Как сделать Drag-n-Drop из чужого приложения?

Code:

{

The following example demonstrates the Drag&Drop machanism from an external

application (Wordpad, Microsoft,..) to a TMemo in your own application.

}

unit TMemoDragDropFrm;

{ ****************************************************************

Source File Name :  TMemoDragDropFrm.pas

Typ              :  Hauptformular

Autor            :  Andreas Kosch

Compiler         :  Delphi 4.02 CSS

Betriebssystem   :  Windows 98

Beschreibung     :  Text via OLE Drag&Drop ubernehmen aus einer

                     anderen Anwendung (wie zum Beispiel WordPad)

                     ubernehmen.

16.01.2003: Test mit Delphi 7 und Microsoft Word XP unter Windowx XP

**************************************************************** }

{ Comments by Thomas Stutz }

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, ComCtrls, ActiveX, ShlObj, ComObj, StdCtrls;

type

// TForm1's declaration indicates that it's a TForm and that

// it supports the IDropTarget interface:

{

IDropTarget

Any application wanting to accept drop operations must

implement the IDropTarget interface.

Methods of the IDropTarget interface:

DragEnter

   Dragged item has just been moved into the application's window,

   return the relevant icon.

DragOver

   Dragged item is being moved over the application's window,

   return the relevant icon.

DragLeave

   Dragged item has just moved out of the application's window.

Drop

   The dragged item has been dropped on this application.

}

TForm1 = class(TForm, IDropTarget)

   Memo1: TMemo;

   procedure FormCreate(Sender: TObject);

   procedure FormDestroy(Sender: TObject);

private

   // IDropTarget

   function DragEnter(const dataObj: IDataObject;

                      grfKeyState: Longint;

                      pt: TPoint;

                      var dwEffect: Longint): HResult; stdcall;

   function DragOver(grfKeyState: Longint;

                     pt: TPoint;

                     var dwEffect: Longint): HResult; stdcall;

   function DragLeave: HResult; stdcall;

   function Drop(const dataObj: IDataObject;

                 grfKeyState: Longint; pt: TPoint;

                 var dwEffect: Longint): HResult; stdcall;

  // IUnknown

  // Ignore referance counting

  function _AddRef: Integer; stdcall;

  function _Release: Integer; stdcall;

public

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

uses

ShellAPI;

// In the OnCreate event handler, two important methods are called.

// First, OleInitalize is called. This initializes the OLE libraries and should always be

// called before your application uses any OLE functions.

// RegisterDragDrop registers the window as a valid drop target.

// If this isn't called, the window will never receive any drop events.

procedure TForm1.FormCreate(Sender: TObject);

begin

OleInitialize(nil);

{Allow window to accept drop events}

OleCheck(RegisterDragDrop(Handle, Self));

{ Execute Wordpad for testing }

ShellExecute(Handle, 'open', 'wordpad', 'c:\Test.doc', nil, SW_SHOW);

end;

// OnDestroy does the exact opposite. It calls RevokeDropTarget to indicate that

// drop events are no longer accepted.

// It then calls OleUninitialize, since the application is finished using all OLE functions.

procedure TForm1.FormDestroy(Sender: TObject);

begin

{Finished accepting drops}

RevokeDragDrop(Handle);

OleUninitialize;

end;

{-----------------------------------------------------------------}

{ IDropTarget-Implementierung                                     }

{-----------------------------------------------------------------}

function TForm1.DragEnter(const dataObj: IDataObject;

grfKeyState: Longint;

pt: TPoint;

var dwEffect: Longint): HResult;

begin

dwEffect := DROPEFFECT_COPY;

Result  := S_OK;

end;

function TForm1.DragOver(grfKeyState: Longint;

pt: TPoint;

var dwEffect: Longint): HResult;

begin

dwEffect := DROPEFFECT_COPY;

Result := S_OK;

end;

function TForm1.DragLeave: HResult;

begin

Result := S_OK;

end;

function TForm1._AddRef: Integer;

begin

  Result := 1;

end;

function TForm1._Release: Integer;

begin

  Result := 1;

end;

function TForm1.Drop(const dataObj: IDataObject;

grfKeyState: Longint;

pt: TPoint;

var dwEffect: Longint): HResult;

var

aFmtEtc: TFORMATETC;

aStgMed: TSTGMEDIUM;

pData: PChar;

begin

{Make certain the data rendering is available}

if (dataObj = nil) then

   raise Exception.Create('IDataObject-Pointer is not valid!');

with aFmtEtc do

begin

   cfFormat := CF_TEXT;

   ptd := nil;

   dwAspect := DVASPECT_CONTENT;

   lindex := -1;

   tymed := TYMED_HGLOBAL;

end;

{Get the data}

OleCheck(dataObj.GetData(aFmtEtc, aStgMed));

try

   {Lock the global memory handle to get a pointer to the data}

   pData := GlobalLock(aStgMed.hGlobal);

   { Replace Text }

   Memo1.Text := pData;

finally

   {Finished with the pointer}

   GlobalUnlock(aStgMed.hGlobal);

   {Free the memory}

   ReleaseStgMedium(aStgMed);

end;

Result := S_OK;

end;

end.