C# ListView中所选行的双倍高度

阿罗哈

我的XAML代码中有一个ListView，里面有一个网格

现在有一段来自我同事的代码，我需要完成。 目标是将选定行的高度增加一倍。下面的截图是第一行高度的两倍，但不是选定的

<Grid.Style>
 <Style TargetType="Grid">
  <Setter Property="HeightRequest" Value="60"/>
   <Style.Triggers>
    <DataTrigger TargetType="Grid" Binding="{Binding Selected}" Value="True">
     <Setter Property="HeightRequest" Value="120"/>
    </DataTrigger>
   </Style.Triggers>
 </Style>
</Grid.Style>

我必须改变什么，选定的对象就是那个具有双倍高度的对象？我正在与xamarin/xamarin forms UWP/Android合作

---

附加信息：我必须在MVVM模式下工作。所以我应该避免使用传统事件

如果要在运行时更改ViewCell的高度。您可以调用

cell.ForceUpdateSize（）

以更新单元格的大小

因此，我们使用

TriggerAction

来更改此值，并告诉ViewCell更新其大小

public class ForceUpdateSizeTriggerAction : TriggerAction<VisualElement>
{
    public int HeighRequest { set; get; }

    public ForceUpdateSizeTriggerAction() : base()
    {

    }
    protected override void Invoke(VisualElement sender)
    {
        var parent = sender.Parent;
        while (parent != null && !(parent is ViewCell))
        {
            parent = parent.Parent;
        }
        if (parent is ViewCell cell)
        {
            Device.BeginInvokeOnMainThread(() =>
            {
                sender.HeightRequest = HeighRequest;
                cell.ForceUpdateSize();
            });
        }
    }
}

<ListView  HasUnevenRows="True" ItemsSource="{Binding MyItems}" SelectedItem="{Binding SelectItems,Mode=TwoWay}">

<Grid.Style>
   <Style TargetType="Grid">
      <Setter Property="HeightRequest" Value="60"/>
      <Style.Triggers>
        <DataTrigger TargetType="Grid" Binding="{Binding IsCheck}" Value="True">
            <DataTrigger.EnterActions>
                <local:ForceUpdateSizeTriggerAction HeighRequest="120" />
            </DataTrigger.EnterActions>

            <DataTrigger.ExitActions>
                <local:ForceUpdateSizeTriggerAction HeighRequest="60" />
            </DataTrigger.ExitActions>
        </DataTrigger>
      </Style.Triggers>
   </Style>
</Grid.Style>

public class MyViewModel : INotifyPropertyChanged
{

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public ObservableCollection<Model> MyItems { get; set; }

    private Model selectItems;
    public Model SelectItems
    {
        get
        {
            return selectItems;
        }

        set
        {
            if (selectItems != value)
            {

                selectItems = value;
                NotifyPropertyChanged();
                foreach(Model model in MyItems)
                {
                    if(selectItems==model)
                    {
                        model.IsCheck = !model.IsCheck;                         
                    }
                }
            }
        }
    }

    public MyViewModel()
    {
        SelectItems = null;

        MyItems = new ObservableCollection<Model>() {

            new Model(){ IsCheck=false},
            new Model(){ IsCheck=false},
            new Model(){ IsCheck=false},
            new Model(){ IsCheck=false},
            new Model(){ IsCheck=false},
            new Model(){ IsCheck=false},
            new Model(){ IsCheck=false},



        };

 }

public class Model : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }



    private bool isCheck;
    public bool IsCheck
    {
        get
        {
            return isCheck;
        }

        set
        {
            if (isCheck != value)
            {
                isCheck = value;
                NotifyPropertyChanged();
            }
        }
    }

    private double height;
    public double Height
    {
        get
        {
            return height;
        }

        set
        {
            if (height != value)
            {
                height = value;
                NotifyPropertyChanged();
            }
        }
    }

}