Question

如何更改listview selected / ItemTapped项文本颜色Xamarin.forms。

以下是我的代码

namespace StoreProject.View
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class SelectFilters : ContentPage
    {
        public ObservableCollection<Item> Items { get; set; } = new ObservableCollection<Item>();


        public SelectFilters()
        {
            InitializeComponent();
            BindingContext = this;

            Items.Add(new Item { Name = "GENDER" });
            Items.Add(new Item { Name = "SIZE" });
            Items.Add(new Item { Name = "STYLE" });
            Items.Add(new Item { Name = "BRAND" });
            Items.Add(new Item { Name = "PRICE" });
            Items.Add(new Item { Name = "COLOR" });

        }

        private void lstView_ItemSelected(object sender, ItemTappedEventArgs e)
        {
            try
            {
                //   string itm = e.SelectedItem.ToString();
                var dataItem = e.Item as Item;

                dataItem.TextColor = Color.Red;
                dataItem.OnPropertyChanged();
                // update listView
                dataItem.OnPropertyChanged();

            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex);

            }
        }
    }

    public class Item : INotifyPropertyChanged
    {
        public string Name { get; set; }

        public Color TextColor { get; set; } = Color.Black;

        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged()
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(""));
        }
    }
}

Answer 1

您必须为ListView ItemsSource的视图模型设置颜色属性。实施INotifyPropertyChanged，以便在更改列表视图的内容时更新ListView：

public class ItemViewModel : INotifyPropertyChanged
{
    ...
    public string Name { get; set; } = "";
    public Color TextColor { get; set; } = Color.Black;

    // event handler for updating the list views
    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged()
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(""));
    }
}

然后向您的ItemsSource添加一个事件监听器和ListView：

listView.ItemTapped += Tapped;

var itemsSource = new ObservableCollection<ItemViewModel>{
    new ItemViewModel { Name = "aaa" },
    new ItemViewModel { Name = "bbb" },
    new ItemViewModel { Name = "ccc" },
    new ItemViewModel { Name = "ddd" },
    new ItemViewModel { Name = "eee" },
    new ItemViewModel { Name = "fff" },
};
listView.ItemsSource = itemsSource;

并设置所选项目的文字颜色：

void Tapped(object sender, ItemTappedEventArgs args)
{
    var listView = sender as ListView;
    var selectedItem = args.Item as ItemViewModel;

    // set the text color of the selected item
    foreach (ItemViewModel item in listView.ItemsSource) {

        // set the text color
        // reset text color if the items are not selected
        item.TextColor = selectedItem.Equals(item) ? Color.Green : Color.Black;

        // update listView
        item.OnPropertyChanged();

    }
}

XAML中的ListView Binding字段为TextColor：

<ListView x:Name="listView">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <AbsoluteLayout>
                    <Label Text="{Binding Name}"
                        TextColor="{Binding TextColor}"
                        AbsoluteLayout.LayoutFlags="All"
                        AbsoluteLayout.LayoutBounds="0.5, 0.5, 0.9, 0.9"/>
                </AbsoluteLayout>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

如何更改listview所选项目文本颜色Xamarin.forms

1 个答案: