Xamarin，有什么方法可以水平使用listview吗? [英] Xamarin, Is there any way a listview can be used horizontally?

问题描述

我想使用列表视图将用户控件水平显示为项目.因此，有什么方法可以水平显示列表视图.

I want to use a listview to display an user control as item horizontally. So is there any way we can display a listview horizontally.

推荐答案

您可以通过自定义控件"实现水平列表视图". 请参阅此代码，

You can achieve Horizontal Listview by Custom Control. Kindly Refer this Code,

1)扩展渲染视图列表的Scrollview属性

using System;
using System.Collections;
using System.Collections.Generic;
using System.Windows.Input;
using Xamarin.Forms;
namespace ProjectName.CustomControls
{
public class HorizontalListview : ScrollView
    {
        public static readonly BindableProperty ItemsSourceProperty =
            BindableProperty.Create("ItemsSource", typeof(IEnumerable), typeof(HorizontalListview), default(IEnumerable));

        public IEnumerable ItemsSource
        {
            get { return (IEnumerable)GetValue(ItemsSourceProperty); }
            set { SetValue(ItemsSourceProperty, value); }
        }

        public static readonly BindableProperty ItemTemplateProperty =
            BindableProperty.Create("ItemTemplate", typeof(DataTemplate), typeof(HorizontalListview), default(DataTemplate));

        public DataTemplate ItemTemplate
        {
            get { return (DataTemplate)GetValue(ItemTemplateProperty); }
            set { SetValue(ItemTemplateProperty, value); }
        }

        public event EventHandler<ItemTappedEventArgs> ItemSelected;

        public static readonly BindableProperty SelectedCommandProperty =
            BindableProperty.Create("SelectedCommand", typeof(ICommand), typeof(HorizontalListview), null);

        public ICommand SelectedCommand
        {
            get { return (ICommand)GetValue(SelectedCommandProperty); }
            set { SetValue(SelectedCommandProperty, value); }
        }

        public static readonly BindableProperty SelectedCommandParameterProperty =
            BindableProperty.Create("SelectedCommandParameter", typeof(object), typeof(HorizontalListview), null);

        public object SelectedCommandParameter
        {
            get { return GetValue(SelectedCommandParameterProperty); }
            set { SetValue(SelectedCommandParameterProperty, value); }
        }


        public void Render()
        {
            if (ItemTemplate == null || ItemsSource == null)
                return;

            var layout = new StackLayout();
           layout.Spacing = 0;

            layout.Orientation = Orientation == ScrollOrientation.Vertical ? StackOrientation.Vertical : StackOrientation.Horizontal;

            foreach (var item in ItemsSource)
            {
                var command = SelectedCommand ?? new Command((obj) =>
                {
                    var args = new ItemTappedEventArgs(ItemsSource, item);
                    ItemSelected?.Invoke(this, args);
                });
                var commandParameter = SelectedCommandParameter ?? item;

                var viewCell = ItemTemplate.CreateContent() as ViewCell;
                viewCell.View.BindingContext = item;
                viewCell.View.GestureRecognizers.Add(new TapGestureRecognizer
                {
                    Command = command,
                    CommandParameter = commandParameter,
                    NumberOfTapsRequired = 1
                });
                layout.Children.Add(viewCell.View);
            }

            Content = layout;
        }
    }

2)在XAML页面中包括命名空间

xmlns:control="clr-namespace:ProjectName"

3)在设计中使用控件

  <control:HorizontalListview Orientation="Horizontal" x:Name="lst">                   
                    <control:HorizontalListview.ItemTemplate>
                        <DataTemplate>
                            <ViewCell>
                                <Label Style="{StaticResource lblPlaceNumberRing}" />
                            </ViewCell>
                        </DataTemplate>
                    </control:HorizontalListview.ItemTemplate>
                </control:HorizontalListview>

4)制作适用于Android的渲染器

using System;
using System.ComponentModel;
using ProjectName;
using ProjectName.Droid;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;


[assembly: ExportRenderer(typeof(HorizontalListview), typeof(HorizontalListviewRendererAndroid))]

namespace ProjectName.Droid.Renderers
{
    public class HorizontalListviewRendererAndroid : ScrollViewRenderer
    {
        protected override void OnElementChanged(VisualElementChangedEventArgs e)
        {
            base.OnElementChanged(e);

            var element = e.NewElement as HorizontalListview;
            element?.Render();

            if (e.OldElement != null)
                e.OldElement.PropertyChanged -= OnElementPropertyChanged;

            e.NewElement.PropertyChanged += OnElementPropertyChanged;

        }

        protected void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if (ChildCount > 0)
            {
                GetChildAt(0).HorizontalScrollBarEnabled = false;
                GetChildAt(0).VerticalScrollBarEnabled = false;
            }
        }
    }
}

5)制作iOS渲染器

using System;
using UIKit;
using ProjectName.iOS;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
using ProjectName;
using System.ComponentModel;

[assembly: ExportRenderer(typeof(HorizontalListview), typeof(HorizontalListviewRendererIos))]

namespace ProjectName.iOS.Renderers
{
    public class HorizontalListviewRendererIos : ScrollViewRenderer
    {
        protected override void OnElementChanged(VisualElementChangedEventArgs e)
        {
            base.OnElementChanged(e);

            var element = e.NewElement as HorizontalListview;
            element?.Render();
            if (e.OldElement != null)
                e.OldElement.PropertyChanged -= OnElementPropertyChanged;

            e.NewElement.PropertyChanged += OnElementPropertyChanged;
        }

        protected void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            this.ShowsHorizontalScrollIndicator = false;
            this.ShowsVerticalScrollIndicator = false;
            this.AlwaysBounceHorizontal = false;
            this.AlwaysBounceVertical = false;
            this.Bounces = false;

        }
       }
}

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