学习 Message(4): 通过 Application.OnMessage 或 TApplicationEvents 响应消息

通过 Application.OnMessage 响应消息:

---

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Memo1: TMemo;

    procedure FormCreate(Sender: TObject);

    {这个自定义过程要复合 Application.OnMessage 的参数格式}

    procedure MyMessage(var Msg: tagMSG; var Handled: Boolean);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.FormCreate(Sender: TObject);

begin

  Memo1.Clear;

  Application.OnMessage := MyMessage; {让 Application.OnMessage 执行自定义过程}

end;



{响应 WM_MOUSEMOVE 以外的所有消息}

procedure TForm1.MyMessage(var Msg: tagMSG; var Handled: Boolean);

begin

  if Msg.message <> WM_MOUSEMOVE then

    Memo1.Lines.Add('$' + IntToHex(Msg.message, 4));

end;



end.


 
   

通过 TApplicationEvents 响应消息, 需要在设计时添加 TApplicationEvents 组件, 并给它添加 OnMessage 事件:

---

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, AppEvnts;



type

  TForm1 = class(TForm)

    Memo1: TMemo;

    ApplicationEvents1: TApplicationEvents;

    procedure FormCreate(Sender: TObject);

    procedure ApplicationEvents1Message(var Msg: tagMSG; var Handled: Boolean);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.FormCreate(Sender: TObject);

begin

  Memo1.Clear;

end;



{响应 WM_MOUSEMOVE 以外的所有消息}

procedure TForm1.ApplicationEvents1Message(var Msg: tagMSG;

  var Handled: Boolean);

begin

  if Msg.message <> WM_MOUSEMOVE then

    Memo1.Lines.Add('$' + IntToHex(Msg.message, 4));

end;



end.