如果文本框不为空，如何添加和显示工具提示文本框WPF

Question

Need to show a hint, which contains data from a text field. Prompt to appear if the textbox has data.

Answer 1

Just use binding to ToolTipService attached properties. XAML:

<UserControl.Resources>
    <converters:IsStringNonemptyConverter x:Key="ToolTipVisibilityConveter" />
</UserControl.Resources>

<TextBox Name="textBox" VerticalAlignment="Center" HorizontalAlignment="Center" Width="150"
         ToolTipService.ToolTip="{Binding Text, RelativeSource={RelativeSource Self}}"
         ToolTipService.IsEnabled="{Binding Text, RelativeSource={RelativeSource Self}, Converter={StaticResource ToolTipVisibilityConveter}}"/>

Converter:

internal sealed class IsStringNonemptyConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return !String.IsNullOrEmpty(value as string);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

Answer 2

You can disable the tooltip using triggers. Place this style in your window or App resources so that it can be shared across all the textboxes in your window or application depending on your choice -

<Style x:Key="{x:Type TextBox}" TargetType="TextBox">
  <Style.Triggers>
     <Trigger Property="ToolTip" Value="{x:Static sys:String.Empty}">
        <Setter Property="ToolTipService.IsEnabled" Value="False" />
      </Trigger>
</Style.Triggers>

Make sure you add the system namespace to your xaml -

xmlns:sys="clr-namespace:System;assembly=mscorlib"

Answer 3

I had this problem myself and figured out a different solution. I know this question has been answered but just like me there will still be people coming across this question, and I would like to share my solution:

XAML

<TextBox Name="textBox1" ToolTip="{Binding Text, RelativeSource={RelativeSource Self}}" ToolTipService.IsEnabled="False"/>

Code behind

private void textBox1_TextChanged(object sender, TextChangedEventArgs e)
{
    if (textBox1.Text.Length > 0)
    {
        ToolTipService.SetIsEnabled(textBox1, true);
    }
}

I hope this helps someone.

Answer 4

I tried with Visibility Mode & TextChange event. ToolTip invisible when no text. May be useful for someother. Xaml:

    <TextBox Height="23" Width="100" Name="myTextBox" TextChanged="myTextBox_TextChanged" >
        <TextBox.ToolTip>
            <ToolTip Visibility="Hidden">
                <TextBlock Name="toolTipTextBlock"></TextBlock>
            </ToolTip>            
        </TextBox.ToolTip>
    </TextBox>

TextChange event handler:

    private void myTextBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        TextBox tb = sender as TextBox;

        if (tb.Text.Trim() == "")
        {
            ((ToolTip)tb.ToolTip).Visibility = Visibility.Hidden;
        }
        else
        {
            toolTipTextBlock.Text = tb.Text;
            ((ToolTip)tb.ToolTip).Visibility = Visibility.Visible;
        }
    }