How-to-hook-into-the-Clipboard-Notification-Chain


            Title: How to hook into the Clipboard Notification Chain
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.
System Delphi
