Virtualize the loading of Windows 8 XAML controls within a grid - windows-runtime

Question

I have a Window 8 RT store application (XAML/C#).
I have a form with a grid as the main component. That grid has 50 rows and each row has a TextBox. The grid is wrapped in a scrollviewer:
<ScrollViewer>
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
...50 rows
</Grid.RowDefinitions>
<TextBox Grid.Row="0" />
<TextBox Grid.Row="1" />
<TextBox Grid.Row="2" />
...
<TextBox Grid.Row="50" />
</Grid>
</ScrollViewer>
When this form is loaded there is a notable pause while the page is loaded, I guessing this is because the page is being drawn.
What is the best way to speed this load process up? Can I virtualize the loading of the grid/Textboxes?
The slowness is notable once the application is running on a Windows Surface tablet, it's not bad on my design PC but that is obviously much more powerful.
Thanks in advance.

Answer 1

You can use a ListView instead of the Grid in a ScrollViewer since that supports virtualization by default. Other than that - it might be nice to have some nicer user experience than a scary long list of TextBoxes to fill - maybe break up your form in multiple pages or use a FlipView to flip between groups of fields.
*EDIT - example
XAML
<Page
x:Class="App10.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App10"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Page.Resources>
<DataTemplate
x:Key="TextFieldTemplate">
<Grid>
<Grid.RowDefinitions>
<RowDefinition
Height="Auto" />
<RowDefinition
Height="Auto" />
</Grid.RowDefinitions>
<TextBlock
Text="{Binding Label}" />
<TextBox
Text="{Binding Value, Mode=TwoWay}"
Grid.Row="1" />
</Grid>
</DataTemplate>
<DataTemplate
x:Key="BoolFieldTemplate">
<CheckBox
Content="{Binding Label}"
IsChecked="{Binding Value, Mode=TwoWay}" />
</DataTemplate>
<local:FieldTemplateSelector
x:Key="FieldTemplateSelector"
TextTemplate="{StaticResource TextFieldTemplate}"
BoolTemplate="{StaticResource BoolFieldTemplate}" />
</Page.Resources>
<Grid
Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
<ListView
x:Name="lv"
ItemTemplateSelector="{StaticResource FieldTemplateSelector}" />
</Grid>
</Page>
C#
using System.Collections.Generic;
using App10.Common;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
namespace App10
{
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
this.lv.ItemsSource =
new List<object>(
new object[]
{
new BoolFieldViewModel { Label = "Some bool field" },
new TextFieldViewModel { Label = "Some text field" },
new TextFieldViewModel { Label = "Some text field" },
new BoolFieldViewModel { Label = "Some bool field" },
new BoolFieldViewModel { Label = "Some bool field" },
new TextFieldViewModel { Label = "Some text field" },
});
}
/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached. The Parameter
/// property is typically used to configure the page.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
}
}
public abstract class FieldViewModel<T> : BindableBase
{
public string Label { get; set; }
#region Value
private T _value;
public T Value
{
get { return _value; }
set { this.SetProperty(ref _value, value); }
}
#endregion
}
public class BoolFieldViewModel : FieldViewModel<bool> { }
public class TextFieldViewModel : FieldViewModel<string> { }
public class FieldTemplateSelector : DataTemplateSelector
{
public DataTemplate BoolTemplate { get; set; }
public DataTemplate TextTemplate { get; set; }
protected override DataTemplate SelectTemplateCore(object item, DependencyObject container)
{
if (item is BoolFieldViewModel) return BoolTemplate;
if (item is TextFieldViewModel) return TextTemplate;
return base.SelectTemplateCore(item, container);
}
}
}