c# – Xamarin：用于Android和Windows UWP的Xamarin表单中的分组列表的垂直字母索引(跳转列表)

我已经为ios,android和windows平台设计了Xamarin表单的分组列表视图.当我在列表视图中设置GroupShortNameBindingproperty时,垂直索引(跳转列表)会自动出现在IOS中.但跳转列表不会出现在android中.如何使用自定义渲染在android和windows中获得垂直索引的支持.如果任何人都可以提供跨平台支持此功能的自定义渲染源.

解决方法

如果你不想要Customrenders,最简单的方法是使用XAML hack.

您可以将ListView包装在RelativeLayout中,其高度和宽度等于父(内容页面).

对于列表视图,使用height作为父级,宽度为父级的90％.
添加宽度为10％的堆栈布局,从相对布局的90％开始,高度为父级.使其方向垂直.将所有字母表添加到堆栈布局作为标签,并在其特定位置实现其TapGesture到ScrollTo.

Android的宽度为90％仅适用于iOS,Windows保持为100％,堆栈布局宽度为0％,IsVisible = false.

viewmodel：

public class JumpListviewmodel : INotifyPropertyChanged
{
    private ObservableCollection<Item> _allItems;
    private List<string> _alphabetList;

    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChangedInvocator]
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null) => PropertyChanged?.Invoke(this,new PropertyChangedEventArgs(propertyName));

    public JumpListviewmodel()
    {
        AllItems = new ObservableCollection<Item>(new List<Item> { new Item { MyText = "1" },new Item { MyText = "2" },new Item { MyText = "3" } });

        AlphabetList = "ABCDEFGHIJKLMnopQRSTUVWXYZ".tochararray().Select(x => x.ToString()).ToList();
    }

    public ObservableCollection<Item> AllItems
    {
        get { return _allItems; }
        set
        {
            _allItems = value;
            OnPropertyChanged();
        }
    }

    public List<string> AlphabetList
    {
        get { return _alphabetList; }
        set
        {
            _alphabetList = value;
            OnPropertyChanged();
        }
    }
}

查看：

<RelativeLayout VerticalOptions="FillAndExpand">

    <ListView VerticalOptions="FillAndExpand" HasUnevenRows="True" ItemsSource="{Binding AllItems}"
              SeparatorColor="Transparent" SeparatorVisibility="None" BackgroundColor="Transparent"
              RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativetoParent,Property=Height,Factor=1}">
      <RelativeLayout.WidthConstraint>
        <OnPlatform x:TypeArguments="Constraint" Android="{ConstraintExpression Type=RelativetoParent,Property=Width,Factor=0.9}"
                    iOS="{ConstraintExpression Type=RelativetoParent,Factor=1}"
          WinPhone="{ConstraintExpression Type=RelativetoParent,Factor=1}" />
      </RelativeLayout.WidthConstraint>

      <ListView.ItemTemplate>
        <DataTemplate>
          <ViewCell>

            <StackLayout HorizontalOptions="FillAndExpand" BackgroundColor="Silver">

              <Label Text="{Binding MyText}" />
              <Button Text="button" />
              <BoxView HeightRequest="1" Color="Gray" BackgroundColor="Gray" HorizontalOptions="FillAndExpand" />

            </StackLayout>

          </ViewCell>
        </DataTemplate>
      </ListView.ItemTemplate>
    </ListView>

    <ListView VerticalOptions="FillAndExpand" HasUnevenRows="True" ItemsSource="{Binding AlphabetList}"
              SeparatorColor="Transparent" SeparatorVisibility="None" BackgroundColor="Transparent"
              RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativetoParent,Factor=0.9}"
      RelativeLayout.YConstraint="{ConstraintExpression Type=RelativetoParent,Factor=0.05}"
      RelativeLayout.XConstraint="{ConstraintExpression Type=RelativetoParent,Factor=0.9}">
      <RelativeLayout.WidthConstraint>
        <OnPlatform x:TypeArguments="Constraint" Android="{ConstraintExpression Type=RelativetoParent,Factor=0.1}"
                    iOS="{ConstraintExpression Type=RelativetoParent,Factor=0,Constant=0}"
          WinPhone="{ConstraintExpression Type=RelativetoParent,Constant=0}" />
      </RelativeLayout.WidthConstraint>
      <ListView.IsVisible>
        <OnPlatform x:TypeArguments="x:Boolean" WinPhone="False" iOS="False" Android="True" />
      </ListView.IsVisible>
      <ListView.ItemTemplate>
        <DataTemplate>
          <ViewCell>
            <Label Text="{Binding .}" TextColor="Red" FontSize="Micro" />
          </ViewCell>
        </DataTemplate>
      </ListView.ItemTemplate>
    </ListView>

  </RelativeLayout>

Android屏幕截图：