Passworteingabe, wie mit Sternchen verstecken, aber nicht das letzte Zeichen?

[Sir Rufo]

Oder einfach so

Delphi-Quellcode:

unit Forms.MainForm;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls, Vcl.Buttons;

type
  TMainForm = class( TForm )
    PasswordLabel: TLabel;
    Num0Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num1Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num2Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num3Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num4Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num5Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num6Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num7Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num8Button: TSpeedButton;      {OnClick -> NumButtonClick}
    Num9Button: TSpeedButton;      {OnClick -> NumButtonClick}
    ClearButton: TSpeedButton;     {OnClick -> ClearButtonClick}
    BackspaceButton: TSpeedButton; {OnClick -> BackspaceButtonCLick}
    Timer1: TTimer;
    procedure Timer1Timer( Sender: TObject );
    procedure FormShow( Sender: TObject );
    procedure NumButtonClick( Sender: TObject );
    procedure BackspaceButtonClick( Sender: TObject );
    procedure ClearButtonClick( Sender: TObject );
  private
    FPassword: string;
    procedure AddKey( const AChar: Char );
    procedure ClearPassword;
    procedure PresentPassword;
  public
    property Password: string read FPassword;
  end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

uses
  System.StrUtils;

{ TMainForm }

procedure TMainForm.AddKey( const AChar: Char );
begin
  case AChar of
    #8:
      begin
        if Length( FPassword ) > 0
        then
          begin
            SetLength( FPassword, Length( FPassword ) - 1 );
            PasswordLabel.Caption := DupeString( '*', Length( FPassword ) );
          end;
      end;
    '0' .. '9':
      begin
        Timer1.Enabled        := False;
        PasswordLabel.Caption := DupeString( '*', Length( FPassword ) ) + AChar;
        FPassword             := FPassword + AChar;
        Timer1.Enabled        := True;
      end;
  end;
end;

procedure TMainForm.BackspaceButtonClick( Sender: TObject );
begin
  AddKey( #8 );
end;

procedure TMainForm.ClearButtonClick( Sender: TObject );
begin
  ClearPassword;
end;

procedure TMainForm.ClearPassword;
begin
  FPassword             := '';
  PasswordLabel.Caption := '';
end;

procedure TMainForm.FormShow( Sender: TObject );
begin
  PresentPassword;
end;

procedure TMainForm.NumButtonClick( Sender: TObject );
var
  Button: TComponent absolute Sender;
begin
  AddKey( Button.Name[ 4 ] ); // Ich bin halt faul ;o)
end;

procedure TMainForm.PresentPassword;
begin
  PasswordLabel.Caption := DupeString( '*', Length( FPassword ) );
end;

procedure TMainForm.Timer1Timer( Sender: TObject );
begin
  TTimer( Sender ).Enabled := False;
  PresentPassword;
end;

end.

Und falls nun doch die Tastatur zugelassen werden soll, dann erreicht man das ganz simpel mit

Delphi-Quellcode:

procedure TMainForm.FormKeyPress( Sender: TObject; var Key: Char );
begin
  AddKey( Key );
end;