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Posted 17 Nov 2003

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Drag and Drop in a Dialog

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4.79/5 (38 votes)
6 Dec 2012CPOL1 min read
Simple Drag and Drop functionality in a dialog.

Introduction

Here is a simple method to have a Drag and Drop feature in your dialog based applications. To provide Drag and Drop we have a Windows Message Handler called WM_DROPFILES. Handle this message through the ON_MESSAGE message map to capture the dropped files.

Message Handler

C++
//
 BEGIN_MESSAGE_MAP(CComGuidFinderDlg, CDialog)
  //{{AFX_MSG_MAP(CComGuidFinderDlg)
  ON_WM_PAINT()
  ON_WM_LBUTTONDOWN()
  ON_MESSAGE(WM_DROPFILES,OnDropFiles)// Message Handler for Drang and Drop
  //}}AFX_MSG_MAP
END_MESSAGE_MAP()
//

Now it is time to handle the WM_DROPFILES messages through a user defined method. The function prototype should be like this:

C++
LRESULT  OnDropFiles(WPARAM wParam,LPARAM lParam);

Finally we have a function to capture the drop events. wParam is a handle to the HDROP structure describing the dropped files. To get info about the dropped file, i.e., the file name used:

C++
DragQueryFile(hDrop,    // Struture Identifier
        -1,        // -1 to Drop more than one file or ( integer 0 to max )
                   // to drop selected No of files
        szDroppedFile,// Droped File Name
        MAX_PATH);   // Max char

So now we have done all possible coding in our dialog based application to handle the Drag & Drop feature. But still it is handicapped. Handling the Drop event is not enough to ensure the Drag & Drop feature. We need to register our window to accept the dropped file using:

C++
BOOL CComGuidFinderDlg::OnInitDialog()
{
  ......
  .....
  DragAcceptFiles(TRUE) // To Accept Dropped file Set this TRUE
}

Good... That's all, and we have done well!

I added one more feature in this sample, i.e., moving our dialog by clicking on anywhere on the window. This can be done by posting the WM_NCLBUTTONDOWN message to HTCAPTION handle this statement in OnLButtonDownMessage(...) .

C++
PostMessage(WM_NCLBUTTONDOWN,HTCAPTION,MAKELPARAM(point.x,point.y))

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Technical Lead
United States United States
a hard core developer

Comments and Discussions

 
QuestionI think you can post this article as a trick or tip. right? Pin
SajeeshCheviry4-Jan-13 19:49
SajeeshCheviry4-Jan-13 19:49 
AnswerRe: I think you can post this article as a trick or tip. right? Pin
Jibesh14-Jan-13 14:18
professionalJibesh14-Jan-13 14:18 
GeneralRe: I think you can post this article as a trick or tip. right? Pin
SajeeshCheviry14-Jan-13 18:33
SajeeshCheviry14-Jan-13 18:33 
GeneralMy vote of 5 Pin
Matth Moestl13-Dec-12 1:49
professionalMatth Moestl13-Dec-12 1:49 
QuestionGreat Article Pin
JosephFox19-Feb-12 3:38
JosephFox19-Feb-12 3:38 
GeneralRe: Great Article Pin
Jibesh6-Dec-12 12:01
professionalJibesh6-Dec-12 12:01 
GeneralMy vote of 5 Pin
ThatsAlok7-Jul-11 22:16
ThatsAlok7-Jul-11 22:16 
Questionnice article Pin
ThatsAlok7-Jul-11 22:16
ThatsAlok7-Jul-11 22:16 
GeneralMy vote of 5 Pin
DemiG19-Jul-10 19:16
DemiG19-Jul-10 19:16 
GeneralDragAcceptFile Pin
Gernot Frisch18-Nov-08 0:06
Gernot Frisch18-Nov-08 0:06 
GeneralRe: DragAcceptFile Pin
Jibesh6-Dec-12 12:03
professionalJibesh6-Dec-12 12:03 
GeneralSolution: How to move your dialog by clicking on anywhere on the window in a Win32 API Non MFC App Pin
cffhgfdf22-Sep-06 2:34
cffhgfdf22-Sep-06 2:34 
Generalsimple, good, usable Pin
MGutmann11-Oct-04 21:21
MGutmann11-Oct-04 21:21 
GeneralI really like the simplicity Pin
hockeyman13-Sep-04 9:26
hockeyman13-Sep-04 9:26 
GeneralRe: I really like the simplicity Pin
hockeyman13-Sep-04 9:31
hockeyman13-Sep-04 9:31 
Generalgood job Pin
shaitan18@yahoo.com18-Feb-04 11:32
shaitan18@yahoo.com18-Feb-04 11:32 
QuestionWhom this article is targeted? Pin
super18-Nov-03 21:14
professionalsuper18-Nov-03 21:14 
AnswerRe: Whom this article is targeted? Pin
Jibesh18-Nov-03 21:35
professionalJibesh18-Nov-03 21:35 
GeneralRe: Whom this article is targeted? Pin
armentage19-Nov-03 4:50
armentage19-Nov-03 4:50 
GeneralRe: Whom this article is targeted? Pin
Jibesh19-Nov-03 5:20
professionalJibesh19-Nov-03 5:20 
QuestionHow the rating is found? Pin
kezhu18-Nov-03 13:18
kezhu18-Nov-03 13:18 
AnswerRe: How the rating is found? Pin
567890123419-Nov-03 7:44
567890123419-Nov-03 7:44 
GeneralMissing File. Pin
WREY17-Nov-03 21:22
WREY17-Nov-03 21:22 
GeneralRe: Missing File. Pin
Jibesh17-Nov-03 21:34
professionalJibesh17-Nov-03 21:34 

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