Setting Canvas properties in an ItemsControl DataTemplate - c#

I'm trying to databind to this ItemsControl:
<ItemsControl ItemsSource="{Binding Path=Nodes, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
By using this DataTemplate, I'm trying to individually position my Node elements on the Canvas correctly:
<DataTemplate DataType="{x:Type Model:EndNode}">
<Controls:EndNodeControl Canvas.Left="{Binding Path=XPos}" Canvas.Top="{Binding Path=YPos}" />
</DataTemplate>
However, it's not working as expected. All my node elements are drawn on top of each other in the same position. Any suggestions on how to accomplish this?

The attached properties only work on direct children of the Canvas. ItemsControl will place ContentPresenter controls as its direct children, so you might want to add a style for that as well:
<ItemsControl ItemsSource="{Binding Path=Nodes}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style TargetType="ContentPresenter">
<Setter Property="Canvas.Left" Value="{Binding Path=XPos}" />
<Setter Property="Canvas.Top" Value="{Binding Path=YPos}" />
</Style>
</ItemsControl.ItemContainerStyle>
</ItemsControl>

Related

UniformGrid Grid.Row Grid.Column not being adhered to

Following on from this question (DataTemplateSelector for Uniform Grid binding?), I still am not getting my Buttons/Textblocks to adhere to the row and the column that they are bound to in the view model. I will only post the XAML as I know the row and column bindings are correct (Live Visual Tree tells me Row is 1 and Column is 1 for example, but on the grid it shows otherwise...).
If you need anymore code let me know. This is the small bit of XAML.
<Grid DockPanel.Dock="Left" Background="Transparent" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" MinWidth="800" Height="400">
<ItemsControl ItemsSource="{Binding ObjCompositeCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid DockPanel.Dock="Top" HorizontalAlignment="Stretch"
VerticalAlignment="Stretch" Name="objGrid" Grid.Row="1"
Rows="{Binding RowCount}"
Columns="{Binding ColumnCount}"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Grid.Row" Value="{Binding Row}"/>
<Setter Property="Grid.Column" Value="{Binding Column}"/>
</Style>
</ItemsControl.ItemContainerStyle>
<ItemsControl.Resources>
<DataTemplate DataType="{x:Type engine:ObjA}">
<Button Content="{Binding Id}" />
</DataTemplate>
<DataTemplate DataType="{x:Type engine:GridLabeller}">
<TextBlock Text="{Binding HeaderName}"/>
</DataTemplate>
</ItemsControl.Resources>
</ItemsControl>
</Grid>
A UniformGrid in WPF doesn't care about the Grid.Row and Grid.Column attached properties. You need to create a Grid with RowDefinitions and ColumnsDefinitions for setting these properties to have any effect.
You may create a Grid programmatically in the view based on the values of the RowCount and ColumnCount source properties.

Xaml Listview Windows-Universal Horizontal Scroll Mode

I coded a list that has as an Itemsource an Observable Collection, which is of type Grids. So the listview is containing 4 Items (Grids). I want the Grids to be like horizontal next to each other, so I tried this in Xaml.
<StackPanel Orientation="Horizontal">
<ListView ScrollViewer.HorizontalScrollBarVisibility="Visible" ScrollViewer.HorizontalScrollMode="Enabled" ItemsSource="{Binding DropGrids, Source={StaticResource view}}" Height="100" x:Name="DropList" RenderTransformOrigin="0.5,0.5" >
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"></StackPanel>
</ItemsPanelTemplate>
</ListView.ItemsPanel>
</ListView>
<AppBarButton Icon="MapPin" Label="Go!" HorizontalAlignment="Right"></AppBarButton>
</StackPanel>
But when I try scrolling the list to the left it is instantly going back (If you want to simulate is use WGA resolution 4 Inch Emulator) and I can't see the fourth Grid on the screen. How do I fix this?
The ListView.ItemsPanel property I got from this post:
Stackoverflow Post - Horizontal Mode
Not sure on the Grid part in your ListView itemsource, but I blogged about how to create a Horizontal ListView here
http://depblog.weblogs.us/2015/03/25/show-items-scrolling-horizontally-with-listview-in-winrt/
I hope this helps...
The complete style is set as
<Style x:Name="BaseListViewStyle" TargetType="ListView">
<Setter Property="ScrollViewer.HorizontalScrollMode" Value="Enabled" />
<Setter Property="ScrollViewer.VerticalScrollMode" Value="Disabled" />
<Setter Property="VerticalAlignment" Value="Top" />
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<VirtualizingStackPanel Orientation="Horizontal"
ScrollViewer.HorizontalScrollMode="Enabled"
ScrollViewer.VerticalScrollMode="Disabled"/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>

