Dragging and Dropping

I want to create a deplhi application that

is capable of making the user able to drag

and drop graphical objects like a line or

something! I want to be able to create an

OnDblClick event for this line after it is

dragged in my form! How can I do so?

// Maybe this is what you want. If not email me.

// Reginaldo Ap. Rigo

// virtual@alphanet.com.br





// Hope it helps.

unit DragnDrop;



interface



uses

*Windows, Messages, SysUtils, Classes,

*Graphics, Controls, Forms, Dialogs,

*extctrls, StdCtrls;



type

*TForm1 = class(TForm)

* *procedure FormCreate(Sender: TObject);

* *procedure ImageClick(Sender: TObject);

*private

* *{ Private declarations }

*public

* *ImageNum : Integer;

* *Image : TImage;

* *//>>>

* *// declare our DROPFILES message handler

* *procedure AcceptFiles( var msg : TMessage );

* * * * * * *message WM_DROPFILES;

* *//<<<

*end;



var

*Form1: TForm1;





implementation

uses

*//

*// this unit contains certain

*// functions that we'll be using

*//

*//>>>

*ShellAPI;

*//<<<

{$R *.DFM}

//>>>



procedure TForm1.AcceptFiles( var msg : TMessage );

const

*cnMaxFileNameLen = 255;

var

*i,

*nCount * * : integer;

*acFileName : array [ 0 .. cnMaxFileNameLen ] of char;

begin

*// find out how many files we're accepting

*nCount := DragQueryFile( msg.WParam,

* * * * * * * * * * * * * $FFFFFFFF,

* * * * * * * * * * * * * acFileName,

* * * * * * * * * * * * * cnMaxFileNameLen );

*// query Windows one at a time for the file name

*for i := 0 to nCount-1 do

*begin

* *DragQueryFile( msg.WParam, i,

* * * * * * * * * acFileName, cnMaxFileNameLen );

* *// do our thing with the acFileName

* *if *StrUpper(PChar(ExtractFileExt( acFileName ))) ='.BMP' then

* *// We handling just .bmp files for now.

* *begin

* * * Image := TImage.Create( Self );

* * * with Image do

* * * begin

* * * * AutoSize := true;

* * * * Picture.LoadFromFile( acFileName );

* * * * Tag := ImageNum;

* * * * OnClick := ImageClick;

* * * * Parent := Form1;

* * * * Left := ImageNum * 10;

* * * * Top *:= ImageNum * 20;

* * * end;

* * * Inc( ImageNum );

* *end;

*end;

*// let Windows know that you're done

*DragFinish( msg.WParam );

end;

//<<<

procedure TForm1.FormCreate(Sender: TObject);

begin

*// tell Windows that you're

*// accepting drag and drop files

*//>>>

*DragAcceptFiles( Handle, True );

*//<<
*ImageNum := 1;

end;



procedure TForm1.ImageClick(Sender: TObject);

begin

* *Form1.Caption := 'There was a click on the '+ IntToStr(( Sender as TImage ).Tag )+ ' image!';

end;



end.