORD grfKeyState, POINTL pt, DWORD *pdwEffect); HRESULT __stdcall DragOver(DWORD grfKeyState, POINTL pt, DWORD *pdwEffect); HRESULT __stdcall DragLeave(void); HRESULT __stdcall Drop(IDataObject *pDataObject, DWORD grfKeyState, POINTL pt, DWORD * pdwEffect); private: ULONG _iRefCount; IDataObject *_lpDataObj; TWinControl *_OwnerControl; void __fastcall (__closure *_FGetFormat)(IDropTarget *Sender, IDataObject *DataObject, DWORD KeyState, TPoint pt, DWORD &dpe, bool &bDataOK); void __fastcall (__closure *_FProcessData)(IDropTarget *Sender, IDataObject *DataObject, DWORD KeyState, TPoint pt); void __fastcall (__closure *_FProcessText)(IDropTarget *Sender, AnsiString AText, DWORD KeyState, TPoint pt); bool __fastcall FDataFormatOK(DWORD KeyState, POINTL pt, DWORD &dpe); void __fastcall FProcessData(DWORD KeyState, POINTL pt); }; //--------------------------------------------------------------------------- #endif //--------------------------------------------------------------------------- UnitTMyDropTarget.cpp 的內容: //--------------------------------------------------------------------------- #include "UnitTMyDropTarget.h" //--------------------------------------------------------------------------- TMyDropTarget::TMyDropTarget(TWinControl *AOwner) { _OwnerControl = AOwner; _iRefCount = 0; _lpDataObj = NULL; _FGetFormat = NULL; _FProcessData = NULL; _FProcessText = NULL; RegisterDragDrop(_OwnerControl->Handle,this); } //--------------------------------------------------------------------------- TMyDropTarget::~TMyDropTarget() { RevokeDragDrop(_OwnerControl->Handle); } //--------------------------------------------------------------------------- HRESULT __stdcall TMyDropTarget::QueryInterface(const GUID &iid, void **ppv) { if((iid==IID_IUnknown)(iid==IID_IDropTarget)) { *ppv=this; AddRef(); } else { *ppv=NULL; return E_NOINTERFACE; } return S_OK; } //--------------------------------------------------------------------------- HRESULT __stdcall TMyDropTarget::DragEnter(IDataObject *pDataObject, DWORD grfKeyState, POINTL pt, DWORD *pdwEffect) { _lpDataObj = pDataObject; FDataFormatOK(grfKeyState,pt,*pdwEffect); return S_OK; } //--------------------------------------------------------------------------- HRESULT __stdcall TMyDropTarget::DragOver(DWORD grfKeyState, POINTL pt, DWORD *pdwEffect) { FDataFormatOK(grfKeyState,pt,*pdwEffect); return S_OK; } //--------------------------------------------------------------------------- HRESULT __stdcall TMyDropTarget::DragLeave(void) { &n