Hi

Here is a problem that one of my colleagues who is just starting to use WPF got himself into. He was working on an application that displays items using an ItemsControl and uses a DataTemplate. Inside the DataTemplate he used an Image. Here is the Xaml code:

   1: <Window.Resources>

   2:         <Image Source="Creek.jpg" x:Key="IMG"></Image>

   3:     </Window.Resources>

   4:     <Grid>

   5:         <ItemsControl ItemsSource="{Binding}">

   6:             <ItemsControl.ItemTemplate>

   7:                 <DataTemplate>

   8:                     <Border BorderThickness="2" BorderBrush="Black" 

   9:                             CornerRadius="3" MinHeight="10">

  10:                         <ContentControl Content="{StaticResource IMG}"/>

  11:                     </Border>

  12:                 </DataTemplate>

  13:             </ItemsControl.ItemTemplate>

  14:         </ItemsControl>

  15:     </Grid>

This is a much simpler example, but the principal is the same.

Can you see what was he doing wrong?

Hi

In my latest article I discussed Scrolling and Binding to large collections in WPF. We saw some disturbing behavior when binding a large collection to an ItemsControl. After Further Examination I found out very interesting things regarding that matter.

Memory Consumption

We saw that the application used about 500MB of Ram. Lets look at the code again:

We have all used WPF DataTemplates, but I bet most of you never gave thought to the meaning of the x:Key attribute. We all know the meaning of the DataType attribute, which determines to what type of data the template will apply to. But what about the x:Key why is it there? Lets tale a look at the following code:

<Window.Resources>
        <DataTemplate DataType="{x:Type data:s}">
            <Button Width="50" Height="50">
                <TextBlock Text="{Binding text}"></TextBlock>
            </Button>
        </DataTemplate>
    </Window.Resources>
    <Canvas>
        <ItemsControl ItemsSource="{Binding}">
        </ItemsControl>
    </Canvas>

Often we want to display a list of elements and allow the user to sort them in various ways. There are many ways to do it and I wanted to show you how to use a SortDescription Object. What is a SortDescription object you ask? It receives two parameters in its constructor: the first is [...]