更改 ListView .NET MAUI 中特定单元格的背景

Question

我的 ListView 包含名为“Item”的对象列表 我希望单击某个项目后，将其背景颜色更改为不同的颜色。 我的问题是我无法访问特定的单元格。我可以使用

list.selectedItem

访问该项目，但不能使用包含他的单元格

            this.list = new ListView
            {
                ItemsSource = new ObservableCollection<Item>(Lists.Items),
                ItemTemplate = new DataTemplate(() =>
                {
                    Label nameLabel = Lists.settings.CreateLabel();


                    Label descriptionLabel = Lists.settings.CreateLabel();
                    Button addButton = new Button
                    {
                        Text = "+",
                        FontSize = 16,
                        BackgroundColor = Color.FromHex(Settings.LightModeColors[0]),
                        TextColor = Colors.Black,

                    };
                    Button deductButton = new Button
                    {
                        Text = "-",
                        FontSize = 16,
                        BackgroundColor = Color.FromHex(Settings.DarkModeColors[0]),
                        TextColor = Colors.White,

                    };
                    Label quantityLabel=Lists.settings.CreateLabel("0");
                    nameLabel.SetBinding(Label.TextProperty, nameof(Item.Name));
                    descriptionLabel.SetBinding(Label.TextProperty, nameof(Item.Description));
                    addButton.Clicked += async (sender, args) =>
                    {
                        quantityLabel.Text = "" + (int.Parse(quantityLabel.Text) + 1);
                        Debug.WriteLine(args.GetType());
                        AddItem("id");
                    };
                    deductButton.Clicked += async (sender, args) =>
                    {
                        if (quantityLabel.Text != "0")
                        { 
                            
                            quantityLabel.Text = "" + (int.Parse(quantityLabel.Text) - 1);
                            DeductItem(nameof(Item.Id));
                        }
                    };

                    Grid templateLayout = new Grid
                    {
                        RowDefinitions =
                        {
                            new RowDefinition{Height=new GridLength(1,GridUnitType.Star) },
                        },
                        ColumnDefinitions =
                        {
                            new ColumnDefinition{Width=new GridLength(3,GridUnitType.Star) },
                            new ColumnDefinition{Width=new GridLength(2,GridUnitType.Star) },
                            new ColumnDefinition{Width=new GridLength(1,GridUnitType.Star) },
                            new ColumnDefinition{Width=new GridLength(1,GridUnitType.Star) },
                            new ColumnDefinition{Width=new GridLength(1,GridUnitType.Star) },

                        },
                    };
                    templateLayout.Add(nameLabel, 0, 0);
                    templateLayout.Add(descriptionLabel, 1, 0);
                    templateLayout.Add(addButton, 2, 0);
                    templateLayout.Add(quantityLabel, 3, 0);
                    templateLayout.Add(deductButton, 4, 0);
                    
                    return new ViewCell { View = templateLayout };
                })

            };

            list.ItemTapped += OnItemTapped;
        private void OnItemTapped(object sender, ItemTappedEventArgs e) 
        {
            //list.SelectedItem = null;
            Debug.WriteLine(sender.GetType());
            Debug.WriteLine(((ListView)sender).SelectedItem.GetType());
            Debug.WriteLine(e.GetType());
            Debug.WriteLine(e.ItemIndex.GetType());
            Debug.WriteLine(e.Item.GetType());

        }

尝试调试以在listview中找到某种类型的View对象

Answer 1

您可以尝试使用 Visual State 来更改 SelectedItem 的背景颜色，我认为这是最简单的方法。但在这里我建议使用 CollectionView 而不是

ListView

，因为

CollectionView

旨在为 ListView 提供更灵活、更高效的替代方案。 （由于某种原因，视觉状态在 ListView 中不起作用）

这是在代码后面添加视觉状态的示例。

this.list = new CollectionView()
{
    ItemsSource = items,
    SelectionMode = SelectionMode.Single,
    ItemTemplate = new DataTemplate(() =>
    {
        Label nameLabel = new Label();
        Label descriptionLabel = new Label();
        ...
        ...
        //Define Visual States here
        var vsgs = new VisualStateGroupList();
        var vsg = new VisualStateGroup() { Name = "CommonStates" };
        var vs_normal = new VisualState { Name = "Normal" };
        var vs_selected = new VisualState { Name = "Selected" };
        vs_normal.Setters.Add(new Setter { Property = BackgroundColorProperty, Value = Colors.White });
        vs_selected.Setters.Add(new Setter { Property = BackgroundColorProperty, Value = Colors.Green });
        vsg.States.Add(vs_normal);
        vsg.States.Add(vs_selected);
        vsgs.Add(vsg);

        Grid templateLayout = new Grid
        {
            ...
        };
        templateLayout.Add(nameLabel, 0, 0);
        ...
        templateLayout.Add(deductButton, 4, 0);

        //Set VisualStates on the Grid
        VisualStateManager.SetVisualStateGroups(templateLayout, vsgs);


        return templateLayout;
    })
};

希望有帮助！