拉伸GridViewItem以填充屏幕

Question

我正在创建一个类似于windows8日历app的应用程序，但我遇到了一个问题。

那么如何在GridView中拉伸我的组以填充所有可用空间（与windows应用程序中的月视图相同）？我试图设置HorizontalContentAlignment的属性GridViewItem，但它没有生效。

  <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <GridView Padding="116,37,40,46" ItemsSource="{Binding Source={StaticResource DayGroups}}">
      <GridView.ItemTemplate>
        <DataTemplate>
          <Grid>
            <TextBlock Text="{Binding Day}" />
          </Grid>  
        </DataTemplate>
      </GridView.ItemTemplate>
      <GridView.ItemContainerStyle>
        <Style TargetType="GridViewItem">
          <Setter Property="HorizontalContentAlignment" Value="Stretch" />
        </Style>
      </GridView.ItemContainerStyle>
      <GridView.ItemsPanel>
        <ItemsPanelTemplate>
          <VirtualizingStackPanel Orientation="Horizontal" />
        </ItemsPanelTemplate>
      </GridView.ItemsPanel>
      <GridView.GroupStyle>
        <GroupStyle>
          <GroupStyle.HeaderTemplate>
            <DataTemplate>
              <Grid>
                <TextBlock Text="{Binding Key}" Style="{StaticResource SubtitleTextBlockStyle}"
                           HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
              </Grid>
            </DataTemplate>
          </GroupStyle.HeaderTemplate>
          <GroupStyle.Panel>
            <ItemsPanelTemplate>
              <VariableSizedWrapGrid />
            </ItemsPanelTemplate>
          </GroupStyle.Panel>
        </GroupStyle>
      </GridView.GroupStyle>
    </GridView>
  </Grid>

由于

---

ItemSource只是

的集合

  public class GroupViewModel<TKey, TItem> : ViewModelBase
  {
    private ObservableCollection<TItem> _items;
    private TKey _key;

    public TKey Key
    {
      get { return _key; }
      set { Set(ref _key, value); }
    }

    public ObservableCollection<TItem> Items
    {
      get { return _items; }
      set { Set(ref _items, value); }
    }
  }

其中TKey为string，TItem为DateTime