如何让CEdit控件支持鼠标拖拽文本

Question

我指的不是拖拽文件，是指的拖拽文本：包括拖拽他自己里面的文本，和拖拽其它地方的文本到它里面来。

Answer 1

网上有这样的类 CDragEdit//////////////////////////////////////
//
// Author : Sam Lu
// E-mail : [email protected]
//#if !defined(AFX_CDRAGEDIT_H__871E3CD6_6359_11D1_8251_444553540000__INCLUDED_)
#define AFX_CDRAGEDIT_H__871E3CD6_6359_11D1_8251_444553540000__INCLUDED_#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
// CDragEdit.h : header file
///////////////////////////////////////////////////////////////////////////////
// CDragEdit window
#include <afxole.h>class CDragEdit;class CDEDropTarget : public COleDropTarget
{
public:
    CDEDropTarget()
        {
        ms_bBeginDrop=FALSE;
        ms_pEditCtl=NULL;
        }
    BOOL        Register(CDragEdit* pEdit);
    BOOL        OnDrop(CWnd* pWnd, COleDataObject* pDataObject, DROPEFFECT dropEffect, CPoint point);
    DROPEFFECT  OnDragEnter(CWnd* pWnd, COleDataObject* pDataObject, DWORD dwKeyState, CPoint point);
    void        OnDragLeave(CWnd* pWnd);
    DROPEFFECT  OnDragOver(CWnd* pWnd, COleDataObject* pDataObject, DWORD dwKeyState, CPoint point);
    DROPEFFECT  OnDragScroll(CWnd* pWnd, DWORD dwKeyState, CPoint point);private:
    BOOL        ms_bBeginDrop;
    CDragEdit*  ms_pEditCtl;
};class CDEDataSource : public COleDataSource
{
};#define CDragEditBase   CEditclass CDragEdit : public CDragEditBase
{
// Construction
public:
CDragEdit();// Attributes
public:
    enum {  DE_ENABLE_DRAG=1, 
            DE_ENABLE_DROP=2
    };private:
    static  BOOL    ms_bOleInit;    BOOL            ms_bDragInit;    int             ms_nEnableFlags;    BOOL            ms_bInDragging;    BOOL            ms_bDropEqualDrag;
    int             ms_nDropPtLine;
    int             ms_nDropPtPos; CDEDropTarget ms_dropTarget;
CDEDataSource ms_dropSource;// Operations
public:
    BOOL    Init(int nFlags=(DE_ENABLE_DRAG|DE_ENABLE_DROP));    BOOL    IsInDragging()                  {return ms_bInDragging;}
    void    SetDropEqualDrag(BOOL bEqual)   {ms_bDropEqualDrag=bEqual;}
    void    SetDropPos(int nLine, int nPos) {ms_nDropPtLine=nLine, 
                                             ms_nDropPtPos=nPos;}    BOOL    GetCurRange(int& nLine1, int& nPos1, int& nLine2, int& nPos2);
    BOOL    GetLinePosByCursor(int& nLine, int& nPos);    BOOL    SetCaretByCursor();
    BOOL    SetCaret(int nLine, int nPos);    BOOL    DrawCaretByCursor();    CPoint  GetPosFromLinePos(int nLine, int nPos)  
                {return PosFromChar(_LinePosToChar(nLine,nPos));}
    //we reimpelmented this function for fixing SDK's bug
    CPoint  PosFromChar(UINT uChar);    BOOL    IsInSelRange();    BOOL    EnableDrag()    
                {return (ms_nEnableFlags & DE_ENABLE_DRAG) ? TRUE : FALSE;}
    BOOL    EnableDrop()    
                {return (ms_nEnableFlags & DE_ENABLE_DROP) ? TRUE : FALSE;}
    private:
    BOOL    _GetSelText(CString& str);
    void    _CharToLinePos(int nChar, int* pnLine, int* pnPos)
                {
                if (nChar<0) nChar=0;
                *pnLine=LineFromChar(nChar);
                *pnPos=nChar-LineIndex(*pnLine);
                }
    int     _LinePosToChar(int nLine, int nPos) {return LineIndex(nLine)+nPos;}
// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CDragEdit)
//}}AFX_VIRTUAL// Implementation
public:
virtual ~CDragEdit(); // Generated message map functions
protected:
//{{AFX_MSG(CDragEdit)
afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
afx_msg BOOL OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message);
afx_msg void OnDestroy();
//}}AFX_MSG DECLARE_MESSAGE_MAP()
};///////////////////////////////////////////////////////////////////////////////{{AFX_INSERT_LOCATION}}
// Microsoft Developer Studio will insert additional declarations immediately before the previous line.#endif // !defined(AFX_CDRAGEDIT_H__871E3CD6_6359_11D1_8251_444553540000__INCLUDED_)// CDragEdit.cpp : implementation file
//
// Author : Sam Lu
// E-mail : [email protected]
//#include "stdafx.h"
#include "CDragEdit.h"#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif#define MAXLINELEN 2048enum {
    DE_INSEL, DE_BEFORESEL, DE_AFTERSEL
};/////////////////////////////////////////////////////////////////////////////
// CDragEditCDragEdit::CDragEdit()
{
    ms_bDragInit=FALSE;
    ms_nEnableFlags=0;
    ms_bInDragging=FALSE;
    ms_bDropEqualDrag=FALSE;
}CDragEdit::~CDragEdit()
{
}
BEGIN_MESSAGE_MAP(CDragEdit, CDragEditBase)
//{{AFX_MSG_MAP(CDragEdit)
ON_WM_LBUTTONDOWN()
ON_WM_SETCURSOR()
ON_WM_DESTROY()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()/////////////////////////////////////////////////////////////////////////////
// CDragEdit message handlers
BOOL CDragEdit::ms_bOleInit=FALSE;BOOL CDragEdit::Init(int nFlags) 
{
    if (!ms_bOleInit) {
 //       if (!AfxOleInit()) {
 //           TRACE("Fail in OLE initialating\n");
 //           return FALSE;
 //       }
        ms_bOleInit=TRUE;
    }    if (ms_bDragInit) return FALSE;    ms_nEnableFlags=nFlags;    if (!GetSafeHwnd()) {
        TRACE("You should create CDragEdit first, before this function is called\n");
return FALSE;
    }
if (!ms_dropTarget.Register(this)) {
TRACE("Fail in registing drop target\n");
return FALSE;
}
    ms_bDragInit=TRUE;
return TRUE;
}//we reimpelmented this function for fixing SDK's bug that
//it always returns (-1,-1) when the uChar is the last char
CPoint CDragEdit::PosFromChar(UINT uChar)
{
    if (0==uChar)
        return CPoint(0,0);
    CPoint pt=CDragEditBase::PosFromChar(uChar);
    if (pt.x<0 && pt.y<0) {
        int nLine, nPos;
        _CharToLinePos((int)uChar,&nLine,&nPos);
        //get dc and select current using font
        CClientDC dc(this);
        dc.SelectObject(GetFont());
        //get position of previous char
        pt=CDragEditBase::PosFromChar(uChar-1);        
        if (nPos==0) {
            //if current char is the first char
            //we get the current y from previous y plus font height
            CSize szFont=dc.GetTextExtent("A",1);
            pt.y+=szFont.cy;
            pt.x=0;
        }
        else {
            char szBuf[MAXLINELEN];
            GetLine(nLine,szBuf,sizeof(szBuf));
            CSize szFont=dc.GetTextExtent(&szBuf[nPos-1],1);
            pt.x+=szFont.cx;
        }
        dc.SelectStockObject(SYSTEM_FONT);
    }
    return pt;
}

Answer 2

//get line and pos information from current selection range
BOOL CDragEdit::GetCurRange(int& nLine1, int& nPos1, int& nLine2, int& nPos2)
{
    //get current selection range
    GetSel(nPos1,nPos2);
    //and trans. to line, pos
    _CharToLinePos(nPos1,&nLine1,&nPos1);
    _CharToLinePos(nPos2,&nLine2,&nPos2);
    return TRUE;
}//get line and pos from current cursor position
//return TRUE, if cursor is exactly at a char
//return FALSE, if cursor is at white space area
