Xamarin表单触发器不工作自定义渲染器

我有extendedentry和自定义渲染器类

public class ExtendedEntryRenderer : EntryRenderer
{
    protected override void OnElementChanged(ElementChangedEventArgs<Entry> e)
    {
        base.OnElementChanged(e);

        if (Control != null)
        {
            Control.Click += (sender, evt) =>
            {
                var nativeEditText = (global::Android.Widget.EditText)Control;
                nativeEditText.SetSelectAllOnFocus(true);

                new Handler().PostDelayed(delegate
                {
                     Control.InputType = 0;
                     try
                     {
                         InputMethodManager inputMethodManager = Control.Context.GetSystemService(Android.Content.Context.InputMethodService) as InputMethodManager;
                         if (inputMethodManager != null)
                         {
                             inputMethodManager.HideSoftInputFromWindow(Control.WindowToken, HideSoftInputFlags.None);
                         }
                     }
                     catch (Exception Ex)
                     {

                     }
                 }, 300L);
            };


            // Hide soft input keyboard
            Control.FocusChange += (sender, evt) =>
            {
                // Select all on entry focus
                var nativeEditText = (global::Android.Widget.EditText)Control;

                nativeEditText.SetSelectAllOnFocus(true);

                new Handler().PostDelayed(delegate
                 {
                     Control.InputType = 0;
                     try
                     {
                         InputMethodManager inputMethodManager = Control.Context.GetSystemService(Android.Content.Context.InputMethodService) as InputMethodManager;
                         if (inputMethodManager != null)
                         {
                            inputMethodManager.HideSoftInputFromWindow(Control.WindowToken, HideSoftInputFlags.None);
                         }
                     }
                     catch (Exception Ex)
                     {

                     }
                 }, 300L);
            };
        }
    }
}

我的自定义条目：

public class ExtendedEntry : Entry
{

}

我的XAML文件是这样的：

<local:ExtendedEntry x:Name="BarcodeEntry" Text="{Binding Barcode}" Margin="0,0,0,0" HorizontalOptions="FillAndExpand" VerticalOptions="Start">
    <Entry.Triggers>
        <Trigger TargetType="Entry" Property="IsFocused" Value="True">
            <Setter Property="BackgroundColor" Value="Yellow" />
            <Setter Property="TextColor" Value="Black" />
        </Trigger>
    </Entry.Triggers>       
</local:ExtendedEntry>

Trigger 不起作用 .

但是，当我更改为默认输入控件时，如下所示：

<Entry x:Name="BarcodeEntry" Text="{Binding Barcode}" Margin="0,0,0,0"HorizontalOptions="FillAndExpand" VerticalOptions="Start">
    <Entry.Triggers>
        <Trigger TargetType="Entry" Property="IsFocused" Value="True">
            <Setter Property="BackgroundColor" Value="Yellow" />
            <Setter Property="TextColor" Value="Black" />
        </Trigger>
    </Entry.Triggers>       
</Entry>

Trigger 有效 .

我错了什么？

Edit

来自Xamarin.Forms的 ExportRenderer 行在我的渲染器类中 .

[assembly: ExportRenderer(typeof(ExtendedEntry), typeof(ExtendedEntryRenderer))]