學習 Message(18): WM_SYSCOMMAND 訊息[二] : LParam 參數

WM_SYSCOMMAND 訊息的 LParam 參數是滑鼠位置, 低位是 X, 高位是 Y.

下面三段程式是一樣的只是使用不同類型的訊息參數, 用 TWMSysCommand 更方便, 用 TMessage 更正統.

程式一:

unit Unit1;interfaceuses  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.

程式二:

unit Unit1;interfaceuses  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.

程式三:

unit Unit1;interfaceuses  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.