Develop Reference

How to 'Disable' a WPF UserControl?

I have a UserControl, and I need to change its appearance when 'IsEnabled' is false. I know this is pretty basic WPF styling, but I can't seem to put the pieces together. I assume that I need to create a Style, and add a trigger for "Property="IsEnabled" Value="False". But where do I put the Style definition? (<UserControl.Resources>?) How do I apply it? ... in the UserControl or in the Parent window? Does my trigger need to be inside a Setter element? Does the style need to be applied to the UserControl or to its children? I don't know what other questions I need to ask!
If you feel this is a duplicate of another question, please direct me to it.
If you know of a good, simple tutorial on WPF styling that would answer my questions, I would be very grateful to hear of it.
My code looks like this:
<UserControl x:Class="UserControls.UCDemo"
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:local="clr-namespace:UserControls"
mc:Ignorable="d"
d:DesignHeight="240" d:DesignWidth="200">
<UserControl.Resources>
</UserControl.Resources>
<Grid Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="5*" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="{Binding BG}" >
<Ellipse Grid.Row="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="5" Fill="DeepSkyBlue" />
</Grid>
<Grid Grid.Row="1" Background="Tomato" />
</Grid>
<uc:UCDemo x:Name="Demo" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="300,100,0,0" Width="80" Height="100" Style="{StaticResource uc:DemoStyle}"
Visibility="{Binding LightVisible, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Converter={StaticResource BooleanToVisibilityConverter}}" />
Thank you for your help!

It depends on how exactly the appearance should change when IsEnabled is false.
A simple Style with a Trigger could be assigned directly to the UserControl's Style property. The one below just sets the Opacity to 0.5.
<UserControl ...>
<UserControl.Style>
<Style TargetType="UserControl">
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Opacity" Value="0.5"/>
</Trigger>
</Style.Triggers>
</Style>
</UserControl.Style>
<Grid Background="Transparent">
...
</Grid>
</UserControl>

I'm not sure I get what your question is. However in order to change the IsEnabled property of a control, depending on an other controls is:
Let's suppose that the control which its IsEnabled must be changed, is A and the control which A is depends on, is B.
First, choose a name for B: x:Name = "AccessCheckBox".
Then Write a binding like this for control B:
< ... IsEnabled = {Binding ElementName = "AccessCheckBox", Path="IsChecked".../>
Done. I hope I got what you mean.

Hiding/Showing a UserControl WPF

I am building a WPF MVVM application.
What I have:
I have a ShellWindow which looks like this:
It is composed by 2 rows:
1: the hamburger menu (not important) with Height="*"
2: the console with Height="100"
The console is a UserControl:
<UserControl
//namespaces>
<Grid Name="LoggingGrid" Background="Black">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock Grid.Row="0" Margin="{StaticResource SmallLeftMargin}">
<Button
x:Name="CollapseBtn"
Width="25"
Height="25"
Click="CollapseBtn_Click"
Content="▲">
<Button.Template>
<ControlTemplate TargetType="{x:Type Button}">
<Grid>
<Ellipse Fill="White" />
<ContentPresenter
HorizontalAlignment="Center"
VerticalAlignment="Center"
Content="{TemplateBinding Content}" />
</Grid>
</ControlTemplate>
</Button.Template>
</Button>
<StackPanel Margin="5,0,0,0" Orientation="Horizontal">
<Image
Height="25"
Source="/Images/console-icon.png"
Visibility="Visible" />
<Label
Content="Console"
FontSize="16"
Foreground="White" />
</StackPanel>
</TextBlock>
<Border Grid.Row="1">
<ListView
x:Name="LoggingList"
Margin="5"
Background="Black"
BorderThickness="0"
Foreground="White"
ItemsSource="{Binding Logs, UpdateSourceTrigger=PropertyChanged}"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Auto" />
</Border>
</Grid>
</UserControl>
I have omitted the non-important things.
What I want to do:
Whenever the user clicks on the button, the console should collapse and look something like this:
The arrow is also changed.
How can I implement this? What is the best approach using MVVM?
What I have tried:
I have tried using a button click event handler in the code behind - CollapseBtn_Click, just to see what will happen:
private void CollapseBtn_Click(object sender, System.Windows.RoutedEventArgs e)
{
LoggingGrid.Visibility = System.Windows.Visibility.Hidden;
}
Apparently it removes the user control and leaves a white background where it used to be.

Instead of setting the Visibility of the whole LoggingGrid to Hidden, you should set the Visibility of the LoggingList to Collapsed. (For the difference between Hidden and Collapsed, see here: Difference between Visibility.Collapsed and Visibility.Hidden).
Depending on your layout in the ShellWindow you probably have to adjust your row height configuration in the UserControl such that the collapsed LoggingGrid leads to a row with a height of zero.
Regarding MVVM the best approach would be to bind the Button to a bool property ConsoleVisible on your ViewModel such that clicking the button toggles the property between true and false. The styling of the button can be bound to the same property. For the LoggingList Visibility you could use a Binding with a BooleanToVisibilityConverter on the same property.