BOOL CDragEdit::GetLinePosByCursor(int& nLine, int& nPos)
{
    CPoint ptCursor;
    GetCursorPos(&ptCursor);
    ScreenToClient(&ptCursor);    nPos=(int)(short)LOWORD((DWORD)CharFromPos(ptCursor));
    if (nPos<0) nPos=0;
    _CharToLinePos(nPos,&nLine,&nPos);    //the following codes will check if cusor is at white space area
    //get the maximum x of nLine
    CPoint ptChar;
    ptChar=PosFromChar(LineIndex(nLine)+LineLength(LineIndex(nLine)));
    if (ptChar.x<ptCursor.x || ptCursor.x<0)
        return FALSE;
    return TRUE;
}//set edit's caret position by current cursor position
BOOL CDragEdit::SetCaretByCursor()
{
    //get cursor's position and translate it to client coordinate
    CPoint ptCursor;
    GetCursorPos(&ptCursor);
    ScreenToClient(&ptCursor);
    //set caret position
    int nChar=(int)LOWORD((DWORD)CharFromPos(ptCursor));
    SetSel(nChar,nChar);
    return TRUE;
}BOOL CDragEdit::SetCaret(int nLine, int nPos)
{
    int nChar=_LinePosToChar(nLine,nPos);
    SetSel(nChar,nChar);
    return TRUE;
}//draw a caret at current cursor position
//this function will not affect the caret position or selection status
BOOL CDragEdit::DrawCaretByCursor()
{
    int nLine, nPos;
    GetLinePosByCursor(nLine,nPos);
    SetCaretPos(GetPosFromLinePos(nLine,nPos));
    return TRUE;
}//test if (nLine,Pos) is within (nLine1,nPos1)~(nLine2,nPos2)
static int LinePosInRange(int nLine, int nPos,
                           int nLine1, int nPos1,
                           int nLine2, int nPos2)
{
    if (nLine1==nLine2) {//single line selection 
        if (nLine<nLine1) return DE_BEFORESEL;
        if (nLine>nLine1) return DE_AFTERSEL;
        //nLine==nLine1
        if (nPos<nPos1) return DE_BEFORESEL;
        if (nPos>nPos2) return DE_AFTERSEL;
    }
    else { //multi-line selection 
        if (nLine<nLine1) return DE_BEFORESEL;
        if (nLine>nLine2) return DE_AFTERSEL;
        if (nLine==nLine1 && 
            nPos<nPos1) return DE_BEFORESEL;
        if (nLine==nLine2 && 
            nPos>nPos2) return DE_AFTERSEL;
    }
    return DE_INSEL;
}//return TRUE, if cursor is within the selection 
BOOL CDragEdit::IsInSelRange()
{
    int nLine1, nPos1, nLine2, nPos2;
    GetCurRange(nLine1,nPos1,nLine2,nPos2);
    if (nLine1==nLine2 && nPos1==nPos2) //no selection 
        return FALSE;    int nLine, nPos;
    if (!GetLinePosByCursor(nLine,nPos)) //out of selection 
        return FALSE;
    return (LinePosInRange(nLine,nPos,nLine1,nPos1,
                           nLine2,nPos2)==DE_INSEL) ? TRUE : FALSE;
}BOOL CDragEdit::_GetSelText(CString& str)
{
    int nLine1, nPos1, nLine2, nPos2;
    GetCurRange(nLine1,nPos1,nLine2,nPos2);
    ASSERT(nLine1>=0 && nPos1>=0 && nLine2>=0 && nPos2>=0);
    char szBuf[MAXLINELEN];
    int nLen;
    //single-line selection
    if (nLine1==nLine2) {
        nLen=GetLine(nLine1,szBuf,sizeof(szBuf));
        szBuf[nLen]='\0';
        szBuf[nPos2]='\0';
        str=szBuf+nPos1;
        return TRUE;
    }
    //multi-line section
    nLen=GetLine(nLine1,szBuf,sizeof(szBuf));
    szBuf[nLen]='\0';
    str=szBuf+nPos1;
    for (int i=nLine1+1; i<nLine2; i++) {
        str+="\r\n";
        nLen=GetLine(i,szBuf,sizeof(szBuf));
        szBuf[nLen]='\0';
        str+=szBuf;
    }
    str+="\r\n";
    nLen=GetLine(nLine2,szBuf,sizeof(szBuf));
    szBuf[nLen]='\0';
    szBuf[nPos2]='\0';
    str+=szBuf;
    return TRUE;
