sendmessagecallbacku.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 SendMessageCallbackU;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

  {the callback function}
  procedure MessageCallback(Window: HWND; Msg: UINT; Data: DWORD;
                            LResult: LRESULT); stdcall;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
  {send the message, specifying a callback function}
  SendMessageCallback(Form1.Handle, WM_SYSCOMMAND, SC_MAXIMIZE, 0,
                      @MessageCallback, 12345);
end;

procedure MessageCallback(Window:HWND; Msg:UINT; Data:DWORD; LResult:LRESULT);
begin
  {when the message is received, this function is called}
  ShowMessage('The message callback function was called: '+IntToStr(Data));
end;

end.