在 Xamarin 中自定义自定义选择器

Question

我希望每个人都做得很好。如果我在屏幕上的项目上释放鼠标，有人可以帮助我如何删除“取消”和“确定”按钮并允许/引发事件选择，其次我需要帮助更改边框和背景的颜色颜色？感谢您的帮助，谢谢。

选择器：

    public class BorderlessPickerRenderer : PickerRenderer
{
    public static void Init() { }
    protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
    {
        base.OnElementChanged(e);
        if (e.OldElement == null)
        {
            Control.Background = Android.Graphics.Color.Rgb();
            string fontFamily = e.NewElement?.FontFamily;
            
            var layoutParams = new MarginLayoutParams(Control.LayoutParameters);
            layoutParams.SetMargins(0, 0, 0, 0);
            LayoutParameters = layoutParams;
            Control.LayoutParameters = layoutParams;
            Control.SetPadding(0, 0, 0, 0);
             

            SetPadding(0, 0, 0, 0);
        }
    }
}

Answer 1

您可以使用 Custon Remderer 来定义自定义对话框。

如果我在屏幕上的项目上释放鼠标，如何删除“取消”和“确定”按钮并允许/引发事件选择，

AlertDialog 提供SetNegativeButton 事件来设置取消和确定按钮。在视图中删除两者就可以了。自定义视图是一个列表视图。您可以使用 ListView 的 ItemClick。

其次，我在更改边框颜色和背景颜色方面需要帮助？

您可以将对话框的背景颜色设置为更改。添加android:divider 设置边框颜色。并添加android:dividerHeight 设置边界高度。

自定义渲染器：

 [assembly: ExportRenderer(typeof(Picker), typeof(BorderlessPickerRenderer))]
namespace App15.Droid
{
 public class BorderlessPickerRenderer : PickerRenderer
 {
    AlertDialog listDialog;
    string[] items;
    public BorderlessPickerRenderer(Context context) : base(context)
    {
    }
    protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
    {
        base.OnElementChanged(e);
        if (Control != null)
        {
            Control.Click += Control_Click1; ;
        }
    }

    private void Control_Click1(object sender, EventArgs e)
    {
        Picker model = Element;
        items = model.Items.ToArray();
        AlertDialog.Builder builder = new AlertDialog.Builder(this.Context);
        builder.SetTitle(model.Title ?? "");
        //builder.SetNegativeButton("Cancel", (s, a) =>
        //{
        //    Control?.ClearFocus();
        //    builder = null;
        //});
        Android.Views.View view = LayoutInflater.From(this.Context).Inflate(Resource.Layout.listview, null);
        Android.Widget.ListView listView = view.FindViewById<Android.Widget.ListView>(Resource.Id.listView1);

        MyAdapter myAdapter = new MyAdapter(items, Element.SelectedIndex);
        listView.Adapter = myAdapter;
        listView.ItemClick += ListView_ItemClick;
        builder.SetView(view);
        listDialog = builder.Create();
        listDialog.Window.DecorView.SetBackgroundColor(Android.Graphics.Color.Pink); // set the dialog background color 
        listDialog.Show();
        //Android.Widget.Button button = listDialog.GetButton((int)DialogButtonType.Negative);
        //button.Text = "Cancel";
        //button.Click += Button_Click;
        //button.SetTextColor(Android.Graphics.Color.Blue); // set the button bottom color
    }
    //private void Button_Click(object sender, EventArgs e)
    //{
    //    listDialog.Dismiss();
    //    listDialog = null;
    //}
    private void ListView_ItemClick(object sender, AdapterView.ItemClickEventArgs e)
    {
        Control.Text = items[e.Position];
        Element.SelectedIndex = e.Position;
        Console.WriteLine(items[e.Position]);
        listDialog.Dismiss();
        listDialog = null;
    }
    class MyAdapter : BaseAdapter
    {
        private string[] items;
        private int selectedIndex;

        public MyAdapter(string[] items)
        {
            this.items = items;
        }

        public MyAdapter(string[] items, int selectedIndex) : this(items)
        {
            this.selectedIndex = selectedIndex;
        }

        public override int Count => items.Length;

        public override Java.Lang.Object GetItem(int position)
        {
            return items[position];
        }

        public override long GetItemId(int position)
        {
            return position;
        }

        public override Android.Views.View GetView(int position, Android.Views.View convertView, ViewGroup parent)
        {
            if (convertView == null)
            {
                convertView = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.listview_item, null);
            }
            TextView textView = convertView.FindViewById<TextView>(Resource.Id.textView1);
            textView.Text = items[position];
            return convertView;
        }
    }
  }
 }

Xaml：

    <Picker x:Name="picker"  Title="Title" VerticalOptions="CenterAndExpand" >
        <Picker.ItemsSource>
            <x:Array Type="{x:Type x:String}">
                <x:String>Option 1</x:String>
                <x:String>Option 2</x:String>
                <x:String>Option 3</x:String>
            </x:Array>
        </Picker.ItemsSource>
    </Picker>

listview.xml：您可以在 android 项目中创建 Resources/layout。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ListView
       android:id="@+id/listView1"
       android:divider="@android:color/holo_green_light"
        android:dividerHeight="2dp"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"/>


</LinearLayout>

listview_item.xml ：您可以在您的Resources/layout android 项目中创建。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
   <TextView
      android:id="@+id/textView1"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"/>
</LinearLayout>