}void CDragEdit::OnLButtonDown(UINT nFlags, CPoint point) 
{
    if (!EnableDrag()) {
        CDragEditBase::OnLButtonDown(nFlags, point);
        return;
    }    if (IsInSelRange()) {
        //get selected text
        CString str;
        if (!_GetSelText(str)) {
            CDragEditBase::OnLButtonDown(nFlags, point);
            return;
        }
        int nLine1, nPos1, nLine2, nPos2;
        GetCurRange(nLine1,nPos1,nLine2,nPos2);
        //make a copy of selected text to a global memory
        HGLOBAL hData=GlobalAlloc(GHND|GMEM_SHARE,strlen(str)+1);
        strcpy((LPSTR)GlobalLock(hData),str);
        GlobalUnlock(hData);
        ms_dropSource.CacheGlobalData(CF_TEXT,hData);        //defined dragging area
        CRect   rc(point.x-5, point.y-5, point.x+5, point.y+5);
        //It seems it is a MFC's bug that MFC will set capture to AfxGetMainWnd()
        //and use its coordinate to test the lpRectStartDrag.
        //So, we need to first translate the rc's coordinate.
        MapWindowPoints(AfxGetMainWnd(),&rc);        //start dragging
        ms_bDropEqualDrag=FALSE;
        ms_bInDragging=TRUE;
        DROPEFFECT dwEffect=ms_dropSource.DoDragDrop(DROPEFFECT_COPY|DROPEFFECT_MOVE,&rc);
        ms_bInDragging=FALSE;
        if (dwEffect & (DROPEFFECT_MOVE | DROPEFFECT_COPY)) {
            if (dwEffect & DROPEFFECT_MOVE) {
                if (ms_bDropEqualDrag) {
                    //If drag source equal to drop target and user want to
                    //move string
                    ms_bDropEqualDrag=FALSE;
                    int nSel=LinePosInRange(ms_nDropPtLine,ms_nDropPtPos,
                                             nLine1,nPos1,nLine2,nPos2);
                    //we don't allow the string be moved into selection area
                    if (nSel==DE_INSEL)
                        return;
                    else {
                        if (nSel==DE_AFTERSEL) {
                            //If user want to move the string back,
                            //we need to adjust the ms_nDropPtLine 
                            //and ms_nDropPtPos
                            int nChar=_LinePosToChar(ms_nDropPtLine,ms_nDropPtPos);
                            nChar-=str.GetLength();
                            //delet selected string first
                            ReplaceSel("",TRUE);
                            _CharToLinePos(nChar,&ms_nDropPtLine,&ms_nDropPtPos);
                            //set new insert point
                            SetCaret(ms_nDropPtLine,ms_nDropPtPos);
                        }
                        else {
                            //delet selected string first
                            ReplaceSel("",TRUE);
                            //set new insert point
                            SetCaret(ms_nDropPtLine,ms_nDropPtPos);
                        }
                        //insert dragged string and sel. it
                        int nBeg, nEnd;
                        GetSel(nBeg,nEnd);        
                        nEnd+=str.GetLength();
                        ReplaceSel(str,TRUE);
                        SetSel(nBeg,nEnd);
                    }
                }
                else
                    ReplaceSel("",TRUE);
            }
            ms_bDropEqualDrag=FALSE;
            return;
        }
        ms_bDropEqualDrag=FALSE;
        //If user does not want to drag string, we reset the caret pos.
