可重用的xamarin控件提供“无法强制转换类型为‘xamarin.forms.xaml.memode’的对象”.

Question

我是一个新手类型的编码器，这是我第一次尝试在Xamarin.Forms中使用可重用控件(实际上也是我在所有编程中的第一次尝试)。在研究中，我发现它说我在给一个事件赋值.我很确定代码的哪一部分-- means...but --我不知道该怎么做才能使它正确。我正在尝试制作一个带有标签的ImageCircle，这个标签是一个可重用的控件。

我的Xaml：

       <?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms" 
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:controls="clr-namespace:ImageCircle.Forms.Plugin.Abstractions;assembly=ImageCircle.Forms.Plugin"
         x:Class="MyApp.View.Templates.CircleImageButton"
         x:Name="this">
 <ContentView.Content>
    <StackLayout Margin="{StaticResource Margin}" Padding="{StaticResource Padding}" Spacing="0" Grid.Row="{Binding Source={x:Reference this}, Path=GridRow}" Grid.Column="{Binding Source={x:Reference this}, Path=GridColumn}">
        <controls:CircleImage Source="{Binding Source={x:Reference this}, Path=Image}" FillColor="Green" Aspect="AspectFill" Margin="{StaticResource Margin}" >

            <!--error is believed to be caused here-->
<controls:CircleImage.GestureRecognizers>
                <TapGestureRecognizer Tapped="{Binding Source={x:Reference this}, Path=TapGestureCommand}" />
            </controls:CircleImage.GestureRecognizers>

            <controls:CircleImage.WidthRequest>
                <OnPlatform x:TypeArguments="x:Double">
                    <On Platform="Android, iOS">40</On>
                    <On Platform="WinPhone">75</On>
                </OnPlatform>
            </controls:CircleImage.WidthRequest>
            <controls:CircleImage.HeightRequest>
                <OnPlatform x:TypeArguments="x:Double">
                    <On Platform="Android, iOS">40</On>
                    <On Platform="WinPhone">75</On>
                </OnPlatform>
            </controls:CircleImage.HeightRequest>
        </controls:CircleImage>
        <Label Text="{Binding Source={x:Reference this}, Path=LabelCaption}"/>
    </StackLayout>
  </ContentView.Content>
</ContentView>

我的代码背后是：

    using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace MyApp.View.Templates
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class CircleImageButton : ContentView
{
    public static readonly BindableProperty ImageProperty = BindableProperty.Create("Image", typeof(string), typeof(CircleImageButton), string.Empty);
    public static readonly BindableProperty GridRowProperty = BindableProperty.Create("GridRow", typeof(int), typeof(CircleImageButton), default(int));
    public static readonly BindableProperty GridColumnProperty = BindableProperty.Create("GridColumn", typeof(int), typeof(CircleImageButton), default(int));
    public static readonly BindableProperty LabelCaptionProperty = BindableProperty.Create("LabelCaption", typeof(string), typeof(CircleImageButton), string.Empty);
    public static readonly BindableProperty TapGestureCommandProperty = BindableProperty.Create("TapGestureCommand", typeof(string), typeof(CircleImageButton), string.Empty);

    public string Image
    {
        get { return (string)GetValue(ImageProperty); }
        set { SetValue(ImageProperty, value); }
    }

    public int GridRow
    {
        get { return (int)GetValue(GridRowProperty); }
        set { SetValue(GridRowProperty, value); }
    }
    public int GridColumn
    {
        get { return (int)GetValue(GridColumnProperty); }
        set { SetValue(GridColumnProperty, value); }
    }
    public string LabelCaption
    {
        get { return (string)GetValue(LabelCaptionProperty); }
        set { SetValue(LabelCaptionProperty, value); }
    }
    public string TapGestureCommand
    {
        get { return (string)GetValue(TapGestureCommandProperty); }
        set { SetValue(TapGestureCommandProperty, value); }
    }

    public CircleImageButton ()
    {
        InitializeComponent ();
    }
}
}

我很感激你的帮助，如果你有更好的方法来做这件事，请告诉我。我是来学习的。

Answer 1

<controls:CircleImage.GestureRecognizers>
                <TapGestureRecognizer Command="{Binding Source={x:Reference this}, Path=TapGestureCommand}" />
            </controls:CircleImage.GestureRecognizers>

在XAML中使用命令来绑定而不是点击事件。