学习 Message(18): WM_SYSCOMMAND 消息[二] : LParam 参数

WM_SYSCOMMAND 消息的 LParam 参数是鼠标位置, 低位是 X, 高位是 Y.

下面三段程序是一样的只是使用不同类型的消息参数, 用 TWMSysCommand 更方便, 用 TMessage 更正统.

---

程序一:

---

unit Unit1;



interface



uses

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

  Dialogs;



type

  TForm1 = class(TForm)

  protected

    procedure WMSysCommand(var Message: TWMSysCommand); message WM_SYSCOMMAND;

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.WMSysCommand(var Message: TWMSysCommand);

begin

  Text := Format('%d,%d', [Message.XPos, Message.YPos]);

  inherited;

end;



end.


 
   

程序二:

---

unit Unit1;



interface



uses

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

  Dialogs;



type

  TForm1 = class(TForm)

  protected

    procedure WMSysCommand(var Message: TMessage); message WM_SYSCOMMAND;

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.WMSysCommand(var Message: TMessage);

begin

  Text := Format('%d,%d', [LoWord(Message.LParam), HiWord(Message.LParam)]);

  inherited;

end;



end.


 
   

程序三:

---

unit Unit1;



interface



uses

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

  Dialogs;



type

  TForm1 = class(TForm)

  protected

    procedure WMSysCommand(var Message: TMessage); message WM_SYSCOMMAND;

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.WMSysCommand(var Message: TMessage);

begin

  Text := Format('%d,%d', [Message.LParamLo, Message.LParamHi]);

  inherited;

end;



end.