Let them drag and drop files on your program
If you want to let your users drag and drop files on your program from the File Manager and Windows Explorer, simply add the code inside
//>>> and
//<<< to your program as in the following example:
unit dropfile;
interface
uses
Windows, Messages, SysUtils, Classes,
Graphics, Controls, Forms, Dialogs;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
//>>>
// 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 your thing with the acFileName
MessageBox( Handle, acFileName, '', MB_OK );
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 );
//<<<
end;
end.
Listing #1 : Delphi code. Download
dropfile (0.8 KB).
Now you can drag and drop files on the form that you registered as a recipient of dropped files by calling the "DragAcceptFiles()" function as in the above example.
Applicable Keywords : Delphi, Delphi 1.x, Delphi 2.x, Delphi 3.x, Functions, Source Code, Win32