Develop Reference

Flow icon view in WPF ListView

I am new to WPF and as a learning project I opted for a Windows Explorer like File Manager. In this project I want to display the the List view as a icon list that follows flow layout pattern. I tried the solutions given here: WPF: ListView with icons view?. But they are making my icons overlap each other. My icons are basically user controls that are loaded dynamically. This is my code for user control that represents a list view icon:
<UserControl x:Class="MVCP.FileItem"
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" Height="156.767" Width="161.279">
<Grid HorizontalAlignment="Center">
<Image HorizontalAlignment="Center" Height="100" Margin="10,10,10,0" VerticalAlignment="Top" Width="141" Source="fileflat.png"/>
<TextBlock HorizontalAlignment="Center" Margin="10,120,10,5" TextWrapping="Wrap" Text="<Filename>" VerticalAlignment="Center" Height="32" Width="141" FontSize="18" Foreground="White" TextAlignment="Center"/>
</Grid>
</UserControl>
And this is my ListView code:
<ListView x:Name="files" Background="#FF19174B" AllowDrop="True" ScrollViewer.HorizontalScrollBarVisibility="Disabled" PreviewMouseLeftButtonDown="files_PreviewMouseLeftButtonDown" MouseMove="files_MouseMove">
<local:FileItem/>
<local:FileItem/>
<local:FileItem/>
<local:FileItem/>
</ListView>
How can I arrange these user controls so that they can look like Windows Explorer icons?

#AbinMathew gave me a hint for using Panels. So, I changed my code like this and it worked. :)
<ListView x:Name="files" Background="#FF19174B" AllowDrop="True" ScrollViewer.HorizontalScrollBarVisibility="Disabled" PreviewMouseLeftButtonDown="files_PreviewMouseLeftButtonDown" MouseMove="files_MouseMove">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel/>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemTemplate>
<DataTemplate>
<DockPanel>
<local:FileItem/>
</DockPanel>
</DataTemplate>
</ListView.ItemTemplate>
<local:FileItem/>
<local:FileItem/>
<local:FileItem/>
<local:FileItem/>
</ListView>

Try adding any panel inside your ListView
<ListView x:Name="files" Background="#FF19174B" AllowDrop="True" ScrollViewer.HorizontalScrollBarVisibility="Disabled" PreviewMouseLeftButtonDown="files_PreviewMouseLeftButtonDown" MouseMove="files_MouseMove">
<StackPanel>
<local:FileItem/>
<local:FileItem/>
<local:FileItem/>
<local:FileItem/>
</StackPanel>
</ListView>

VirtualizingStackPanel isn't virtualizing

I have a virtualizing stack panel in my ItemsControl, in a scroll viewer. It doesn't seem to be virtualizing:
<Page
x:Class="IWalker.Views.FullTalkAsStripView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:IWalker.Views"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<ScrollViewer x:Name="theScrollViewer" VerticalScrollMode="Disabled" HorizontalScrollMode="Auto" VerticalScrollBarVisibility="Disabled" HorizontalScrollBarVisibility="Auto">
<ItemsControl x:Name="SlideStrip">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<VirtualizingStackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<local:PDFPageUserControl Margin="0 0 5 0" Height="{Binding Path=ActualHeight, ElementName=SlideStrip, Mode=OneWay}" ViewModel="{Binding}" RespectRenderingDimension="Vertical" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</ScrollViewer>
</Grid>
</Page>
The PDFPageUserControl prints out a little debug message when it is instantiated - and I always get one even when I get more than 50 items. The SlideStrip.ItemsSource is databound, so I don't think that is the problem (via ReactiveUI):
this.OneWayBind(ViewModel, x => x.Pages, y => y.SlideStrip.ItemsSource);
Where Pages is a ReactiveUI list.
What have I missed? Do I need to set IsVirtualizing to true? Where is that attached property in this case (since this isn't a ListBox)?
BTW, I will never have a large number of controls. The issue is that each control holds onto an image, and a large one at that (e.g. full screen on a high DPI display). All I really want to do is release the image when each PDF control is not visible, and re-load when it is. So there may be a better way to solve my problem.

