应用程序启动时将焦点放在PasswordBox上

Question

Is there a reason why I can't set the focus on my PasswordBox Control?

C#:

public Login()
{
   InitializeComponent();
   _password.Focus();
}

XAML:

<PasswordBox x:Name="_password" Width="200" Height="30" FontSize="14" 
 KeyDown="_password_KeyDown"/>

Answer 1

You're doing it too early when you're setting it in the constructor. Try the Load event handler instead.

public Login()
{
    InitializeComponent();

    this.Loaded += new RoutedEventHandler(Login_Loaded);
}

void Login_Loaded(object sender, RoutedEventArgs e)
{
    _password.Focus();
}

You can also do it in XAML:

  <Window ....
        FocusManager.FocusedElement="{Binding ElementName=_password}"
         ... />

Answer 2

WPF offers a nice elegant way (xaml only)

FocusManager.FocusedElement="{Binding ElementName=pass}">

Example:

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525"
        FocusManager.FocusedElement="{Binding ElementName=pass}">
    <Grid>
        <Button Content="Button" HorizontalAlignment="Left" Margin="261,165,0,0" VerticalAlignment="Top" Width="75"/>
        <TextBox x:Name="name" HorizontalAlignment="Left" Height="23" Margin="70,193,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
        <TextBox x:Name="pass" HorizontalAlignment="Left" Height="23" Margin="70,165,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>

    </Grid>
</Window>

Answer 3

If you want to do it in XAML :

<StackPanel FocusManager.FocusedElement="{Binding ElementName=_password}">
   <PasswordBox Name="_password" />
</StackPanel>

Please note ( MSDN ):

There can be only one element on the whole desktop that has keyboard focus. In WPF, the element that has keyboard focus will have IsKeyboardFocused set to true.