如果文本框包含文本WPF，则在tabcontrol选项卡标题中显示图像

Question

Okay, What I'm trying to accomplish:

A tabheader which gets an image if the textbox inside has text. but if the textbox inside the TabItem doesn't have any text, then the image should not be shown.

this is what I have so far:

----- TAB ITEM CODE -----

            <TabItem Name="tabAantekeningen"  Header="">
                <TabItem.HeaderTemplate>
                    <DataTemplate>
                        <Grid>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition></ColumnDefinition>
                                <ColumnDefinition></ColumnDefinition>
                            </Grid.ColumnDefinitions>

                            <TextBlock Grid.Column="0" Margin="8" Text="Aantekeningen"/>
                            <Image Grid.Column="1" Source="..\Resources\validate.png" Height="20" Width="17"/>
                        </Grid>
                    </DataTemplate>
                </TabItem.HeaderTemplate>
                <TextBox Name="txtOmschrijving" TextWrapping="Wrap" AcceptsReturn="True"></TextBox>
            </TabItem>

----- TAB ITEM CODE -----

----- Code Behind -----

    public void SetTabItemHeader()
    {
        if (String.IsNullOrEmpty(txtOmschrijving.Text))
        {
            tabAantekeningen.Header = "Aantekeningen";
        }
    }

----- Code Behind -----

IS there a way that I can say: txtOmschrijving.Text == Empty so hide the Image?

Answer 1

Edit: Didn't see your seccond question there, yes there is use a IValueConverter , where you check if the string is empty and Bind To Visibility for instance, so you return Visbility.Collapsed when empty or else Visbility.Visible. Like this :

public class StringEmptyToVisbililityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (value == null) || !(value is string) || string.IsNullOrEmpty(value.ToString()) ? Visibility.Collapsed : Visibility.Visible;
    }

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

Fully working xaml, change your namespaces and URI pack

<Window x:Class="TabItemHeader.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        
    xmlns:local="clr-namespace:TabItemHeader"
    Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <local:StringEmptyToVisbililityConverter x:Key="StringEmptyToVisbililityConverter"/>
</Window.Resources>
<Grid>        
    <TabControl>
        <TabItem Name="tabAantekeningen">
            <TabItem.HeaderTemplate>
                <DataTemplate>
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition/>
                            <ColumnDefinition/>
                        </Grid.ColumnDefinitions>
                        <TextBlock Grid.Column="0" Margin="8" Text="{Binding Path='Header',RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TabItem}}}"/>
                        <Image Grid.Column="1" Source="pack://application:,,,/TabItemHeader;component/Resources/Images/validate.png" Height="20" Width="17" Visibility="{Binding Path='Header', Converter={StaticResource StringEmptyToVisbililityConverter}, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TabItem}}}"/>
                    </Grid>
                </DataTemplate>
            </TabItem.HeaderTemplate>
            <TextBox Name="txtOmschrijving" TextWrapping="Wrap" AcceptsReturn="True"></TextBox>
        </TabItem>
    </TabControl>
</Grid>

This will bind to the listboxitem which wraps everything in a listbox. The converter will only show this image when the string is not empty. You can do alot of fun with them :)

WPF cheat sheet is a really handy and compact paper on all types of bindings.

Oh..I am assuming this image will be deployed with your application? Then please ensure that your image is set to resource, you should consider using uri packs as well for your images, an example is in this post as well as the xaml provided. If your image is dynamic, you will have to bind them to some model in an observablecollection. Tip: I'll stop pushing this to far, but you should consider having a look at the MVVM pattern. I just used code behind my self, so the answer wouldn't get to big. It's whole other topic! =) There are also cleaner ways to either share templates, and change them on types bound in the collection.

Hope it helps.

Cheers,

Stian