WPF: How to access element in ResourceDictionary code behind

In my application I have a control which renders a number of blocks on a timeline view (like a calendar). One can provide a template for the blocks by giving the timeline an appropriate DataTemplate.
I would like to separate the block DataTemplate from the main timeline view, putting the block into its own XAML. As such, I've created a XAML for the Block (called Block.xaml) and wrapped the DataTemplate inside a ResourceDictionary, inside this XAML.
I've added a code behind to the XAML (called Block.xaml.cs) in which I need to access some of the elements in the block. The issue is that ResourceDictionaries seem to hide the elements from the codebehind such that I can't access them. I can't use a UserControl instead - this seems to not work.
How can I access the elements of the Block DataTemplate from the code behind?
Many thanks in advance for your help.
Block.xaml:
<ResourceDictionary x:Class="Project.Windows.MainInterface.TimelinePanel.Block" 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:local="clr-namespace:Project.Windows.MainInterface.TimelinePanel" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" xmlns:converters="clr-namespace:Project.Converters" >
<DataTemplate x:Key="ItemBlockTemplate">
<Grid Name="BlockParent" Width="Auto" Height="Auto" MinHeight="50" ClipToBounds="True" SizeChanged="BlockParent_OnSizeChanged">
<Border Panel.ZIndex="3" BorderBrush="{DynamicResource BackgroundGreyLight}" BorderThickness="1" CornerRadius="1" />
<Grid Margin="1" Background="{DynamicResource BlockBackgroundGradient}" d:LayoutOverrides="Width">
<TextBlock x:Name="blockName" Height="20" Margin="4,0,4,0" Padding="3" VerticalAlignment="Top" Panel.ZIndex="3" FontSize="10" Foreground="{DynamicResource TextLight}" Text="{Binding blockName}" TextTrimming="CharacterEllipsis" Visibility="Visible" />
<TextBlock x:Name="Duration" Margin="0,2,4,2" Padding="0,0,3,0" HorizontalAlignment="Right" VerticalAlignment="Bottom" Panel.ZIndex="5" FontSize="10" Foreground="{DynamicResource TextLight}" Text="{Binding FormattedDuration}" ToolTip="{Binding Duration}" />
<Grid Background="#FF0FA8FF" Opacity="0.7" />
</Grid>
</Grid>
</DataTemplate>
Snippet of the Timeline in the main interface:
...
<timeLineTool:TimeLineControl x:Name="Timeline" Height="50" MinWidth="50" Margin="0,0,12,0" HorizontalAlignment="Left" VerticalAlignment="Top" Items="{Binding Timeline}" SnapsToDevicePixels="True" UnitSize="{Binding UnitSize}" UseLayoutRounding="True">
<timeLineTool:TimeLineControl.ItemTemplate>
<DataTemplate DataType="{x:Type local:BlockItemViewModel}">
<ContentControl>
<ContentPresenter Margin="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Content="{Binding}" ContentTemplate="{StaticResource ItemBlockTemplate}" />
</ContentControl>
</DataTemplate>
</timeLineTool:TimeLineControl.ItemTemplate>
</timeLineTool:TimeLineControl>
...
...If I could use a UserControl instead of a ResourceDictionary for my Block, this would solve the problem, as all elements are automatically publicly available in the code behind for usercontrols.

Sample XAML:
<Window.Resources>
<ControlTemplate x:Key="ResourceName" TargetType="{x:Type Label}">
<Label Foreground="White" Content="{iconPacks:PackIconFontAwesome plug,Height=40,Width=40}"/>
</ControlTemplate>
</Window.Resources>
Code behind
ControlTemplate Dictionary:
private Dictionary<string, ControlTemplate> collection
{
get
{
Dictionary<string, ControlTemplate> controlTemplates = new Dictionary<string, ControlTemplate>();
controlTemplates.Add("ResourceName", FindResource("ResourceName") as ControlTemplate);
return controlTemplates;
}
}
Use ControlTemplate:
Label LBDisConnect = new Label();
LBDisConnect.Template = collection["ResourceName"];
LoginInfo.Children.Add(LBDisConnect);

