Souvik Basu Souvik Basu - 2 months ago 6
C# Question

How to display items in Canvas through Binding

I have list of items that I want to display in Canvas using data binding.

ItemsToShowInCanvas = new ObservableCollection<ItemDetail>
{
new ItemDetail {Text = "ABC", Top = 10, Left = 200},
new ItemDetail {Text = "DEF", Top = 100, Left = 300},
new ItemDetail {Text = "PQR", Top = 50, Left = 150}
};


ItemDetail is a simple class with auto properties for Text, Top and Left values

public class ItemDetail
{
public string Text { get; set; }
public double Top { get; set; }
public double Left { get; set; }
}


When I databind the items, they do appear in canvas. But the items do not appear at positions mentioned using Top and Left properties.

<Canvas>
<ItemsControl ItemsSource="{Binding Path=ItemsToShowInCanvas}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Text}" Canvas.Top="{Binding Path=Top}" Canvas.Left="{Binding Path=Left}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Canvas>

Answer

Set the ItemsPanel to a Canvas and bind the containers instead of the TextBlock in the DataTemplate

<ItemsControl ItemsSource="{Binding Path=ItemsToShowInCanvas}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <Canvas/>
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemContainerStyle>
        <Style TargetType="ContentPresenter">
            <Setter Property="Canvas.Left" Value="{Binding Left}"/>
            <Setter Property="Canvas.Top" Value="{Binding Top}"/>
        </Style>
    </ItemsControl.ItemContainerStyle>
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Path=Text}" />
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>