Hook на буфер обмена

{ 
  *Just create a new form and call it ClipFormats. 
  *Drop a TButton and call it btnUpdate. 
  *Drop a TListBox and call it lbFormats. 

  Then just add the code below and hook up all the event handlers. 
  All it does is display all the formats currently on the clipboard and 
  updates as soon as the clipboard changes. 
}

unit DynaClip;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TClipFormats = class(TForm)
    btnUpdate: TButton;
    lbFormats: TListBox;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure btnUpdateClick(Sender: TObject);
  private
    { Private declarations }
    NextWindow: HWND;
    procedure WMChangeCBChain(var Message: TWMChangeCBChain); message
    WM_CHANGECBCHAIN;
    procedure WMDrawClipboard(var Message: TWMDrawClipboard); message
    WM_DRAWCLIPBOARD;
  public
    { Public declarations }
  end;

var
  ClipFormats: TClipFormats;

implementation

{$R *.DFM}

procedure TMDIChildClipFormats.FormCreate(Sender: TObject);
begin
  NextWindow := SetClipboardViewer(Handle);
end;

procedure TClipFormats.FormDestroy(Sender: TObject);
begin
  ChangeClipboardChain(Handle, NextWindow);
end;

procedure TClipFormats.WMChangeCBChain(var Message: TWMChangeCBChain);
begin
  with Message do
  begin
    if (Remove = NextWindow) then
    begin
      NextWindow := Next;
    end
    else
    begin
      SendMessage(NextWindow, WM_CHANGECBCHAIN, Remove, Next);
    end;
  end;
end;

procedure TClipFormats.WMDrawClipboard(var Message: TWMDrawClipboard);
begin
  btnUpdate.Click;
  SendMessage(NextWindow, WM_DRAWCLIPBOARD, 0, 0);
end;

procedure TClipFormats.btnUpdateClick(Sender: TObject);
const
  PreDefinedFormats: array[1..16] of string = (
    'CF_TEXT',
    'CF_BITMAP',
    'CF_METAFILEPICT',
    'CF_SYLK',
    'CF_DIF',
    'CF_TIFF',
    'CF_OEMTEXT',
    'CF_DIB',
    'CF_PALETTE',
    'CF_PENDATA',
    'CF_RIFF',
    'CF_WAVE',
    'CF_UNICODETEXT',
    'CF_ENHMETAFILE',
    'CF_HDROP',
    'CF_LOCALE');
var
  ClipFormat: TClipFormat;
  szBuffer: array[0..511] of Char;
  FormatID: string;
begin
  if not OpenClipboard(Handle) then Exit;
  try
    lbFormats.Items.BeginUpdate;
    try
      lbFormats.Items.Clear;

      ClipFormat := EnumClipboardFormats(0);
      while (ClipFormat <> 0) do
      begin
        if (ClipFormat in [1..16]) then
        begin
          FormatID := PreDefinedFormats[ClipFormat];
        end
        else
        begin
          GetClipboardFormatName(ClipFormat, szBuffer, SizeOf(szBuffer));
          FormatID := string(szBuffer);
        end;
        lbFormats.Items.Add(Format('%s [%d]', [FormatID, ClipFormat]));
        ClipFormat := EnumClipboardFormats(ClipFormat);
      end;
    finally
      lbFormats.Items.EndUpdate;
    end;
  finally
    CloseClipboard;
  end;
end;

end.