c# - 列表视图 xamarin.forms 中选定项的背景颜色

Question

在 Xamarin.forms 中使用 ListView 时，在选择一个项目时，该项目保持不变，具有相当难看的背景颜色。我可以禁用此功能吗？

这是我的代码：

<StackLayout>
  <ListView x:Name="FoodList" HasUnevenRows="True" CachingStrategy="RecycleElement" ItemTapped="OnItemTapped">
    <ListView.ItemTemplate>
      <DataTemplate>
        <ViewCell>
          <StackLayout Padding="0,15,0,0" >
           <StackLayout Orientation="Horizontal" BackgroundColor="White" >
            <Image Source="{Binding image_url}" Aspect="AspectFill" HeightRequest="200" WidthRequest="200"/>
            <StackLayout Orientation="Vertical">
              <Label Text="{Binding food_name}" TextColor="Black" Style="{StaticResource MainLisTtext}" />
              <Label Text="{Binding price}" TextColor="Black" Style="{StaticResource SubLisTtext}" />
              <Label Text="{Binding food_description}" TextColor="Black" Style="{StaticResource SubLisTtext}" />
            </StackLayout>
            </StackLayout>
          </StackLayout>
        </ViewCell>vc
      </DataTemplate>
    </ListView.ItemTemplate>
  </ListView>
</StackLayout>

Answer 1

这可以通过使用自定义渲染器来完成

iOS 自定义渲染器

SelectionStyle在 iOS 上编辑属性。

下面是一个将 设置为 的UITableViewCellSelectionStyle示例None。

using System;

using UIKit;

using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;

using ListViewSample.iOS;

[assembly: ExportRenderer(typeof(ViewCell), typeof(ViewCellItemSelectedCustomRenderer))]
namespace ListViewSample.iOS
{
    public class ViewCellItemSelectedCustomRenderer : ViewCellRenderer
    {
        public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)
        {
            var cell = base.GetCell(item, reusableCell, tv);

            cell.SelectionStyle = UITableViewCellSelectionStyle.None;

            return cell;
        }
    }
}

Android 自定义渲染器

1. 创建一个新的可绘制对象，ViewCellBackground.xml并将其保存到Resources>drawable文件夹：

   <?xml version="1.0" encoding="UTF-8" ?>
   <selector xmlns:android="http://schemas.android.com/apk/res/android">
       <item android:state_pressed="true" >
           <shape android:shape="rectangle">
               <!--Change the selected color by modifying this hex value-->
               <solid android:color="#FFFFFF" />
           </shape>
       </item>
       <item>
           <shape android:shape="rectangle">
               <solid android:color="#FFFFFF" />
           </shape>
       </item>
   </selector>
   

2. 为 ViewCell 创建自定义渲染器

   using System;
   
   using Xamarin.Forms;
   using Xamarin.Forms.Platform.Android;
   
   using ListViewSample.Droid;
   
   [assembly: ExportRenderer(typeof(ViewCell), typeof(ViewCellItemSelectedCustomRenderer))]
   namespace ListViewSample.Droid
   {
       public class ViewCellItemSelectedCustomRenderer : ViewCellRenderer
       {
           protected override Android.Views.View GetCellCore(Cell item, Android.Views.View convertView, Android.Views.ViewGroup parent, Android.Content.Context context)
           {
               var cell = base.GetCellCore(item, convertView, parent, context);
   
               cell.SetBackgroundResource(Resource.Drawable.ViewCellBackground);
   
               return cell;
           }
       }
   }
   

编辑：删除了没有自定义渲染器的实现

---

示例 Xamarin.Forms ListView 应用

using System;
using System.Collections.Generic;

using Xamarin.Forms;

namespace ListViewSample
{
    public class CustomViewCell : ViewCell
    {
        public CustomViewCell()
        {
            View = new Label
            {
                Text = "Hello World"
            };
        }
    }

    public class ListViewContentPage : ContentPage
    {
        public ListViewContentPage()
        {
            var itemSourceList = new List<CustomViewCell>();
            itemSourceList.Add(new CustomViewCell());
            itemSourceList.Add(new CustomViewCell());

            var listView = new ListView();
            listView.ItemTemplate = new DataTemplate(typeof(CustomViewCell));
            listView.ItemsSource = itemSourceList;
            listView.SeparatorVisibility = SeparatorVisibility.None;

            Content = listView;
        }
    }

    public class App : Application
    {
        public App()
        {
            // The root page of your application

            MainPage = new NavigationPage(new ListViewContentPage());
        }
    }
}