WPF

<ListBox Name="myListBox">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<VirtualizingStackPanel Orientation = "Vertical"/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
</ListBox>

<StackPanel Orientation="Horizontal">
<TextBox Text="Hello"/>
<ComboBox Name="cmbItems"/>
</StackPanel>

<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Path=Item}"/>
<TextBlock Text="{Binding Path=AnotherItem}"/>
</DataTemplate>
</ListBox.ItemTemplate>

Tarun.K.S wrote:

Actually VirtualizingStackPanel is mainly used to set the
ItemsPanelTemplate for lets take an example for a

ListBox <br />

where large data like 10,000 items or more have to be loaded into it.

SledgeHammer01 wrote:

Even with 200 items you will see a huge difference.

SledgeHammer01 wrote:

Ask me how I know

SledgeHammer01 wrote:

I saw 200 items add about 50MB of memory when I turned virtualization off. Thats how I know

SledgeHammer01 wrote:

10 - 20 items realized vs. 200 items realized is a HUGE memory difference. Unless 50MB isn't considered "huge"

devvvy wrote:

VirtualizingStackPanel carries more overhead than a simple Grid/StackPanel.

private ObservableCollection<Directive> list;

void DerivedAttributePanel_Loaded(object sender,RoutedEventArgs e)
        {              
            list = new ObservableCollection<Directive>();
            list.Add(new Directive { DirectiveName = "Filter1", Description = "Description 1" });
            list.Add(new Directive { DirectiveName = "Filter2", Description = "Description 2" });
            list.Add(new Directive { DirectiveName = "Filter3", Description = "Description 3" });
           
            lbDirectiveList.ItemsSource = list;
         }

//Suppose you have a Button to add data
// No need of setting the ItemsSource again!
private void AddData_Click(object sender, RoutedEventArgs e)
{
 Directive newDirect = new Directive { DiretiveName = txtFilter.Text, Description = txtDesc.Text };
 list.Add(newDirect);
}

<ListBox ItemsSource="{Binding lbDirectiveList}" ItemTemplate="{StaticResource myDataTemplate}" />

<ListBox Name=" "...>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Path=DirectiveName}"/>
<TextBlock Text="{Binding Path=Description}"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>