Develop Reference

Display icon over select images in wpf listbox

I've looked at some related answers (Content of a Button Style appears only in one Button instance, and Images only showing in last ListBoxItem), but can't seem to get their answers to work in my example.
My app wpf stack is relatively complex.
I've a UserControl within another window. Within the UserControl, I've a ListBox with nested elements ListBox.ItemTemplate > DataTemplate > Border > Grid > StackPanel
Within the StackPanel is a TextBlock, followed by an Image and a StackPanel.ToolTip
I'm wanting to place an icon over the Image, so I've further obfuscated the image by putting it in a Grid, and adding a ViewBox accessed via a Control Template (as suggested in the above links), so that the ViewBox is centered on the image. Here's the Grid:
<Grid>
<Image RenderOptions.BitmapScalingMode="HighQuality"
Height="{Binding ElementName=_this, Path=ThumbSize.Height}"
>
<gif:ImageBehavior.AnimatedSource>
<MultiBinding Converter="{c:ImageConverter}">
<Binding Path="ThumbLocation" />
<Binding Path="FullName" />
</MultiBinding>
</gif:ImageBehavior.AnimatedSource>
</Image>
<Control Template="{StaticResource PlaySymbol}" Visibility="{Binding PlayVisible}" />
</Grid>
The ViewBox's ControlTemplate is in the UserControl.Resources up at the top
<ControlTemplate x:Key="PlaySymbol" TargetType="{x:Type Control}">
<Viewbox Stretch="Uniform"
RenderTransformOrigin="0.5,0.5"
Opacity="0.75"
x:Shared="False"
>
<Viewbox.RenderTransform>
<TransformGroup>
<ScaleTransform ScaleX="0.5" ScaleY="0.5"/>
</TransformGroup>
</Viewbox.RenderTransform>
<ContentControl Content="{StaticResource appbar_control_play}" />
</Viewbox>
</ControlTemplate>
The appbar_control_play is in the Resources directory in an Icons.xaml file.
<Canvas x:Key="appbar_control_play" Width="76" Height="76" Clip="F1 M 0,0L 76,0L 76,76L 0,76L 0,0">
<Path Width="20.5832" Height="31.6667" Canvas.Left="30.0833" Canvas.Top="22.1667" Stretch="Fill" Fill="{DynamicResource BlackBrush}" Data="F1 M 30.0833,22.1667L 50.6665,37.6043L 50.6665,38.7918L 30.0833,53.8333L 30.0833,22.1667 Z "/>
</Canvas>
The goal is to only display the icon for 'play' on movies. I've set the PlayVisible to return the proper visibility for movies, and not for other files. Yet, it is only displaying for the last movie. I've heard that this is the case for controls only able to have one parent. I've tried setting x:Shared="False" on the ViewBox, but to no avail.
The app works, but I've recently decided to add movies to the listing and want to display the play icon over their thumbnails, but not the other items. It seems simple on the outset, but I've yet to figure out what is needed.
Any help would be appreciated, otherwise I feel I may have to resort to overlaying the icon on the actual thumbnails of the movies.

It looks like the problem is not related to the Viewbox but the image resource appbar_control_play it references.
There is no need to add the Viewbox via a Control. Just add it directly to the DataTemplate.
Generally prefer a ContentControl over a templated Control if you wish to display content.
The x:Shared attribute is only required on a UIElement that is not part of a template but defined in a ResourceDictionary. For example, when you define the Viewbox in as a resource, you must set the x:Shared attribute to false. Otherwise it is only allowed to appear once in the visual tree.
In case the image resource is an image file, a proper DataTemplate could look as followed:
<DataTemplate>
<StackPanel>
<Grid>
<Image Source="path to image" />
<Image Source="path to overlay icon"
Stretch="UniformToFill"
Width="50"
Height="50" />
</Grid>
</StackPanel>
</DataTemplate>
In case the icon is a XAML resource like a Geometry or a Segoe MDL2 Assets font icon, the DataTemplate should look as followed:
App.xaml
<Application.Resources>
<Viewbox x:Key="PlayIcon" x:Shared="False">
<TextBlock FontFamily="Segoe MDL2 Assets"
Text="" />
</Viewbox>
<Viewbox x:Key="appbar_control_play"
x:Shared="False">
<Path Width="20.5832"
Height="31.6667"
Stretch="Fill"
Fill="{Binding RelativeSource={RelativeSource AncestroType=ContentControl}, Path=For4ground}"
Data="F1 M 30.0833,22.1667L 50.6665,37.6043L 50.6665,38.7918L 30.0833,53.8333L 30.0833,22.1667 Z " />
</Viewbox>
</Application.Resources>
MyControl.xaml
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<Grid>
<Image Source="path to image" />
<ContentControl Content="{StaticResource appbar_control_play}"
Width="50"
Height="50"
Foreground="Pink" />
</Grid>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>

