Warn about CapsLock

Question

I have a DataGridTemplateColumn with DataTemplate as a PasswordBox.

I want to warn user if CapsLock is toggled.

private void PasswordBox_PasswordChan         


        

Answer 1

I have made warning balloon to solve Caps Lock warning problem in my WPF-Project.

If you want to add this balloon warning in your project then follow these steps:

- Add new Window in your project and give name "WarningBalloon".
- Add following XAML code against new Window and add warning icon to image folder of project.

<Window x:Class="MyNameSpace.WarningBalloon"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Height="160" Width="469" WindowStyle="None" ResizeMode="NoResize" ShowInTaskbar="False" Topmost="True" IsTabStop="False" OverridesDefaultStyle="False" AllowsTransparency="True" Background="Transparent" Opacity="1" >
        <Grid Height="126" Width="453">
            <Grid.RowDefinitions>
                <RowDefinition Height="81" />
                <RowDefinition Height="45*" />
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="177*" />
                <ColumnDefinition Width="72*" />
                <ColumnDefinition Width="0*" />
                <ColumnDefinition Width="170*" />
            </Grid.ColumnDefinitions>
            <Border Margin="12,32,0,0"
          CornerRadius="10,10,10,10" Grid.ColumnSpan="4" HorizontalAlignment="Left" Width="429" Height="82" VerticalAlignment="Top" Grid.RowSpan="2">
                <Border.Effect>
                    <DropShadowEffect
              Color="#FF474747" />
                </Border.Effect>
                <Border.Background>
                    <LinearGradientBrush
              EndPoint="0.5,1"
              StartPoint="0.5,0">
                        <GradientStop
                Color="#FF58C2FF"
                Offset="0" />
                        <GradientStop
                Color="#FFFFFFFF"
                Offset="1" />
                    </LinearGradientBrush>
                </Border.Background>
                <Grid Height="76" Name="grid1" Width="441">
                    <Image Height="35" HorizontalAlignment="Left" Margin="6,6,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="35" Source="/MyNameSpace;component/Images/warning-icon.png" />
                    <Label Content="Caps Lock is ON" Height="31" HorizontalAlignment="Left" Margin="125,-6,0,0" Name="lblWarningHeader" VerticalAlignment="Top" FontSize="16" FontWeight="Bold" />
                    <TextBlock HorizontalAlignment="Right" Margin="0,22,17,-1" Name="txbMessage" Width="379">Having Caps Lock on may cause you to enter your password incorrectly. <LineBreak/> <LineBreak/> You should press Caps Lock to turn it of before entering your password. VerticalAlignment="Top" Width="346" FontSize="11"</TextBlock>
                </Grid>
            </Border>
            <Image
            Source="{Binding Path=IconSource}" Width="16" HorizontalAlignment="Left" Margin="-56,0,0,-38" Height="16" VerticalAlignment="Bottom" Grid.Row="1" />
            <Path Data="M10402.99154,55.5381L10.9919,0.64 0.7,54.9" Fill="LightSkyBlue" HorizontalAlignment="Left" Margin="32,3,0,0" Stretch="Fill" Stroke="Black" Width="22" Height="31" VerticalAlignment="Top" />
        </Grid>
    </Window>

- Type the following code behind the LoginForm.

    private Point location;
    public static  bool balloonVisFlag = false;
    private DispatcherTimer timer;
    WarningBalloon Balloon = null;

    private void ShowHideBalloon()
    {            
        if (System.Windows.Forms.Control.IsKeyLocked(System.Windows.Forms.Keys.CapsLock))
        {
            if (timer == null)
            {
                timer = new DispatcherTimer();
            }
            location = GetControlPosition(psbPassword);
            Balloon.Left = location.X;
            Balloon.Top = location.Y;
            Balloon.Show();
            balloonVisFlag = true;
            timer.Interval = TimeSpan.FromMilliseconds(5000);
            timer.IsEnabled = true;
            timer.Tick += new EventHandler(Timer_Tick);
            psbPassword.Focus();
        }
        else
        {
            Balloon.Hide();
            balloonVisFlag = false;
            psbPassword.Focus();
        }
    }

