GridView with 2 columns, fill width

The result I want to achieve is pretty simple, a list with 2 columns, both with equal width. In Windows Phone 7/8 this could easily be achieved using a ListBox with a WrapPanel as ItemsPanel and setting the ItemWidth to 240 (as the screen width was 480).

Now I'm Writing a Universal App, but here the problem is that the screen is not guaranted to have a width of 480 (not even for the Phone it seems) so I can't set the ItemWidth as I want it to fill the width of the screen. I have been able to achieve almost the desired effect using the following XAML:

<GridView ItemsSource="{Binding Results}" Margin="12">
    <GridView.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Image Source="{Binding SampleImage}" />
            </Grid>
        </DataTemplate>
    </GridView.ItemTemplate>

    <GridView.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapGrid MaximumRowsOrColumns="2" Orientation="Horizontal" HorizontalChildrenAlignment="Stretch" VerticalChildrenAlignment="Stretch">
            </WrapGrid>
        </ItemsPanelTemplate>
    </GridView.ItemsPanel>
</GridView>

Which gives the following result:

As seen it successfully gives 2 columns with equal width, BUT the Grid in the GridView.ItemTemlate doesn't fill the whole width of each column. I have tried setting HorizontalAlignment="Stretch" on both that Grid and on the GridView itself witout any success. Anyone has any idea of this do this?

My solution is :

<GridView ItemsSource="{Binding Results}" Margin="12"
                       SizeChanged="GridView_SizeChanged"
                       x:Name="MyGridView">
<GridView.ItemTemplate>
    <DataTemplate>
        <Grid>
            <Image Source="{Binding SampleImage}" />
        </Grid>
    </DataTemplate>
</GridView.ItemTemplate>

<GridView.ItemContainerStyle>
            <Style TargetType="GridViewItem">
                <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
                <Setter Property="HorizontalAlignment" Value="Stretch"/>
                <Setter Property="VerticalContentAlignment" Value="Stretch"/>
                <Setter Property="VerticalAlignment" Value="Stretch"/>
            </Style>
</GridView.ItemContainerStyle>
</GridView>

Code Behind :

private void GridView_SizeChanged(object sender, SizeChangedEventArgs e)
    {
        var panel = (ItemsWrapGrid)MyGridView.ItemsPanelRoot;
        panel.ItemWidth =panel.ItemHeight= e.NewSize.Width / 2;
    }

You could try this:

<GridView.ItemContainerStyle>
    <Style
        TargetType="GridViewItem">
        <Setter
            Property="HorizontalAlignment"
            Value="Stretch" />
        <Setter
            Property="VerticalAlignment"
            Value="Stretch" />
    </Style>
 </GridView.ItemContainerStyle>

The other thing you could try is to manually set ItemWidth/ItemHeight whenever you get the SizeChanged event on the GridView.

If for some reason the above doesn't work - you could also do what I do below and update the Value of both DoubleViewModel resources on SizeChanged events:

<UserControl.Resources>
    <viewModels:DoubleViewModel
        x:Key="ItemWidth"
        Value="120" />
    <viewModels:DoubleViewModel
        x:Key="ItemHeight"
        Value="120" />
</UserControl.Resources>

...

<ItemsControl.ItemTemplate>
    <DataTemplate>
        <local:YourItemTemplateControl
            Width="{Binding Value, Source={StaticResource ItemWidth}}"
            Height="{Binding Value, Source={StaticResource ItemHeight}}" />
    </DataTemplate>
</ItemsControl.ItemTemplate>

Where DoubleViewModel is:

public class DoubleViewModel : BindableBase
{
    #region Value
    /// <summary>
    /// Backing field for the Value property.
    /// </summary>
    private double value;

    /// <summary>
    /// Gets or sets a value indicating the value.
    /// </summary>
    public double Value
    {
        get { return this.value; }
        set { this.SetProperty(ref this.value, value); }
    }
    #endregion
}

The solution I used was based in Filip Skakuns suggestion, but a slight different implementation by making a reusable User Control with this behaviour. The User Control has (among others) Columns and ItemsSource properties. I change the ItemWidth of the ItemsWrapGrid instead of the Width of the ItemTemplate and do this directly in the SizeChanged event handler.

I also needed to use a ItemsWrapGrid instead of a WrapGrid for this to work. The XAML for the final user control:

<UserControl
    x:Class="MyProject.CustomControls.ColumnGridView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    x:Name="ControlRoot">

    <Grid DataContext="{Binding ElementName=ControlRoot}">
        <GridView ItemsSource="{Binding ItemsSource}" ItemTemplate="{Binding ItemTemplate}">
            <GridView.ItemsPanel>
                <ItemsPanelTemplate>
                    <ItemsWrapGrid Orientation="Horizontal" SizeChanged="ItemsWrapGrid_SizeChanged" />
                </ItemsPanelTemplate>
            </GridView.ItemsPanel>
        </GridView>
    </Grid>
</UserControl>

And for the code-behind:

using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace MyProject.CustomControls
{
    public sealed partial class ColumnGridView : UserControl
    {
        public static readonly DependencyProperty ItemTemplateProperty =
            DependencyProperty.Register("ItemTemplate", typeof(DataTemplate), typeof(ColumnGridView), new PropertyMetadata(null));

        public DataTemplate ItemTemplate
        {
            get { return (DataTemplate)GetValue(ItemTemplateProperty); }
            set { SetValue(ItemTemplateProperty, value); }
        }

        public static readonly DependencyProperty ItemsSourceProperty =
            DependencyProperty.Register("ItemsSource", typeof(object), typeof(ColumnGridView), new PropertyMetadata(null));

        public object ItemsSource
        {
            get { return (object)GetValue(ItemsSourceProperty); }
            set { SetValue(ItemsSourceProperty, value); }
        }

        public static readonly DependencyProperty ColumnsProperty =
            DependencyProperty.Register("Columns", typeof(int), typeof(ColumnGridView), new PropertyMetadata(1));

        public int Columns
        {
            get { return (int)GetValue(ColumnsProperty); }
            set
            {
                if (value <= 0) throw new ArgumentOutOfRangeException("Columns must be greater than 0");
                SetValue(ColumnsProperty, value);
            }
        }

        public ColumnGridView()
        {
            this.InitializeComponent();
        }

        private void ItemsWrapGrid_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            ItemsWrapGrid itemsWrapGrid = sender as ItemsWrapGrid;
            if (itemsWrapGrid != null)
            {
                itemsWrapGrid.ItemWidth = e.NewSize.Width / Columns;
            }
        }
    }
}

I was able to solve something very similar just binding the Item Width to the parent ActualWidth, like this:

<ListView Name="allDevicesListView" d:DataContext="{d:DesignData /SampleData/VeraServerSampleData.xaml}" ItemsSource="{Binding Devices}">
<ListView.ItemTemplate>
    <DataTemplate>
        <StackPanel Orientation="Horizontal" Width="{Binding ElementName=allDevicesListView, Path=ActualWidth}">
            <Grid Width="{Binding ElementName=allDevicesListView, Path=ActualWidth}">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="2*"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <TextBlock Text="{Binding Name}" FontSize="24" Grid.Column="0" Margin="0,0,14.333,0" />
                <local:VeraDeviceControl VeraDeviceCategory="DimmableLight" Width="auto" Grid.Column="1"/>
            </Grid>
        </StackPanel>
    </DataTemplate>
</ListView.ItemTemplate>