Not sure what's happening on your side but the following just works:
<Window x:Class="abc.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:system="clr-namespace:System;assembly=System.Runtime"
mc:Ignorable="d"
Title="Window1">
<Grid>
<ListBox>
<ListBox.ItemTemplate>
<DataTemplate>
<DataTemplate.Resources>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
</DataTemplate.Resources>
<Border Width="64" Height="64" BorderBrush="Red" BorderThickness="1">
<Grid>
<TextBlock Text="{Binding}"
HorizontalAlignment="Center"
VerticalAlignment="Center" />
<Rectangle Fill="DeepSkyBlue"
HorizontalAlignment="Right"
VerticalAlignment="Bottom"
Margin="2"
Width="16"
Height="16"
Visibility="{Binding Converter={StaticResource BooleanToVisibilityConverter}}"
x:Name="Button" />
</Grid>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
<system:Boolean>True</system:Boolean>
<system:Boolean>False</system:Boolean>
<system:Boolean>True</system:Boolean>
<system:Boolean>False</system:Boolean>
<system:Boolean>True</system:Boolean>
<system:Boolean>False</system:Boolean>
</ListBox>
</Grid>
</Window>

Add a Textblock inside a border with nested StackPanels, in code

I am trying to modify a TextBlock from a WPF code.
I have the following MainWindow XAML :
<Window x:Class="ChatServer.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:ChatServer"
mc:Ignorable="d"
ResizeMode="NoResize"
Title="Serveur de chat" Height="450" Width="800">
<Grid x:Name="Grille">
<DockPanel x:Name="DockP" LastChildFill="False">
<StackPanel Orientation="Horizontal" DockPanel.Dock="Top" VerticalAlignment="Center" Margin="5,5,0,0" >
<Border BorderThickness="1" BorderBrush="Blue" DockPanel.Dock="Left" Height="20" Width="380">
<TextBlock HorizontalAlignment="Center" >Statut du Serveur</TextBlock>
</Border>
<Border BorderThickness="1" BorderBrush="Blue" DockPanel.Dock="Right" Height="20" Width="380">
<TextBlock HorizontalAlignment="Center">Gestion des Clients</TextBlock>
</Border>
</StackPanel>
<StackPanel x:Name="DataZ" Orientation="Horizontal" DockPanel.Dock="Top" VerticalAlignment="Center" Margin="5,0,0,0" >
<StackPanel x:Name="Server" Orientation="Vertical" DockPanel.Dock="Top" VerticalAlignment="Center" Margin="0,0,0,0">
<Border BorderThickness="1" BorderBrush="Blue" DockPanel.Dock="Left" Width="380">
<TextBox Name="ServerStatus" HorizontalAlignment="Center" VerticalAlignment="Top" Height="30" Width="380" Text="Serveur éteint" Background="#FFB0B0" TextAlignment="Center"/>
</Border>
<Border x:Name="ServerBorder" BorderThickness="1" BorderBrush="Blue" DockPanel.Dock="Left" Height="350" Width="380">
<StackPanel x:Name="SP" Orientation="Vertical" DockPanel.Dock="Top" Margin="0,0,0,0">
<StackPanel Orientation="Horizontal" DockPanel.Dock="Top" Margin="0,0,0,0">
<Button Content="Démarrer" Height="20" Width="60" VerticalAlignment="Top" HorizontalAlignment="Left" Margin="10,10,10,10" Click="Demarre"/>
<Button Content="Arrêter" Height="20" Width="60" VerticalAlignment="Top" HorizontalAlignment="Right" Margin="10,10,10,10" Click="Arrete"/>
</StackPanel>
<Border x:Name="LogBorder" BorderThickness="3" BorderBrush="Green" DockPanel.Dock="Left" Height="300" Margin="3,3,3,3">
</Border>
</StackPanel>
</Border>
I would like to add a Textblock inside the "LogBorder" Border (the last one). Here is the code (not working) :
public MainWindow()
{
InitializeComponent();
void CreateServerLogText()
{
TextBlock ServerLog = new TextBlock();
// <Border x:Name="LogBorder" BorderThickness="3" BorderBrush="Green" DockPanel.Dock="Left" Height="300" Margin="3,3,3,3">
// <TextBlock x:Name="ServerLog" Text="Logs du serveur" TextWrapping="Wrap"/>
// </ Border >
Grille.LogBorder.Child = ServerLog; // NOT WORKING
// Grille.DockP.DataZ.Server.ServerBorder.SP.LogBorder.Children.Add(ServerLog); // NOT WORKING
}
CreateServerLogText();
}
How do you "navigate" inside the XAML tree to add or modify content inside StackPanel and Border ?