Layer system for images on a canvas

I am trying to figure out how I can have a layer system for my app. I am adding images to an itemscontrol and they are all rendering one on top of the other.
<ItemsControl Name="canvasDataBinding"
HorizontalAlignment="Center"
Height="512"
Width="512"
VerticalAlignment="Center"
ClipToBounds="True">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas Background="Transparent"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid>
<Image Source="{Binding Name}"
Width="{Binding Width}"
Height="{Binding Height}">
</Image>
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
For testing purposes, I tried adding Panel.Zindex="{Binding Zind}" inside the image control, and decrementing Zind every time a new image was added to the collection, but the images still render on top of each other.
I also thought about having multiple collections, each collection would be its own layer. I dont know how I would implement this with my current code though.
Edit:
I added an ItemContainerStyle:
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Panel.ZIndex" Value="{Binding Zindex}" />
</Style>
</ItemsControl.ItemContainerStyle>
Again I am binding the value of ZIndex to an int that I decrement before the image is added to the collection. It is still rendering one on top of the other.
You need to set your Canvas.Top, Canvas.Left, and Panel.ZIndex in the ItemContainerStyle so the property gets applied to the <ContentPresenter> that wraps each Image.
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Canvas.Top" Value="{Binding Y}" />
<Setter Property="Canvas.Left" Value="{Binding X}" />
<Setter Property="Panel.ZIndex" Value="{Binding Zindex}" />
</Style>
</ItemsControl.ItemContainerStyle>
When your ItemsControl gets rendered, it actually renders like this
<Canvas>
<ContentPresenter>
<Image />
</ContentPresenter>
<ContentPresenter>
<Image />
</ContentPresenter>
<ContentPresenter>
<Image />
</ContentPresenter>
</Canvas>
which is why it doesn't work to set the property on the <Image> itself.

Binding ZIndex from DataTemplate

I have a View that is basically setup like this:
<Grid>
<ViewBox>
<Grid>
<ItemsControl ItemsSource="{Binding MyItems}"
ItemTemplate="{Binding Source={StaticResource MyItemsDataTemplate}}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Grid />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</Grid>
</ViewBox>
</Grid>
The DataTemplate used here can be reduced to this:
<DataTemplate x:Key="AreaItemDisplayDataTemplate">
<Canvas Grid.ZIndex={Binding Z}>
<Grid>
// an shape is displayed here...
</Grid>
</Canvas>
I would now expect the ZIndex to be bound to the Z property of the individual items. When i debug the code, i can also see, that the Z property getter is accessed when i would expect it (whenever i raise the propertychanged event for it, eg) so i assume the binding to work correctly.
However, the ZIndex is not working as expected. The binding to the value has no effect on the actual displayed Z Order. Where am i going wrong with this code?
The content of the DataTemplate gets wrapped in a ContentPresenter so the Canvas in the DataTemplate isn't a direct child of the ItemsPanel Grid. That is the reason the ZIndex property doesn't do anything.
Move the ZIndex Binding to the ItemContainerStyle and it should work.
<ItemsControl ItemsSource="{Binding MyItems}"
ItemTemplate="{Binding Source={StaticResource MyItemsDataTemplate}}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Grid />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style TargetType="ContentPresenter">
<Setter Property="Grid.ZIndex" Value="{Binding Z}"/>
</Style>
</ItemsControl.ItemContainerStyle>
</ItemsControl>

listbox items orientation to horizontal

How to make the listbox items orientation to horizontal in the default styling of a listbox.
What i mean by default is the style which we get using blend.
Use the ItemsPanel property to replace the panel with a horizontal StackPanel:
<ListBox>
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
</ListBox>
If you want to do this in a Style, just add a Setter that sets the ItemsPanel property:
<Style TargetType="ListBox">
<!-- Rest of the style -->
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>

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