    Point GetControlPosition(Control myControl)
    {
        Point locationToScreen = myControl.PointToScreen(new Point(0, 0));
        PresentationSource source = PresentationSource.FromVisual(myControl);
        return source.CompositionTarget.TransformFromDevice.Transform(locationToScreen);
    }     

    private void psbPassword_KeyDown(object sender, KeyEventArgs e)
    {
        ShowHideBalloon();
    }

    private void Window_LocationChanged(object sender, EventArgs e)
    {
        if (balloonVisFlag == true)
        {
            ShowHideBalloon();
        }
    }

    private void Timer_Tick(object sender, EventArgs e)
    {
        if (balloonVisFlag == true)
        {
            Balloon.Hide();
            balloonVisFlag = false;
        }
    }    
}

Answer 2

It completely depends on your architecture, but for a simple solution:

You should be setting a Dependency Property, which will be observed by some sort of control on the Window that will become visible and will display the warning for the user.

Answer 3

My solution is a little bit different. I made a ContentControl you can put anything inside of, and it will notify the caps lock status. Add this class to your code.

  public sealed class ShowCapLock : ContentControl
  {
    public bool ShowMessage
    {
      get { return (bool)GetValue(ShowMessageProperty); }
      set { SetValue(ShowMessageProperty, value); }
    }
    public static readonly DependencyProperty ShowMessageProperty =
        DependencyProperty.Register("ShowMessage", typeof(bool), typeof(ShowCapLock), new PropertyMetadata(false));

    static ShowCapLock()
    {
      DefaultStyleKeyProperty.OverrideMetadata(typeof(ShowCapLock), new FrameworkPropertyMetadata(typeof(ShowCapLock)));
    }

    public ShowCapLock()
    {
      IsKeyboardFocusWithinChanged += (s,e) => RecomputeShowMessage();
      PreviewKeyDown += (s,e)=> RecomputeShowMessage();
      PreviewKeyUp += (s,e)=> RecomputeShowMessage();
    }

    private void RecomputeShowMessage()
    {
      ShowMessage = IsKeyboardFocusWithin && System.Console.CapsLock;
    }
  }

And add some XAML to your generic.xaml

<Style TargetType="{x:Type controls1:ShowCapLock}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type controls1:ShowCapLock}">
                <Grid>
                    <ContentPresenter Name="Presenter"/>
                    <Popup Placement="Bottom" PlacementTarget="{Binding ElementName=Presenter}" 
                           IsOpen="{TemplateBinding ShowMessage}">
                        <Border Background="LightGoldenrodYellow" BorderThickness="1" BorderBrush="Black">
                            <TextBlock Foreground="Black">
                                <TextBlock>Caps Lock is down.</TextBlock>
                            </TextBlock>
                        </Border>
                    </Popup>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

And you can put a little control around anything you want to notify for caps lock:

            <controls:ShowCapLock Grid.Row="5" Grid.Column="1">
                <PasswordBox  . . ./>
            </controls:ShowCapLock>

Answer 4

You could show a ToolTip

private void PasswordBox_KeyDown(object sender, KeyEventArgs e)
{
    if ((Keyboard.GetKeyStates(Key.CapsLock) & KeyStates.Toggled) == KeyStates.Toggled)
    {
        if (PasswordBox.ToolTip == null)
        {
            ToolTip tt = new ToolTip();
            tt.Content = "Warning: CapsLock is on";
            tt.PlacementTarget = sender as UIElement;
            tt.Placement = PlacementMode.Bottom;
            PasswordBox.ToolTip = tt;
            tt.IsOpen = true;
        }
    }
    else
    {
        var currentToolTip = PasswordBox.ToolTip as ToolTip;
        if (currentToolTip != null)
        {
            currentToolTip.IsOpen = false;
        }

        PasswordBox.ToolTip = null;
    }
}