Develop Reference

XAML/C# Hiding a TextBlock if the bound value is empty

in my WPF application I have a listview that only appears if a bound item has an values, this works like so
<ListView Grid.Row="1" Grid.Column="1" Margin="0,5,0,20" BorderThickness="0"
ItemContainerStyle="{StaticResource SelectionlessListViewItemStyle}"
ItemsSource="{Binding MissingAssets}">
<ListView.Style>
<Style TargetType="ListView">
<Style.Triggers>
<Trigger Property="HasItems" Value="False">
<Setter Property="Visibility" Value="Collapsed"></Setter>
</Trigger>
</Style.Triggers>
</Style>
</ListView.Style>
So this will only display the listview if MissingAssets has any values and works fine, above that I wanted a textblock as a header to just say "The following assets could not be found", and I want to hide this text of course if this listview is hidden too, I tried implementing it like this
<TextBlock Grid.Row="0" Grid.Column="1" VerticalAlignment="Center" FontWeight="Bold" Text="The following assets could not be found">
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Style.Triggers>
<DataTrigger Binding="{Binding MissingAssets}" Value="">
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
But for some reason it won't hide even if MissingAssets is empty, I've tried using several different things in Value="" but nothing gets it to work. Is there a property or something I'm forgetting to set?
Thanks

You have many options here. The simplest should be to bind the TextBlock.Visibility to the ListView.Visibilty:
<StackPanel>
<TextBlock Visibility="{Binding Elementname="MissingAssetsListView", Path="Visbibility" />
<ListView x:Name="MissingAssetsListView" />
</StackPanel>

Found a workaround, I created a new string property in my C# code that remains blank unless missing assents are found, if they are found I populate the string and bind that string to a label in my XAML, so if the string is empty then there will be no visible label on the UI

How to avoid childrens of groupbox taking there default styles which are defined in resource or resourcedictionary in wpf

Style defined in Resource
<Setter Property="Background" Value="Red"/>
</Style>enter code here
</Window.Resources>
In window i am adding a groupbox with child label .
<Grid>
<GroupBox Header="Header">
<GroupBox.Resources>
<Style TargetType="{x:Type GroupBox}">
<Setter Property="Background" Value="white"/>
</Style>
</GroupBox.Resources>
<Label Content="dsfdsfdsf" Foreground="Black" />
</GroupBox>
</Grid>
My Expected Result was Label taking background of white . But actually it is taking Red Background (that is defined in style of Resource )
If i set the style of the Label to explicitly null it works fine
Label Content="dsfdsfdsf" Foreground="Black" Style={x:Null}
But Controls to GroupBox are dynamically added so i want to set
Style={x:Null} to all childrens that are being added to Group box
if i set OverrideDefalutStyle to True in Label the content of label is not comming ......................
Label Content="dsfdsfdsf" Foreground="Black" OverridesDefaultStyle="True"

That style in GroupBox.Resources has no effect on the GroupBox itself. The implicit GroupBox's style is the one of its closest ancestor on VisualTree. You put that style in the wrong place.
Or use Style property instead
<Grid>
<GroupBox Header="Header">
<GroupBox.Style>
<Style TargetType="{x:Type GroupBox}">
<Setter Property="Background" Value="white"/>
</Style>
</GroupBox.Style>
<Label Content="dsfdsfdsf" Foreground="Black" />
</GroupBox>
</Grid>

By setting
<Style TargetType="{x:Type GroupBox}">
<Setter Property="Background" Value="White"/>
</Style>
you will set the background of all GroupBox controls within your GroupBox and the GroupBox itself to white.
So if you want to set/override the Background of all Labels within your GroupBox just add an additional Style to your GroupBox targeting Label
<Style TargetType="{x:Type Label}">
<Setter Property="Background" Value="White"/>
</Style>
If you want to reset the style property of your Label just add an empty style definition to your GroupBox
<Style TargetType="{x:Type Label}"/>
The next approach is used on your on risk :)
If you only want to reset the background color, you can do this trick/hack to reset:
<Style TargetType="{x:Type Label}">
<Setter Property="Background" Value="{Binding Background.DefaultValue, RelativeSource={RelativeSource Self}}" />
<Setter Property="Foreground" Value="Black" />
</Style>
Hint: Instead of Background.DefaultValue you can also write Background.ABC the main thing here is that the binding goes wrong.

