messageextrainfou.pas

DelphiWin32核心API参考光盘内容.是学习书籍中的源码,便于学习.

unit MessageExtraInfoU;

interface

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

{define an application specific user message}
const
  UserMessage = WM_USER+1;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    {the handler for our user message}
    procedure DoMessage(var Msg: TMessage); message UserMessage;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
  {set the message extra information}
  SetMessageExtraInfo(12345);

  {send the user message to the window}
  Perform(UserMessage, 0, 0);
end;

procedure TForm1.DoMessage(var Msg: TMessage);
begin
  {the user message was retrieved, show the message extra info}
  Button1.Caption := 'User Message Received. Info: '+
                      IntToStr(GetMessageExtraInfo);
end;

end.