The LogBorder field is a direct member of MainWindow. Even if the border is nested inside another control in xaml, the field itself is not nested. Simply remove Grille. to make it work. You must differentiate between the static C# code where the field is declared, and the nested data structure created dynamically at runtime by WPF based on the xaml code.
This test code works for me:
public MainWindow()
{
InitializeComponent();
TextBlock ServerLog = new TextBlock { Text = "Hello world" };
LogBorder.Child = ServerLog;
}
Side note: "not working" is not an adequate description of the problem. "Working" or "not working" requires the code to compile and to run. Only when it runs, you can test whether it is working as expected or not.
In your case, the code is not compiling. You get the compiler error
Error CS1061 'Grid' does not contain a definition for 'LogBorder' and no accessible extension method 'LogBorder' accepting a first argument of type 'Grid' could be found (are you missing a using directive or an assembly reference?)
The error tells you that the Grid (Grille) does not contain the expected LogBorder field. Which is correct since it is contained in MainWindow.

It is something like
TextBlock CreateServerLogText()
{
TextBlock ServerLog = new TextBlock();
LogBorder.Child = ServerLog;
return ServerLog;
}
TextBlock ServerLog = CreateServerLogText();

HeaderedContentControl header template not being used

I'm fairly new to WPF and am working with some legacy code, not sure how to use the HeaderedContentControl Header. I'd like to put in a StackPanel and customize the look of a header, just not sure how to do that.
Could someone give me some guidance on what to do next?
I have this xaml and the HeaderTemplate is never used.
<UserControl x:Class="PEC.Admin.WindowsControls.Program.Views.ProgramProductEnrichmentColorsView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:commonControls="clr-namespace:ManagerConsole.Common.Controls;assembly=ManagerConsole.Common.Controls"
xmlns:program="clr-namespace:PEC.Admin.ViewModel.Program;assembly=PEC.Admin.ViewModel.Program"
mc:Ignorable="d"
d:DesignWidth="300"
d:DataContext="{d:DesignInstance program:ProgramProductEnrichmentColorsViewModel}">
<commonControls:ExpanderPanel IsExpanded="{Binding Path=IsExpanded,Mode=TwoWay}">
<HeaderedContentControl.HeaderTemplate> <!-- this never gets used... -->
<DataTemplate>
<StackPanel>
<Label Content="{Binding Path=Header}"></Label>
</StackPanel>
</DataTemplate>
</HeaderedContentControl.HeaderTemplate>
<StackPanel HorizontalAlignment="Stretch"
VerticalAlignment="Top"
Width="Auto"
Margin="3"
Background="White">
<TextBlock Text="Source Type:"
Margin="0,5,0,0" />
<TextBox IsReadOnly="True"
IsTabStop="False"
Background="LightGray"
BorderThickness="0"
Text="{Binding Path=SourceTypeName, Mode=OneTime}" />
</StackPanel>
</commonControls:ExpanderPanel>
</UserControl>