    SetCaretByCursor();
        return;
    }
CDragEditBase::OnLButtonDown(nFlags, point);
}

Answer 3

BOOL CDragEdit::OnSetCursor(CWnd* pWnd, UINT nHitTest, UINT message) 
{
    if (EnableDrag()) {
        if (IsInSelRange()) {
            //if the cursor is over a selection 
            //we will change the cursor shape to a arrow type
            //It means user can drag it.
            ::SetCursor(AfxGetApp()->LoadStandardCursor(IDC_ARROW));
            return FALSE;
        }        
    }
    //Otherwise, we keep the cursor shape as its original type
return CDragEditBase::OnSetCursor(pWnd, nHitTest, message);
}
void CDragEdit::OnDestroy()
{
if(ms_bDragInit)
ms_dropTarget.Revoke();
CDragEditBase::OnDestroy();
}/*************************************************************
CDEDropTarget
**************************************************************/
BOOL CDEDropTarget::Register(CDragEdit* pEdit)
{
    ms_pEditCtl=pEdit;
    return COleDropTarget::Register(pEdit);
}DROPEFFECT CDEDropTarget::OnDragScroll(CWnd* pWnd, DWORD dwKeyState, CPoint point)
{
    ASSERT(ms_pEditCtl);
TRACE0("....DragScroll....\n");    //if pWnd is kind of CView, we let COleDropTarget to handle it
if (pWnd->IsKindOf(RUNTIME_CLASS(CView)))
return COleDropTarget::OnDragScroll(pWnd,dwKeyState,point);
TRACE0("....DragScroll(1)....\n");    if (!ms_bBeginDrop)
        return DROPEFFECT_NONE; TRACE0("....DragScroll(2)....\n");
    CRect rectClient;
ms_pEditCtl->GetClientRect(&rectClient);
CRect rect = rectClient;
    //nScrollInset is a COleDropTarget's static member variable
    rect.InflateRect(-nScrollInset, /*-nScrollInset*/0);
// hit-test against inset region
if (rectClient.PtInRect(point) && !rect.PtInRect(point)) {
        UINT        uMsg;
        int         nCode;
        CScrollBar* pScrollBar=NULL;        
// determine which way to scroll along both X & Y axis
        if (point.x<rect.left) {
            pScrollBar=ms_pEditCtl->GetScrollBarCtrl(SB_HORZ);
            uMsg=WM_HSCROLL;
nCode=SB_LINELEFT;
        }
        else if (point.x>=rect.right) {
            pScrollBar=ms_pEditCtl->GetScrollBarCtrl(SB_HORZ);
            uMsg=WM_HSCROLL;
nCode=SB_LINERIGHT;
        }
        if (point.y<rect.top) {
            pScrollBar=ms_pEditCtl->GetScrollBarCtrl(SB_VERT);
            uMsg=WM_VSCROLL;
nCode=SB_LINEUP;
        }
        else if (point.y>=rect.bottom) {
pScrollBar=ms_pEditCtl->GetScrollBarCtrl(SB_VERT);
            uMsg=WM_VSCROLL;
nCode=SB_LINEDOWN;
        }        LRESULT l=ms_pEditCtl->SendMessage(uMsg,MAKEWPARAM(nCode,0),
            (LPARAM)(pScrollBar ? pScrollBar->GetSafeHwnd() : NULL));        ms_pEditCtl->DrawCaretByCursor(); TRACE0("....DragScroll(10)....\n");
        if (dwKeyState & MK_CONTROL)
