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

　WM_SYSCOMMAND 消息的 LParam 參數是鼠標位置, 低位是 X, 高位是 Y.

　　下面三段程序是一樣的只是使用不同類型的消息參數, 用 TWMSysCommand 更方便, 用 TMessage 更正統.

　　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.