WPF control for neural net visualization

I'm developing a Neural net, and for visualization I'm writing a UserControl in WPF.
The following code draws the neurons:
<UserControl x:Class="ExcelAddIn.LogView"
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="300" d:DesignWidth="300">
<UserControl.Resources>
<DataTemplate x:Key="ellipse">
<Grid Margin="0,10,0,0">
<Ellipse Width="50" Height="50" Fill="Red" Stroke="Black" StrokeThickness="2"/>
<TextBlock HorizontalAlignment="Center" Text="{Binding Input, StringFormat=N2}" TextAlignment="Center" Margin="0,10,0,0"/>
<TextBlock HorizontalAlignment="Center" Text="{Binding Output, StringFormat=N2}" TextAlignment="Center" Margin="0,22,0,0"/>
</Grid>
</DataTemplate>
<DataTemplate x:Key="panel">
<ScrollViewer VerticalScrollBarVisibility="Auto" Width="70" Margin="100,0,0,0">
<ItemsControl x:Name="Items" ItemsSource="{Binding Neurons}" ItemTemplate="{StaticResource ellipse}"/>
</ScrollViewer>
</DataTemplate>
</UserControl.Resources>
<Grid>
<ItemsControl x:Name="Panel" ItemsSource="{Binding Layers}" ItemTemplate="{StaticResource panel}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</Grid>
I would like to draw lines between the Neurons like this:
So for each neuron in the specific layer should have a line to each neuron in the next layer (drawing all the lines would made it harder to understand, so I didn't draw all the lines on the illustration). I would like to achieve this with binding. Is it possible? (I don't care if my existing code needs to be refactored, if that solves my problem.)
Note: I have a Weight object (a line would represent this weight). One Weight object has reference to two Neurons, a double, that is the weight between them and some other properties. And the weigths can be accessed from the datacontext of the usercontrol.
Thank you.

It seems the Nodes Editor example (from the another answer) should help. It is necessary to create instances of appropriate ViewModels (Node and Connector classes). Please note that Node coordinates must be filled before displaying (see the implementation of the NodesDataSource class).
Additional references to articles/libraries:
NetworkView: A WPF custom control for visualizing and editing networks, graphs and flow-charts.
Graphviz4Net library: provides WPF control that is capable of generating "nice looking" graph layouts).
Graph# library: a graph layout framework, it contains some layout algorithms and a GraphLayout control for WPF applications.

WPF UserControl not rendering. UserControl is instantiated using DataTemplates

I have a user control that I`m trying to show via data templates. Unfortunately, the control never shows. Here's the DataTemplate for it:
<DataTemplate x:Key="listViewTemplate">
<ctrls:SpecialControl/>
</DataTemplate>
If I put regular controls inside those DataTemplate tags, I can see them. My SpecialControl however, won't show. Here's the xaml file for my SpecialControl:
<UserControl x:Class="CustomControls.SpecialControl"
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">
<StackPanel>
<CheckBox Content="Hello World" />
<Button >
<TextBlock Text="Goodbye world"/>
</Button>
</StackPanel>
</UserControl>
For some reason, this control is invisible at run time. If I put them directly into the template, I'll see them. I know I could just do that, but I want to do something more complex with this class, using databinding, and custom behavior. I tried using Snoop, and I can see my SpecialControl in there somewhere, with a ContentPresenter that's not expandable: no sign of The checkbox or the button.
Edit:
Here is the View that is using the SpecialControl: I left out many of the templates I'm using, because I don't want this to be too crowded.
<UserControl x:Class="Tools.EditorWindow"
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:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase"
xmlns:ctrls="clr-namespace:CustomControls"
xmlns:local="clr-namespace:Tools"
mc:Ignorable="d"
x:Name="This">
<UserControl.Resources>
<!--More templates -->
<DataTemplate x:Key="groupBoxTemplate" >
<ctrls:SpecialGroupBox Header="{Binding Path=Title}" Margin="2" DockPanel.Dock="Top">
<ItemsControl ItemsSource="{Binding guiItemsList}" ItemTemplateSelector="{DynamicResource guiTemplateSelector}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel>
<!-- Set up the width of the individual items based on how many columns we are supposed to have and what the adjusted width of the wrapPanel is. This way the 4th item will be placed on the 2nd row if the ColumnCount is 3. -->
<WrapPanel.ItemWidth>
<MultiBinding Converter="{StaticResource itemWidthConverter}">
<Binding Path="ColumnCount"/>
<Binding Path="ActualWidth" RelativeSource="{RelativeSource Self}"/>
</MultiBinding>
</WrapPanel.ItemWidth>
</WrapPanel>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</ctrls:SpecialGroupBox>
</DataTemplate>
<DataTemplate x:Key="listViewTemplate">
<ctrls:SpecialControl/>
</DataTemplate>
<local:GuiTemplateSelector
... <!--More templates -->
GroupBoxTemplate="{StaticResource groupBoxTemplate}"
SpecialTemplate="{StaticResource listViewTemplate}"
x:Key="guiTemplateSelector"/>
</UserControl.Resources>
<DockPanel>
<ScrollViewer VerticalScrollBarVisibility="Auto" Grid.Row="1">
<StackPanel Name="rootPanel" DockPanel.Dock ="Top" Width="Auto" Height="Auto">
<ItemsControl ItemsSource="{Binding guiItemsList}" ItemTemplateSelector=" {StaticResource guiTemplateSelector}">
</ItemsControl>
</StackPanel>
</ScrollViewer>
</DockPanel>
</UserControl>
If you're wondering what the SpecialGroupBox does, it holds other controls, positioning them a certain way. There are a few of them in this window, and they work. It is inside of one of these SpecialGroupBoxes that my SpecialControl is supposed to appear.