HeaderTemplate is applied. To verify it - set a background to the Label in HeaderTemplate.
HeaderTemplate doesn't display anything though, because binding is incorrect. Template is applied to the data set in Header property, which currently has null value.
So change code as in the example below (I tried with Expander, hopefully it will work for custom commonControls:ExpanderPanel):
<Expander IsExpanded="{Binding Path=IsExpanded, Mode=TwoWay}"
Header="{Binding ComplexObject}">
<HeaderedContentControl.HeaderTemplate>
<DataTemplate>
<StackPanel>
<Label Background="Green" Content="{Binding PropertyOfTheObject}"/>
</StackPanel>
</DataTemplate>
</HeaderedContentControl.HeaderTemplate>
</Expander>
Header is a dependency property and can be set via Binding. Header becomes a source for bindings in a HeaderTemplate. Or it can be some constant (Header="Click to expand"), resource (Header="{StaticResource ExpandTitle}") or complex content, e.g.:
<Expander.Header>
<TextBlock Text="Click to expand"/>
</Expander.Header>

Windows Store App - XAML UI element not visible in C# code

I have the following XAML code and the only element available in the C# code behind are the Grid and the FlipView. How can I make the ScrollViewer, Image or the Viewbox visibile in the code?
XAML:
<Grid x:Name="gridViewPages">
<FlipView x:Name="FlipView1" Loaded="FlipView1_Loaded" Style="{StaticResource FlipViewPreviewIndicator}" Tapped="FlipView1_Tapped">
<FlipView.ItemTemplate>
<DataTemplate>
<ScrollViewer x:Name="pagesScrollViewer" ZoomMode="Enabled"
HorizontalAlignment="Center"
VerticalAlignment="Center"
HorizontalScrollBarVisibility="Hidden"
VerticalScrollBarVisibility="Hidden"
MinZoomFactor="1.0"
MaxZoomFactor="3.0"
Margin="0"
Width="1500" DoubleTapped="PagesScrollViewer_DoubleTapped">
<Viewbox x:Name="pagesViewbox">
<Image Source="{Binding}"
Height="730"
x:Name="pageImage" Stretch="Uniform" Loaded="MainImage_Loaded"/>
</Viewbox>
</ScrollViewer>
</DataTemplate>
</FlipView.ItemTemplate>
</FlipView>
</Grid>
The flipview is customized and contains also a listview defined in which is not visible in the code too...:
<Page.Resources>
...
<ListView x:Name="pagesPreview" HorizontalAlignment="Center" Height="100" VerticalAlignment="Bottom" Width="Auto"
ItemsSource="{TemplateBinding ItemsSource}"
SelectedItem="{Binding SelectedItem, Mode=TwoWay, RelativeSource={RelativeSource Mode=TemplatedParent}}"
ScrollViewer.HorizontalScrollBarVisibility="Auto"
ScrollViewer.VerticalScrollBarVisibility="Disabled"
ScrollViewer.HorizontalScrollMode="Enabled"
ScrollViewer.VerticalScrollMode="Disabled"
Background="AliceBlue"
Opacity="1"
SelectionChanged="pagesPreview_SelectionChanged"
Visibility="Visible">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Center" VerticalAlignment="Center">
<Image Source="{Binding}" Stretch="UniformToFill"/>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
...
</Page.Resources>

See the basic concept of the flipview is to have multiple pages to have a flip effect. So whatever the Data template contains is repeated multiple times. So if you want the x:Name to come up then you wont have any success.
There are two ways As per my knowledge :
VisualTreeHelper -> for a better detail of it go through this link
Get elements from data template
you can manually iterate over the flipview elements and track down the children of the flipview. Try that in debug mode you'll get a fair idea of what comes after what. Just keep track of the element at which selected index position you want modified
Thanks.

