Develop Reference

WPF ComboBoxItem not showing until mouseover

I have a ComboBox with unbound items as shown in the XAML below. When the window containing this ComboBox opens, the ComboBox appears as if no ComboBoxItem is selected (even though SelectedIndex = 0) until the ComboBox or any other input control in the window is moused over. This mouseover seems to trigger an event causing the ComboBox to redraw/refresh, revealing the selection.
<Style x:Key="LineStyle" TargetType="Rectangle">
<Setter Property="Fill" Value="Black"/>
<Setter Property="Height" Value="3"/>
<Setter Property="Canvas.Top" Value="4"/>
</Style>
<ComboBox VerticalAlignment="Top" SelectedIndex="0">
<ComboBoxItem ToolTip="Solid" HorizontalAlignment="Center">
<Canvas Width="69" Height="11">
<Rectangle Style="{StaticResource LineStyle}" Width="69" Canvas.Left="0" />
</Canvas>
</ComboBoxItem>
<ComboBoxItem ToolTip="Dash" HorizontalAlignment="Center">
<Canvas Width="69" Height="11">
<Rectangle Style="{StaticResource LineStyle}" Width="11" Canvas.Left="0" />
<Rectangle Style="{StaticResource LineStyle}" Width="11" Canvas.Left="19" />
<Rectangle Style="{StaticResource LineStyle}" Width="11" Canvas.Left="38" />
<Rectangle Style="{StaticResource LineStyle}" Width="11" Canvas.Left="57" />
</Canvas>
</ComboBoxItem>
</ComboBox>
I had this exact same problem previously with a ComboBox with unbound items consisting of a StackPanel containing an Image and TextBlock. The workaround there was to bind the items rather than "hardcode" them in XAML, but that is not an option now. Is there an XAML solution to this blank ComboBox problem?
If I instead just use simple text-based ComboBoxItem like:
<ComboBoxItem Content="Solid" HorizontalAlignment="Center"/>
everything works fine. I am using the default ComboBox template in Visual Studio.

StackPanel Collapsed and Visible on Button Click

I am trying to show one collapsed stackpanel on button click, but I'm having problems so I tried reverse my thoughts and I was able to collapse an visible stackpanel. But unfortunately I was unable to implement the behavior I want, show an collapsed stack panel on button click. To the code :D
XAML
<Button x:Name="sentButton" Content="Add Friend" Style="{DynamicResource FlatButtonStyle}" Margin="493,0,0,0" HorizontalAlignment="Left" Width="106"/>
<StackPanel Style="{DynamicResource stackCollapsed}" Visibility="Collapsed">
<Label Content="Invite Friends" FontWeight="Bold" Margin="0,0,477,0" Height="32" />
<StackPanel Orientation="Horizontal" Margin="26,0,0,0">
<Label Content="Enter your friend's email" Width="222" Height="25" />
<TextBox Text="{Binding Email, UpdateSourceTrigger=PropertyChanged}" Style="{DynamicResource MyTextBox}" x:Name="textBoxEmail" Width="298"/>
<Button x:Name="button1" Content="Send" Command="{Binding AddCommand}" Width="77" Style="{DynamicResource FlatButtonStyle}" Margin="20,0,0,0"/>
</StackPanel>
</StackPanel>
Styles
<!-- Style Collapsed-->
<Style x:Key="stackCollapsed" TargetType="StackPanel">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=sentButton,Path=IsPressed}" Value="true">
<Setter Property="StackPanel.Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>

Instead of Button use ToggleButton and bind StackPanel.Visibility to ToggleButton.IsChecked property via BooleanToVisibilityConverter converter
<ToggleButton x:Name="sentButton" Content="Add Friend" Margin="493,0,0,0" HorizontalAlignment="Left" Width="106"/>
<StackPanel Visibility="{Binding ElementName=sentButton, Path=IsChecked, Converter={StaticResource BooleanToVisibilityConverter}}">
<Label Content="Invite Friends" FontWeight="Bold" Margin="0,0,477,0" Height="32" />
<StackPanel Orientation="Horizontal" Margin="26,0,0,0">
<Label Content="Enter your friend's email" Width="222" Height="25" />
<TextBox Text="{Binding Email, UpdateSourceTrigger=PropertyChanged}" x:Name="textBoxEmail" Width="298"/>
<Button x:Name="button1" Content="Send" Command="{Binding AddCommand}" Width="77" Margin="20,0,0,0"/>
</StackPanel>
</StackPanel>
where converter is defined as below
<Window.Resources>
<ResourceDictionary>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
</ResourceDictionary>
</Window.Resources>

The problem is the Visibility property in the <StackPanel> tab takes a higher precedence than anything set in a Style or Trigger, so the Trigger never gets applied. See the Dependency Property Precedence List for more details.
To fix your current solution, move the Visibliity property out of the <StackPanel> tag and into your Style, like this :
<Style x:Key="stackCollapsed" TargetType="StackPanel">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=sentButton,Path=IsPressed}" Value="true">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
<StackPanel Style="{DynamicResource stackCollapsed}">
...
</StackPanel>
That said, I would personally recommend something like a Toggle Button with the StackPanel.Visibility bound to the ToggleButton.IsChecked, like this answer suggests.

