Получить уведомление при изменении содержимого буфера обмена

{ 
  An application can be notified of changes in the data stored in the 
  Windows clipboard by registering itself as a Clipboard Viewer. 

  Clipboard viewers use two API calls and several messages to communicate 
  with the Clipboard viewer chain. SetClipboardViewer adds a window to the 
  beginning of the chain and returns a handle to the next viewer in the chain. 
  ChangeClipboardChain removes a window from the chain. When a clipboard change occurs, 
  the first window in the clipboard viewer chain is notified via the WM_DrawClipboard 
  message and must pass the message on to the next window. To do this, our application 
  must store the next window along in the chain to forward messages to and also respond 
  to the WM_ChangeCBChain message which is sent whenever any other clipboard viewer on 
  the system is added or removed to ensure the next window along is valid. 
}


 unit
 Unit1;

 interface


 uses

   Windows, Messages, Forms, Classes, Controls, StdCtrls;

 type

   TForm1 = class
(TForm)
     Button1: TButton;
     Button2: TButton;
     procedure
 Button1Click(Sender : TObject);
     procedure
 Button2Click(Sender : TObject);
     procedure
 FormCreate(Sender : TObject);
     procedure
 FormDestroy(Sender : TObject);
   private

     FNextClipboardViewer: HWND;
     procedure
 WMChangeCBChain(var
 Msg : TWMChangeCBChain); message
 WM_CHANGECBCHAIN;
     procedure
 WMDrawClipboard(var
 Msg : TWMDrawClipboard); message
 WM_DRAWCLIPBOARD;
   end
;

 var

   Form1 : TForm1;

 implementation


 {$R *.DFM}

 procedure
 TForm1.FormCreate(Sender : TObject);
 begin

   { Initialize variable }
   FNextClipboardViewer := 0;
 end
;


 procedure
 TForm1.Button1Click(Sender : TObject);
 begin

   if
 FNextClipboardViewer <> 0 then

     MessageBox(0, 'This window is already registered!', nil
, 0)
   else

     { Add to clipboard chain }
     FNextClipboardViewer := SetClipboardViewer(Handle);
 end
;


 procedure
 TForm1.Button2Click(Sender : TObject);
 begin

   { Remove from clipboard chain }
   ChangeClipboardChain(Handle, FNextClipboardViewer);
   FNextClipboardViewer := 0;
 end
;


 procedure
 TForm1.WMChangeCBChain(var
 Msg : TWMChangeCBChain);
 begin

   inherited
;
   { mark message as done }
   Msg.Result := 0;
   { the chain has changed }
   if
 Msg.Remove = FNextClipboardViewer then

     { The next window in the clipboard viewer chain had been removed. We recreate it. }
     FNextClipboardViewer := Msg.Next
   else

     { Inform the next window in the clipboard viewer chain }
     SendMessage(FNextClipboardViewer, WM_CHANGECBCHAIN, Msg.Remove, Msg.Next);
 end
;


 procedure
 TForm1.WMDrawClipboard(var
 Msg : TWMDrawClipboard);
 begin

   inherited
;
   { Clipboard content has changed }
   try

     MessageBox(0, 'Clipboard content has changed!', 'Clipboard Viewer', MB_ICONINFORMATION);
   finally

     { Inform the next window in the clipboard viewer chain }
     SendMessage(FNextClipboardViewer, WM_DRAWCLIPBOARD, 0, 0);
   end
;
 end
;


 procedure
 TForm1.FormDestroy(Sender : TObject);
 begin

   if
 FNextClipboardViewer <> 0 then

   begin

     { Remove from clipboard chain }
     ChangeClipboardChain(Handle, FNextClipboardViewer);
     FNextClipboardViewer := 0;
   end
;
 end
;

 end
.

Другое по теме:

• Форма как графический объект
• Сохранить содержимое буфера обмена или потока как картинку
• Сохранение данных в Clipboard