Ability to Select Anywhere on Expander to Expand

I am working in WPF C# and noticed that my expander will expand and collapse when when I click on the button or header (words) of the expander but will not expand when I click on the part of the expander beside the header.
The weird part is that it will collapse the expander when clicking on the same spot beside the expander.
So does anyone know how to allow the entire expander to be clicked on to expand and collapse it?
Any help is greatly appreciated!
<Expander ExpandDirection="Down" Width="Auto" Padding="4" Expanded="Expander_Expanded">
<Expander.Style>
<Style TargetType="Expander">
<!--<Setter Property="IsExpanded" Value="{Binding XPath=#Name, Converter={StaticResource ExpandConverter}}" />-->
<Setter Property="IsExpanded" Value="{Binding XPath=#Expand}" />
<Setter Property="Header">
<Setter.Value>
<MultiBinding Converter="{StaticResource NameConverter}">
<Binding XPath="#Name" />
</MultiBinding>
</Setter.Value>
</Setter>
<Setter Property="FontWeight" Value="Bold" />
<Style.Triggers>
<DataTrigger Binding="{Binding IsExpanded,RelativeSource={RelativeSource Self}}" Value="True">
</DataTrigger>
</Style.Triggers>
</Style>
</Expander.Style>
<ListBox Name="itemsList"
ItemsSource="{Binding XPath=UpgradeAction}"
ItemTemplate="{StaticResource dtListItemTemplate}"
SelectionChanged="listItems_SelectionChanged"
Style="{StaticResource styleListBoxUpgradeAction}"
ItemContainerStyle="{StaticResource styleListBoxItemUpgradeAction}"
MouseDoubleClick="itemsList_MouseDoubleClick">
</ListBox>
</Expander>

Have a look at the controltemplate perhaps? You could also use a click event and see if the mouse is on the header part and make it a reusable Behavior.

The problem was that the width of the expander was not set, so it was auto. Therefore it worked when it was closing because the width, when opened, is set to the entire expander. However, it didn't work while collapsed because when collapsed, the expander width is only set to as far as the header goes. Thus, I changed the width to a fixed value and it allowed me to press anywhere on the top part of the expander to open and close it.

Display button tooltip on a label for wpf button

I have several WPF buttons on my Page and I want to display tooltips when the mouse is hovered over them.
But I want the tooltip to appear in a label that I have pplaced on my page so I want to show this label and set its text to something.
Whenever the mouse is moved away from the button I want the label to disappear again.
I can change the image of my buton by doin what I learned here: http://www.canofcode.co.uk/software/wpf-rollover-images/
but I cant figure out how to display this tooltip yet....

You can achieve that using DataTrigger on IsMouseOver property of button. This is what you are looking for i guess -
<StackPanel Orientation="Horizontal" VerticalAlignment="Center">
<Button x:Name="button1" Content="TestButton" Width="100" Height="50"/>
<Label x:Name="label1" Content="Tooltip Text">
<Label.Style>
<Style TargetType="Label">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=button1,
Path=IsMouseOver}"
Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Label.Style>
</Label>
</StackPanel>

Is there something equivalent to TemplateBinding outside of a ControlTemplate?

I'm new to the styling part of WPF. What I want to do is to get the value of an attached property in a setter, e.g.:
<Trigger Property="SomeProperty" Value="SomeValue">
<Setter Property="SomeProperty"
Value="(My attached property, let's say lcl:MyClass.MyString)"/>
</Trigger>
I know that you can get something to this effect using a {TemplateBinding lcl:MyClass.MyString} in a ControlTemplate. My question is: can you do this in a style, without using a ControlTemplate?

You can try to use:
<Setter Property="SomeProperty" Value="{Binding Path=(lcl:MyClass.MyString), RelativeSource={RelativeSource self}}"/>
if your attached property applies to the element as your style. If not, you can use RelativeSource or ElementName to find the appropriate element.
I am not sure how you have done that since your code lacks of details. Below code works:
<UserControl.Resources>
<Style x:Key="LabelStyle" TargetType="{x:Type Label}">
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Content"
Value="{Binding Path=(TestWebBrowser:AttachP.ValueEditorState), RelativeSource={RelativeSource self}}"/>
</Trigger>
</Style.Triggers>
</Style>
</UserControl.Resources>
<StackPanel>
<Label x:Name="label" TestWebBrowser:AttachP.ValueEditorState="HelloWorld" Style="{StaticResource LabelStyle}"/>
<Button Content="Disable Label" Click="Button_Click"/>
</StackPanel>
Button's click event handler will set Label's IsEnabled to false to trigger the trigger. And note that you have to use Path= with parenthesis in the binding.