Drag and Drop from FileManager

You need to use these 3 functions from the ShellApi:

DragAcceptFiles - registers whether a window accepts dropped files

DragQueryFile - retrieves the filename of a dropped file

DragFinish - releases memory allocated for dropping files

uses

ShellApi;

..

procedure TForm1.FormCreate(Sender: TObject);

begin

DragAcceptFiles(Form1.Handle, true);

Application.OnMessage := AppMessage;

end;

{ message handler procedure }

// Delphi 1: type DWord = longint; .. FileIndex := -1;

procedure TForm1.AppMessage(var Msg: Tmsg; var Handled: Boolean);

const

BufferLength : DWORD = 511;

var

DroppedFilename : string;

FileIndex : DWORD;

NumDroppedFiles : DWORD;

pDroppedFilename : array [ ..511] of Char;

DroppedFileLength : DWORD;

begin

if Msg.message = WM_DROPFILES then

begin

FileIndex := $FFFFFFFF;

NumDroppedFiles := DragQueryFile(Msg.WParam, FileIndex,

pDroppedFilename, BufferLength);

for FileIndex := 0 to (NumDroppedFiles - 1) do

begin

DroppedFileLength := DragQueryFile(Msg.WParam, FileIndex,

pDroppedFilename,

BufferLength);

DroppedFilename := StrPas(pDroppedFilename);

{ process the file name you just received }

end;

DragFinish(Msg.WParam); { important to free memory }

Handled := true;

end;

end;

Notes:

When dropping files, the DroppedFilename is the complete path, not just the filename.ext

It is possible to drag and drop just a directory. So if you are expecting filenames, you have to check for existence yourself.

The filenames come in uppercased.