Wpf – Focus Textbox using only XAML

focustextboxwpfxaml

I'm trying to set the keyboard focus to a textbox that is included in a stackpanel collapsed by default. When the stackpanel becomes visible i want the textbox to become, by default, focused.

I've tried this code:

<StackPanel Orientation="Vertical" FocusManager.FocusedElement="{Binding ElementName=TxtB}">
  <TextBox x:Name="TxtA" Text="A" />
  <TextBox x:Name="TxtB" Text="B" />
</StackPanel>

However, it didn't work. The type cursor showed up, but it wasn't blinking and didn't allow writing.

Is it possible to solve my problem using only XAML? Perhaps triggers?

Best Answer

Yes, as you said yourself, simple trigger seems to do the trick:

<StackPanel Orientation="Vertical">
    <StackPanel.Style>
       <Style TargetType="StackPanel">
          <Style.Triggers>
              <Trigger Property="Visibility" Value="Visible">
                  <Setter Property="FocusManager.FocusedElement" 
                          Value="{Binding ElementName=TxtA}" />
              </Trigger>
          </Style.Triggers>
       </Style>
    </StackPanel.Style>

    <TextBox x:Name="TxtA" Text="A" />
    <TextBox x:Name="TxtB" Text="B" />
</StackPanel>

Related Solutions

C# – How to make a textbox that only accepts numbers

Two options:

Use a NumericUpDown instead. NumericUpDown does the filtering for you, which is nice. Of course it also gives your users the ability to hit the up and down arrows on the keyboard to increment and decrement the current value.

Handle the appropriate keyboard events to prevent anything but numeric input. I've had success with this two event handlers on a standard TextBox:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&
        (e.KeyChar != '.'))
    {
            e.Handled = true;
    }

    // only allow one decimal point
    if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1))
    {
        e.Handled = true;
    }
}

You can remove the check for '.' (and the subsequent check for more than one '.') if your TextBox shouldn't allow decimal places. You could also add a check for '-' if your TextBox should allow negative values.

If you want to limit the user for number of digit, use: textBox1.MaxLength = 2; // this will allow the user to enter only 2 digits

Android – How to stop EditText from gaining focus at Activity startup in Android

Excellent answers from Luc and Mark. However, a good code sample is missing. Adding the tags android:focusableInTouchMode="true" and android:focusable="true" to the parent layout (e.g. LinearLayout or ConstraintLayout) like in the following example, will fix the problem.

<!-- Dummy item to prevent AutoCompleteTextView from receiving focus -->
<LinearLayout
    android:focusable="true" 
    android:focusableInTouchMode="true"
    android:layout_width="0px" 
    android:layout_height="0px"/>

<!-- :nextFocusUp and :nextFocusLeft have been set to the id of this component
to prevent the dummy from receiving focus again -->
<AutoCompleteTextView android:id="@+id/autotext"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"
    android:nextFocusUp="@id/autotext" 
    android:nextFocusLeft="@id/autotext"/>

Best Answer

Related Solutions

C# – How to make a textbox that only accepts numbers

Android – How to stop EditText from gaining focus at Activity startup in Android

Related Topic