如何在 sfListView 中对复选框进行分组和绑定？

Answer 1

SfListView 允许像复选框选择一样选择每个组和组中的项目。每当使用转换器选择和取消选择项目时，都会更新 GroupHeader 模板中的复选框状态。

在 XAML 中：

<ContentPage xmlns:syncfusion="clr-namespace:Syncfusion.ListView.XForms;assembly=Syncfusion.SfListView.XForms">
    <syncfusion:SfListView>
        <syncfusion:SfListView.GroupHeaderTemplate>
            <DataTemplate>
                <ViewCell>
                    <ViewCell.View>
                        <Grid BackgroundColor="#d3d3d3">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="30" />
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition Width="Auto" />
                            </Grid.ColumnDefinitions>
                            <Label Text="{Binding Key}" Grid.Column="1" VerticalTextAlignment="Center"/>
                            <Image Grid.Column="2" IsVisible="{Binding SelectionMode, Source={x:Reference listView}}" HorizontalOptions="Center" VerticalOptions="Center" Source="{Binding ., Converter={StaticResource GroupingSelectionConverter}, ConverterParameter={x:Reference listView}}">
                                <Image.GestureRecognizers>
                                    <TapGestureRecognizer Tapped="TapGestureRecognizer_Tapped"/>
                                </Image.GestureRecognizers>
                            </Image>
                        </Grid>
                    </ViewCell.View>
                </ViewCell>
            </DataTemplate>
        </syncfusion:SfListView.GroupHeaderTemplate>
    </syncfusion:SfListView>
</ContentPage>

在转换器中：

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
 if (value == null)
return value;

GroupResult groupResult = value as GroupResult;
SfListView list = parameter as SfListView;

var items = new List<MusicInfo>(groupResult.Items.ToList<MusicInfo>());

 if ((items.All(item => item.IsSelected == false)))
 {
for (int i = 0; i < items.Count(); i++)
{
    var item = items[i];
    (item as MusicInfo).IsSelected = false;
    list.SelectedItems.Remove(item);
}
return ImageSource.FromResource("CustomSelection.Images.NotSelected.png");
}

else if ((items.All(item => item.IsSelected == true)))
{
for (int i = 0; i < items.Count(); i++)
{
    var item = items[i];
    (item as MusicInfo).IsSelected = true;
    list.SelectedItems.Add(item);
}
return ImageSource.FromResource("CustomSelection.Images.Selected.png");
}

else
return ImageSource.FromResource("CustomSelection.Images.Intermediate.png");
}

在 xaml.cs 页面中，

using Syncfusion.ListView.XForms.Control.Helpers;
private void TapGestureRecognizer_Tapped(object sender, EventArgs e)
{
var image = (sender as Image);
var groupResult = image.BindingContext as GroupResult;

if (groupResult == null)
    return;
var items = groupResult.Items.ToList<MusicInfo>().ToList();

if ((items.All(listItem => listItem.IsSelected == true)))
{
   for (int i = 0; i < items.Count(); i++)
    {
        var item = items[i];
        (item as MusicInfo).IsSelected = false;
    }
}
else if ((items.All(listItem => listItem.IsSelected == false)))
{
    for (int i = 0; i < items.Count(); i++)
    {
        var item = items[i];
        (item as MusicInfo).IsSelected = true;
    }
}
this.RefreshGroupHeader(groupResult);
listView.RefreshView();
}

private void RefreshGroupHeader(GroupResult group)
{
foreach (var item in this.listView.GetVisualContainer().Children)
{
    if (item.BindingContext == group)
    {
        item.BindingContext = null;
        (item as GroupHeaderItem).Content.BindingContext = null;
    }
}
}