I solved set the Children to null
stackPanel.Children.Clear();
this work if you need to show / hide the panel the first time, it doesn't work if you need to do runtime

Simple as Stackpanel.Visibility = Visibility.Collapsed.

How to keep Popup in Application window wpf

I have been trying to have a popup whenever I press a button.
However. Lets say that I have a lot of text on that popup and then it can go over the application window bounds.
How I can I tell the popup to keep within the application window bounds in xaml code?
It would be great with some examples in xaml code on how to tell the Popup element to keep within the application
Thanks
Xaml code:
...
<ToggleButton Grid.Row="1" Grid.Column="1" Margin="0,4"
x:Name="Somethingname"
Height="30"
Template="{StaticResource ComboBoxToggleButton}"
Content="Hello man"/>
<Popup Grid.Row="1" Grid.Column="1" x:Name="PopupMe"
Style="{StaticResource PopupStyle}"
ClipToBounds="True">
<TreeView ItemsSource="{Binding SomeObservableCollection}"
Width="{Binding ElementName=DetaljerHjemmmelToggler, Path=ActualWidth}"
ItemTemplate="{StaticResource SomeTemplate}"
cal:Message.Attach="[Event SelectedItemChanged] = [Action TreeView_SelectedItem($this, $source)]">
</TreeView>
</Popup>
...
In ResourceDictionary XAML file:
<HierarchicalDataTemplate x:Key="SomeTemplate" ItemsSource="{Binding ChildrenCollection}">
<TextBlock Text="{Binding Path=TekstBlaaah}" Style="{StaticResource Label}"/>
</HierarchicalDataTemplate>
<Style TargetType="{x:Type Popup}" x:Key="PopupStyle">
<Setter Property="IsOpen" Value="{Binding ElementName=Somethingname, Path=IsChecked}"/>
<Setter Property="AllowsTransparency" Value="True"/>
<Setter Property="PlacementTarget" Value="{Binding ElementName=Somethingname}"/>
<Setter Property="PopupAnimation" Value="Slide"/>
<Setter Property="StaysOpen" Value="False" />
<Setter Property="Placement" Value="Bottom"/>
</Style>

Check it out:
Custom popup and windows in WPF the MVVM way
Sample is also available

Mah Apps Tile Animation

I would like to add the Live Tile effect to the tiles on my wpf app layout. I'm using the MahApps.Metro library for the visuals. Here is an example of one of the tiles that I have on the layout -
<Controls:Tile Height="110" Background="#9c6b50" Width="180" VerticalAlignment="Top" HorizontalAlignment="Right" Margin="0,105,33,0">
<Controls:Tile.Content>
<TextBlock Text="Setup Your Savings Account" TextWrapping="Wrap" Width="121" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Controls:Tile.Content>
</Controls:Tile>
I'd like the end product of the tile to switch between these two texts:
Setup your Savings account
Click here to Setup your savings account

The generally accepted way to do this is by binding the Text property. A binding would look like this:
<TextBlock Text="{Binding Path=TileText}" TextWrapping="Wrap" Width="121" HorizontalAlignment="Center" VerticalAlignment="Center"/>
What this does is bind the value of the TextBlock to a property called TileText on the DataContext of the control. You will need to look into DataContext and binding in WPF to understand this.
Once you have a class with the property:
public string TileText
{
get {...}
set {...}
}
And the class is set as the DataContext of the Tile control you can change the value of the TileText property and it will change the text of the TextBlock. This is a simple example of MVVM design and can be a good first step in understanding smart WPF design practices.
Cheers,
Eric

Try this!
<controls:Tile Height="110" Background="#9c6b50" Width="180" VerticalAlignment="Top" HorizontalAlignment="Right" Margin="0,105,33,0">
<controls:Tile.Style>
<Style TargetType="controls:Tile">
<Setter Property="Content">
<Setter.Value>
<TextBlock Text="Setup Your Savings Account" TextWrapping="Wrap" Width="121" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Content">
<Setter.Value>
<TextBlock Text="Click here to Setup Your Savings Account" TextWrapping="Wrap" Width="121" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Setter.Value>
</Setter>
</Trigger>
</Style.Triggers>
</Style>
</controls:Tile.Style>
</controls:Tile>