            return DROPEFFECT_SCROLL | DROPEFFECT_COPY;
        else
            return DROPEFFECT_SCROLL | DROPEFFECT_MOVE;
    }
TRACE0("....DragScroll(11)....\n");
    return DROPEFFECT_NONE;
}DROPEFFECT CDEDropTarget::OnDragEnter(CWnd* pWnd, COleDataObject* pDataObject, 
                                      DWORD dwKeyState, CPoint point)
{
TRACE0("Start Dragging(0)....\n");
    ASSERT(ms_pEditCtl);    if (!ms_pEditCtl->EnableDrop() || 
        !pDataObject->IsDataAvailable(CF_TEXT))
        return DROPEFFECT_NONE;    DROPEFFECT dwEffect;
    
    if (dwKeyState & MK_CONTROL)
        dwEffect=DROPEFFECT_COPY;
    else
        dwEffect=DROPEFFECT_MOVE;    ms_bBeginDrop=TRUE;    //we set focus to current window such that the caret will be shown
    ms_pEditCtl->SetFocus(); TRACE0("Start Dragging(1)....\n");
    return dwEffect;
}void CDEDropTarget::OnDragLeave(CWnd* pWnd)
{
    ASSERT(ms_pEditCtl); TRACE0("Leaved....\n");
    ms_bBeginDrop=FALSE;
}DROPEFFECT CDEDropTarget::OnDragOver(CWnd* pWnd, COleDataObject* pDataObject, 
                                     DWORD dwKeyState, CPoint point)
{
    ASSERT(ms_pEditCtl);
TRACE0(" .... Dragging(1)....\n");    if (!ms_bBeginDrop)
        return DROPEFFECT_NONE;    DROPEFFECT dwEffect;
    
    if (dwKeyState & MK_CONTROL)
        dwEffect=DROPEFFECT_COPY;
    else
        dwEffect=DROPEFFECT_MOVE;    ms_pEditCtl->DrawCaretByCursor();
TRACE0(" .... Dragging(2)....\n");
    return dwEffect;
}BOOL CDEDropTarget::OnDrop(CWnd* pWnd, COleDataObject* pDataObject,
                           DROPEFFECT dropEffect, CPoint point)
{
    ASSERT(ms_pEditCtl); TRACE0("Dropped....\n");
    if (!ms_bBeginDrop)
        return FALSE;    if (ms_pEditCtl->IsInDragging() &&
        ms_pEditCtl->IsInSelRange())
        return DROPEFFECT_NONE;    HGLOBAL hData=pDataObject->GetGlobalData(CF_TEXT);
    if (!hData) {
        TRACE("Fail in getting data\n");
        return FALSE;
    }
    LPCSTR lpcszData=(LPCSTR)GlobalLock(hData);
    if ((dropEffect & DROPEFFECT_MOVE) &&
        ms_pEditCtl->IsInDragging()) {
        //If the drag window equal to drop window and
        //user want to move string, we let drag source
        //to move string by itself
        ms_pEditCtl->SetDropEqualDrag(TRUE);
        int nLine, nPos;
        ms_pEditCtl->GetLinePosByCursor(nLine,nPos);
        ms_pEditCtl->SetDropPos(nLine,nPos);
    }
    else {
        //set dropped point
        ms_pEditCtl->SetCaretByCursor();
        //insert string and select the inserted string
        int nBeg, nEnd;
        ms_pEditCtl->GetSel(nBeg,nEnd);        
        nEnd+=strlen(lpcszData);
        ms_pEditCtl->ReplaceSel(lpcszData,TRUE);
        ms_pEditCtl->SetSel(nBeg,nEnd);
    }
    GlobalUnlock(hData);
    return TRUE;
}