Does your UserControl have a corresponding .xaml.cs file? This problem seems to happen when it doesn't.
If you're using Visual Studio, try copying all the XAML from your UserControl, then deleting it from your project, adding a new UserControl (with the same name as before), then pasting your content back into the XAML file. This will ensure that you have the correct .xaml.cs file set up.
See this answer.

In your post you didn't mention how you are using the listViewTemplate . if your using inside listview/listbox you can try like this it will load the user control:
<ListView ItemsSource="{Binding Items}">
<ListView.ItemTemplate>
<DataTemplate >
<ContentControl ContentTemplate="{StaticResource listviewDataTemplate}" Content="{Binding}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

Adding custom class with XAML in ListBox C# WPF

I have a class PC that contains Image, Label (with XAML design) and I want to get a list of PCs in ListBox in other class.
I tried this, but I get error System.Windows.Markup.XamlParseException:
pc p = new pc();
list_pc.Items.Add(p);
(where list_pc is a ListBox)
This is the XAML for a single PC:
<Window
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" mc:Ignorable="d"
x:Class="TnCyberCafe.pc"
Title="pc"
SizeToContent="WidthAndHeight"
ShowInTaskbar="False"
WindowStartupLocation="CenterScreen"
WindowStyle="None"
AllowsTransparency="True"
Background="Transparent" Width="95" Height="104.982">
<Grid HorizontalAlignment="Left" Margin="0,10,-15,10" Width="110">
<Image x:Name="image" HorizontalAlignment="Left" Height="96" VerticalAlignment="Top" Width="100" Source="Resources/aaa.png" RenderTransformOrigin="0.5,0.26" Margin="0,-16,0,0"/>
<Label Content="Label" HorizontalAlignment="Left" Height="25" Margin="20,70,0,-10" VerticalAlignment="Top" Width="45"/>
</Grid>
</Window>
This is the XAML for my list_pc:
<ListBox x:Name="liste_pc" ScrollViewer.VerticalScrollBarVisibility="Disabled">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel IsItemsHost="True" Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
List PCs
</ListBox>

Your first question regarding the System.Windows.Markup.XamlParseException:
As Garry Vass mentioned something went wrong, but does not tell you exactly what happened. If you are developing in Visual Studio, Click on Exceptions under Debug Tab and enable Common Language Runtime Exceptions. This will point you to the Error Code.
For the second question you should have databindings and ListBox Itemtemplate as below
<ListBox x:Name="liste_pc" ItemsSource="{Binding PCList}" ScrollViewer.VerticalScrollBarVisibility="Disabled">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Image Source="{Binding PCImageSource}" />
<Label Content="{Binding Path=PCName}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
where PCList is the observable collection of PC Class object items