如何隐藏标签，直到输入了文本框信息

Question

I'm trying to have a label hidden until numbers have been entered in a texbox by the user. Then I want the label to show up. I'm hoping to have this all inside XAML without using C#.

I've tried different types of binding based on things I found online. I think I must be close but something is still off.

Here's the textbox code:

<TreeViewItem Grid.Row="1" FontSize="12" Header="Width"/>
<TextBox Text="{Binding xcoord, UpdateSourceTrigger=PropertyChanged}" Name="x" Height="20" Width="40" Grid.Row="1" Grid.Column="2" />

Here's the label code:

<Label Foreground="SteelBlue" FontWeight="Bold" HorizontalAlignment="Center" VerticalContentAlignment="Center" Height="40" Background="Transparent" x:Name="label1"  FontSize="16" Width="160"  Content="{Binding Text, ElementName=x}" ContentStringFormat=" {0} mm" Canvas.Left="220" Canvas.Top="382" RenderTransformOrigin="1.045,-0.141" VerticalAlignment="Top">
                    <Label.Style>
                        <Style TargetType="Label">
                            <Setter Property="Visibility" Value="Hidden" />
                            <Style.Triggers>
                                <DataTrigger Binding="{Binding Text.Length, ElementName=x, UpdateSourceTrigger=PropertyChanged}" Value="True">
                                    <Setter Property="Visibility" Value="Visible"/>
                                </DataTrigger>
                            </Style.Triggers>
                        </Style>
                    </Label.Style>

                </Label>

Basically anything I've tried just doesn't show the label on screen at all.

Answer 1

Something like that might work - will hide label if texbox text is empty

<TextBox x:Name "tb1"/>
<Label Foreground="SteelBlue" FontWeight="Bold" HorizontalAlignment="Center" VerticalContentAlignment="Center" Height="40" Background="Transparent" x:Name="label1"  FontSize="16" Width="160"  Content="{Binding Text, ElementName=x}" ContentStringFormat=" {0} mm" Canvas.Left="220" Canvas.Top="382" RenderTransformOrigin="1.045,-0.141" VerticalAlignment="Top">
    <Label.Style>
        <Style TargetType="Label">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Text, ElementName=tb1}" Value="">
                    <Setter Property="Visibility" Value="Hidden" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Label.Style>
</Label>