限制TEdit控件只能输入数字,小数点和负号

执行这些代码，Edit1只能输入数字、小数点和负号，负号和小数点只能输入一个，负号必须在最前，粘贴的数字必须完全正确，不能以限制Ctrl_V的使用为前提。

type  TForm1 = class(TForm)    Edit1: TEdit;    procedure FormCreate(Sender: TObject);  private    Edit1OldProc: TWndMethod;    procedure Edit1NewProc(var Message: TMessage);  public    { Public declarations }  end;var  Form1: TForm1;implementation{$R *.dfm}uses Clipbrd;procedure TForm1.FormCreate(Sender: TObject);begin  Edit1OldProc := Edit1.WindowProc;  Edit1.WindowProc := Edit1NewProc;end;procedure TForm1.Edit1NewProc(var Message: TMessage);var  s: string;  v: double;begin  case Message.Msg of    WM_PASTE:      begin        s := Clipboard.astext;        s := copy(edit1.Text, 0, edit1.SelStart) + s + copy(edit1.Text, edit1.SelStart + edit1.SelLength, length(edit1.Text));        if trystrtofloat(s, v) then          Edit1OldProc(Message)        else          ShowMessage('只允许输入数字');      end;    WM_CHAR:      begin        if (TWMCHAR(Message).CharCode = 45) then          if (Pos('-', Edit1.Text) = 0) and (Edit1.SelStart = 0) then          Edit1OldProc(Message);        if (TWMCHAR(Message).CharCode = 46) then          if (Pos('.', Edit1.Text) = 0) then          Edit1OldProc(Message);        if TWMCHAR(Message).CharCode in [48..57, 8, 3] then          Edit1OldProc(Message);        if (TWMCHAR(Message).CharCode = 22)  then          Edit1OldProc(Message);      end;  else    Edit1OldProc(Message);  end;end;