ContentPresenter in UserControl

I'm new to WPF and I'm trying to create an UserControl which will have some nested content.
<my:InformationBox Header="General Information" Width="280">
<StackPanel>
<Label>Label1</Label>
<Label>Label2</Label>
</StackPanel>
</my:InformationBox>
As you can see I want to put a StackPanel into it. As I read some articles I am supposed to add ContentPresenter to my UserControl, so I did, but I cannot find what should be binded to it's Content property.
Here is my UserControl code
<UserControl x:Class="ITMAN.InformationBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="200" d:DesignWidth="280" Name="infoBox" Loaded="infoBox_Loaded">
<StackPanel Width="{Binding ElementName=infoBox, Path=Width}" HorizontalAlignment="Stretch">
<Label Content="{Binding ElementName=infoBox, Path=Header}" />
<Border BorderThickness="0,1,0,0" Padding="10 5" Margin="5 0 5 10" BorderBrush="#B4CEDE">
<StackPanel>
<ContentPresenter Content="{Binding Content}" />
<Label Content="End" />
</StackPanel>
</Border>
</StackPanel>
</UserControl>
I've tried many combinations from various articles, but I cannot find any working example of what I want to achieve.
Similiar question was asked earlier by another user, but given there answers didn't help me: Does anyone have a simple example of a UserControl with a single ContentPresenter?

ContentPresenter is kind of a magic control. If you don't supply anything to it, it will automatically set the Content, ContentTemplate and ContentTemplateSelector property with a TemplateBinding to the TemplatedParent. Which means, you don't need to supply anything to it, just
<ContentPresenter/>
in your UserControl, and it should automatically use the corresponding properties found in your UserControl.
Also remember that a binding like {Binding Content} always referes to your DataContext, which i guess is not what you wanted.

I solved this problem by applaying custom style to GroupBox. I've created Syle in ResourceDictionary, which looks as follows
<Style x:Key="InformationBoxStyle" TargetType="GroupBox">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="GroupBox">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Label>
<ContentPresenter Margin="4" ContentSource="Header"
RecognizesAccessKey="True" />
</Label>
<Border Grid.Row="1" BorderThickness="0,1,0,0" Padding="10 5"
Margin="5 0 5 10" BorderBrush="#B4CEDE">
<StackPanel>
<ContentPresenter />
</StackPanel>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
And applied this style to GroupBox
<GroupBox Header="General Information" Width="280" Style="{StaticResource InformationBoxStyle}">
<StackPanel>
<Label>Label1</Label>
<Label>Label2</Label>
</StackPanel>
</GroupBox>
This code works as expected
You may also refer to this great article, which shows different options to achieve it:
http://www.codeproject.com/Articles/82464/How-to-Embed-Arbitrary-Content-in-a-WPF-Control
It also describes why ContentPresenter doesn't work in my code.

You need to create a dependency property on your UserControl code behind such as InnerContent.
public object InnerContent
{
get { return GetValue(InnerContentProperty); }
set { SetValue(InnerContentProperty, value); }
}
public static readonly DependencyProperty InnerContentProperty =
DependencyProperty.Register("InnerContent", typeof(object), typeof(ConfirmationControl), new PropertyMetadata(null));
Then you need to bind to that InnerContent on the XAML side of that UserControl.
<ContentControl Content="{Binding InnerContent, ElementName=userControl}" />
Then when you use it instead of placing content in the UserControl directly and overwriting the existing content just add it to the InnerContent portion.
<UserControls:InformationBox>
<UserControls:InformationBox.InnerContent>
<TextBlock Text="I'm in the InnerContent" />
</UserControls:InformationBox.InnerContent>
</UserControls:InformationBox>
Otherwise using a Template or Style is just as good but if you're wanting to package up a UserControl for use without forcing anyone to also reference a style or template this is probably one of your better options.