WPF Expander overlay used in ItemsControl

I've been searching for some time but all solution I find only tackle parts of my issue.
I'd like to have an ItemsControl with each item containing an Expander. On expanding, the Expander's content should be shown as an overlay overlapping the other items in the ItemsControl and not moving them down.
The following XAML-Code does exactly as supposed to with one big issue: The Expander's content does not overlap the other items but is hidden behind them. I suppose this is due to the ZIndex as the following items in the ItemsControl are added after the Expander's content.
I managed to set one single Expander's ZIndex to 99 using style triggers but this seems to be a too complicated and error-prone solution. Any thoughts?
<Window x:Class="WpfTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow"
Height="350"
Width="525">
<Window.Resources>
<x:Array x:Key="items"
Type="sys:String"
xmlns:sys="clr-namespace:System;assembly=mscorlib">
<sys:String>One</sys:String>
<sys:String>Two</sys:String>
<sys:String>Three</sys:String>
<sys:String>Four</sys:String>
</x:Array>
<DataTemplate x:Key="template">
<Grid Background="Red" Margin="0,0,0,10">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBlock Text="{Binding}" />
<Canvas Height="25" Grid.Row="1">
<Expander ExpandDirection="Down" Header="Header" Grid.Row="1">
<Expander.Content>
<TextBlock Height="80" Text="Content" Background="Yellow" />
</Expander.Content>
</Expander>
</Canvas>
</Grid>
</DataTemplate>
</Window.Resources>
<Grid>
<ScrollViewer>
<ItemsControl ItemsSource="{StaticResource items}"
ItemTemplate="{StaticResource template}"
HorizontalContentAlignment="Stretch">
</ItemsControl>
</ScrollViewer>
</Grid>
</Window>

It's going to be tricky to achieve this in the way you are attempting it. The problem is the nested structure -- since each Canvas is nested inside a Grid, you won't be able to control its z-index relative to other Canvas element. To illustrate this, here is a schematic of the visual tree created by your current markup:
<StackPanel> <!-- items panel -->
<ContentPresenter> <!-- item wrapper -->
<Grid>
<Canvas>
</Canvas>
</Grid>
</ContentPresenter>
<ContentPresenter> <!-- item wrapper -->
<Grid>
<Canvas>
</Canvas>
</Grid>
</ContentPresenter>
</StackPanel>
With reference to the above, your goal will be to have the Canvas elements appear in front of the siblings of its parent ContentPresenter. This is impossible in this hierarchy, because ZIndex only applies relative to siblings of the same parent element. Now, there might be ways you could massage the above into a flat structure so that you could then apply ZIndex your expanded content as needed.
However, I think an easier and more natural approach would be to use Popup elements for the expanded content. A Popup is a framework primitive that is located outside of the visual tree, and will always sit on top of your other content. You can use a ToggleButton or something similar to create the "expand" effect. For example:
<StackPanel Grid.Row="1">
<ToggleButton x:Name="PopupToggle" Content="Expand" />
<Popup IsOpen="{Binding IsChecked,ElementName=PopupToggle}">
<TextBlock Height="80" Text="Content" Background="Yellow" />
</Popup>
</StackPanel>

Creating a button Template

I'm trying to create a template for a button that I can use over and over again on a form.
The Button, I want it to contain a Grid with two rows and a custom piece of text within the bottom row.
This is what I've got so far, but I don't think it's right because I want to set the text from within the button element.
<ControlTemplate TargetType="Control">
<Grid Width="444">
<Grid.RowDefinitions>
<RowDefinition Height="51" />
<RowDefinition Height="36" />
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="#286c97"></Grid>
<Grid Grid.Row="1" Background="#5898c0">
<TextBlock Grid.Row="1" FontFamily="Segoe UI" FontSize="12" Text="{TemplateBinding Content}" />
</Grid>
</Grid>
</ControlTemplate>
Then to call the template I was hoping I could go:
<Button Content="This is the text" />
But sadly this doesn't work. Is there some other template that I'm supposed to be using to pass the text value to it?

To make it work, there is a control called ContentPresenter. Place that inside your template wherever you want it to be. But remember, that it could be anything, a text, an image or a bunch of other controls, and your Button nor your ControlTemplate, should not care about what it is.
ControlTemplate TargetType="Control">
<Grid Width="444">
<Grid.RowDefinitions>
<RowDefinition Height="51" />
<RowDefinition Height="36" />
</Grid.RowDefinitions>
<Grid Grid.Row="0" Background="#286c97"></Grid>
<Grid Grid.Row="1" Background="#5898c0">
<ContentPresenter/>
</Grid>
</Grid>
</ControlTemplate>
The ContentPresenter, when used inside a ContentControl, like the button, automatically attaches to the Content, ContentTemplate and ContentTemplateSelector properties of the templated parent.
Now if you want to display more than just Text, or want to customize the text more, just pass a DataTemplate as your ContentTemplate directly to the specific button.
<DataTemplate x:Key="myButtonContentTemplate">
<TextBlock FontSize="18" Text="{Binding}"/>
</DataTemplate>
<Button ContentTemplate="{StaticResource myButtonContentTemplate}"/>