滚动CollectionView到ItemGroup

Question

我有一个小组的CollectionView。每个组都有一个带有日期的字符串。

随后，我创建了一个CarouselView，其中包含了CollectionView组的所有日期。

我正在尝试创建一种方法来滚动CarouselView的元素，从而将CollectionView滚动到相应的组，但是它不起作用。

CollectionView仍然是静止的。

<CollectionView x:Name="CollectionDiary"....../>

c#

public class HumorGroup : ObservableCollection<HumorDiary>
{
     public string Name { get; private set; }

     public HumorGroup(string name, ObservableCollection<HumorDiary> icon) : base(icon)
     {
         Name = name;
     }
}

public ObservableCollection<HumorGroup> TotHumor { get; private set; } = new ObservableCollection<HumorGroup>();

HumorGroup group = new HumorGroup("Month" + " " + Year, new ObservableCollection<HumorDiary>());  

TotHumor.Add(group);
group.Add(item HumorDiary);

 private void ScrollCollectionView_Clicked(object sender, EventArgs e)
 {
     var current = CarouselView.CurrentItem as HumorGroup;
     CollectionDiary.ScrollTo(current, position: ScrollToPosition.Start);
 }

Answer 1

--我正在尝试创建一种方法来滚动CarouselView的元素，从而将CollectionView滚动到相应的组，但是它不起作用。

我同意Jason的观点，您可以让CollectionView滚动到CarouselView_Scrolled事件中当前组的第一项。

 private void CarouselView_Scrolled(object sender, ItemsViewScrolledEventArgs e)
    {
        var current = CarouselView1.CurrentItem as HumorGroup;
        if(current!=null)
        {             
            CollectionDiary.ScrollTo(current.FirstOrDefault(),ScrollToPosition.Center);
        }
        
    }

我做了一个样本，你可以看看：

<StackLayout>
        <CarouselView
            x:Name="CarouselView1"
            ItemsSource="{Binding humors}"
            Scrolled="CarouselView_Scrolled">
            <CarouselView.ItemTemplate>
                <DataTemplate>
                    <StackLayout>
                        <Label Text="{Binding Name}" />
                    </StackLayout>
                </DataTemplate>
            </CarouselView.ItemTemplate>

        </CarouselView>
        <CollectionView
            x:Name="CollectionDiary"
            HeightRequest="100"
            IsGrouped="True"
            ItemsSource="{Binding humors}"
            SelectionMode="Single">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <StackLayout Orientation="Horizontal">
                        <Label Text="{Binding name}" />
                        <Label Text="{Binding count}" />
                    </StackLayout>
                </DataTemplate>
            </CollectionView.ItemTemplate>
            <CollectionView.GroupHeaderTemplate>
                <DataTemplate>
                    <Label
                        BackgroundColor="LightGray"
                        FontAttributes="Bold"
                        FontSize="Large"
                        Text="{Binding Name}" />
                </DataTemplate>
            </CollectionView.GroupHeaderTemplate>
        </CollectionView>
    </StackLayout>

 public partial class Page8 : ContentPage
{
    public GroupHumorViewmodel groups { get; set; }
    public Page8()
    {
        InitializeComponent();
        groups = new GroupHumorViewmodel();
        this.BindingContext =groups;
    }

    private void CarouselView_Scrolled(object sender, ItemsViewScrolledEventArgs e)
    {
        var current = CarouselView1.CurrentItem as HumorGroup;
        if(current!=null)
        {             
            CollectionDiary.ScrollTo(current.FirstOrDefault(),ScrollToPosition.Center);
        }
        
    }
}

public class HumorDiary
{
    public string name { get; set; }
    public int count { get; set; }
}

public class HumorGroup:ObservableCollection<HumorDiary>
{
    public string Name { get;  set; }
    public HumorGroup(string name, ObservableCollection<HumorDiary> humor) : base(humor)
    {
        Name = name;
    }
}

public class GroupHumorViewmodel
{
    public ObservableCollection<HumorGroup> humors { get; set; }

    public GroupHumorViewmodel()
    {          
        humors = new ObservableCollection<HumorGroup>();
        humors.Add(new HumorGroup("2021",new ObservableCollection<HumorDiary>() {
            new HumorDiary(){name="2021-day1",count=3},
            new HumorDiary(){name="2021-day2",count=3},
            new HumorDiary(){name="2021-day3",count=4},
            new HumorDiary(){name="2021-day4",count=2},
            new HumorDiary(){name="2021-day5",count=5},
            new HumorDiary(){name="2021-day6",count=4},
            new HumorDiary(){name="2021-day7",count=2},
            new HumorDiary(){name="2021-day8",count=5}


        }));

        humors.Add(new HumorGroup("2020", new ObservableCollection<HumorDiary>() {
            new HumorDiary(){name="2020-day1",count=3},
            new HumorDiary(){name="2020-day2",count=3},
            new HumorDiary(){name="2020-day3",count=4},
            new HumorDiary(){name="2020-day4",count=2},
            new HumorDiary(){name="2020-day5",count=5},
            new HumorDiary(){name="2020-day6",count=4},
            new HumorDiary(){name="2020-day7",count=2},
            new HumorDiary(){name="2020-day8",count=5}


        }));

        humors.Add(new HumorGroup("2019", new ObservableCollection<HumorDiary>() {
            new HumorDiary(){name="2019-day1",count=3},
            new HumorDiary(){name="2019-day2",count=3},
            new HumorDiary(){name="2019-day3",count=4},
            new HumorDiary(){name="2019-day4",count=2},
            new HumorDiary(){name="2019-day5",count=5},
            new HumorDiary(){name="2019-day6",count=4},
            new HumorDiary(){name="2019-day7",count=2},
            new HumorDiary(){name="2019-day8",count=5}


        }));
      
    }
}