ListBox , DataTemplate and Triggers

i got a DataTemplate for a listboxitem and i want to create a triger , so when a user click an item the background will change and also the label
my code:
<Window.Resources>
<Style x:Key="RoundedItem" TargetType="ListBoxItem">
<EventSetter Event="MouseDoubleClick" Handler="listViewItem_MouseDoubleClick" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Border Name="ItemBorder" CornerRadius="10" BorderBrush="Black" BorderThickness="1" Margin="1" Background="Transparent">
<Label Name="ItemLabel" Foreground="Red" >
<ContentPresenter />
</Label>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter TargetName="ItemBorder" Property="Background" Value="DeepSkyBlue" />
<Setter TargetName="ItemLabel" Property="Foreground" Value="Orange" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<DataTemplate x:Key="TitleTemplate" DataType="models:Title" >
<StackPanel>
<Image Source="{Binding ThumbFilePath}" Width="50" HorizontalAlignment="Center"/>
<Label Content="{Binding Name}" HorizontalAlignment="Center" />
<TextBlock Text="{Binding Description}" HorizontalAlignment="Center" TextWrapping="Wrap" Padding="5,5,5,5"/>
</StackPanel>
</DataTemplate>
</Window.Resources>
What happend is that the TextBlock change his color and not the label..
anyone know why ?
Thanks.

The TextBlock inherits the Foreground definition from its parents in the visual tree. The Label, on the other hand, defines the Foreground in its default style.
Your approach is "non-WPF-like" - you shouldn't wrap the ContentPresenter in a Label control.
The right approach depends on whether you want all text in the item to change its Foreground, or just the label?
[In both cases, there's no apparent benefit to using a Label in the data template - so I'll assume that the label is changed to TextBlock.]
If the answer to the above question is that all text should be changed: in the ControlTemplate of the ListBoxItem, in the trigger for IsSelected, from the seccond setter remove TargetName="ItemLabel" so the final setter is:
<Setter Property="Foreground" Value="Orange" />
This will change the foreground of the item that will affect the foreground of both TextBlocks in the data template.
If you want to affect just one of the TextBlocks:
1. remove the setter for the foreground from the control template
2. add a trigger to your data template:
<DataTemplate>
<StackPanel>
<Image .../>
<TextBlock x:Name="Text01" ..../>
<TextBlock x:Name="Text02" ..../>
</StackPanel>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding IsSelected, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBoxItem}}}" Value="True">
<Setter TargetName="Text01" Property="Foreground" Value="Orange"/>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
Side note: if you have to use Label control in your data template, bind its Foreground property to the Foreground of the list box item, like so:
<Label Foreground="{Binding Foreground, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBoxItem}}}"....../>
If this doesn't help, it means that your list box item inherits its foreground, so use:
<Label Foreground="{Binding TextElement.Foreground, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBoxItem}}}"....../>

I want to tack on to this that I was experiencing a similar problem where I'd added a ListBox.ItemTemplate to my ListBox, and the styling then did not apply to the text anymore.
What I was doing was trying to display a list of languages (CultureInfo) for the user to select from, however I wanted the native names to display, not the English name. For some reason, not all languages have their native names capitalized in their CultureInfo, and NativeName is the only instance of their name, so I needed to apply a function to the CultureInfo.NativeName to capitalize the names myself. To accomplish this, I added the ItemTemplate with a Data Template inside, on which I applied a converter.
<ListBox IsSynchronizedWithCurrentItem="True" VerticalAlignment="Center" MinHeight="200" x:Name="cbLanguages"
ItemsSource="{Binding Path=SupportedCultures, Mode=OneWay, Source={StaticResource CultureResourcesDS}}"
FontSize="24" HorizontalAlignment="Stretch" Width="300" Margin="10"
Style="{DynamicResource ListBoxTemplate}" ItemContainerStyle="{DynamicResource ListBoxItemStyle}">
<ListBox.ItemTemplate>
<DataTemplate>
<Label Content="{Binding Converter={StaticResource NativeNameConverter}}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
After a while of searching, I came across XAMeLi's answer here, and changed the Label I'd put in the DataTemplate to a TextBox, and the ListBoxItemStyle I'd created worked again.
Basically, Labels and TextBoxes have different traits that can be exploited, or can cause annoying issues in this case. Here's a good explanation with some examples of the differences: http://joshsmithonwpf.wordpress.com/2007/07/04/differences-between-label-and-textblock/