xamarin viewmodel w kontrolce

Question

Mam taki kod:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace App6.Controls
{
        public class ImageButtonViewModel : INotifyPropertyChanged
        {
            public event PropertyChangedEventHandler PropertyChanged;
            private bool _Enable { get; set; }
            public bool Enable
            {
                get => _Enable;
                set
                {
                    _Enable = value;
                    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Enable)));
                }
            }
        }
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class ImageButton : Grid
    {

        public static readonly BindableProperty SourceProperty =
            BindableProperty.Create("Source", typeof(string), typeof(ImageButton));
        public string Source
        {
            get { return (string)GetValue(SourceProperty); }
            set { SetValue(SourceProperty, value); }
        }

        public static readonly BindableProperty ClickCommandProperty =
            BindableProperty.Create("ClickCommand", typeof(ICommand), typeof(ImageButton));
        public ICommand ClickCommand
        {
            get { return (ICommand)GetValue(ClickCommandProperty); }
            set { SetValue(ClickCommandProperty, value); }
        }

        public ImageButton()
        {
            InitializeComponent();
            //this.BindingContext = new ImageButtonViewModel();   //// to powoduje blad
        }

        protected override void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            if (propertyName == ClickCommandProperty.PropertyName)
            {
                ClickCommand.CanExecuteChanged += (s, e) =>
                {
                    (this.BindingContext as ImageButtonViewModel).Enable = ClickCommand.CanExecute(null);
                };
            }
            base.OnPropertyChanged(propertyName);

        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<Grid xmlns="http://xamarin.com/schemas/2014/forms" 
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="App6.Controls.ImageButton"
             xmlns:vm="clr-namespace:App6.Controls"
             xmlns:controls="clr-namespace:App6.Controls"
             x:Name="this">
    <!--To powoduje blad-->
    <!--<Grid.BindingContext>
        <controls:ImageButtonViewModel />
    </Grid.BindingContext>-->
    <Button x:Name="B1" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand" Command="{Binding Source={x:Reference this}, Path=ClickCommand}" />
    <Image x:Name="B2" VerticalOptions="Center" HorizontalOptions="Center" Source="{Binding Source, Source={x:Reference this}}"  Aspect="AspectFit" Margin="30" >
        <Image.GestureRecognizers>
            <TapGestureRecognizer Command="{Binding Source={x:Reference this}, Path=ClickCommand}" />
        </Image.GestureRecognizers>
    </Image>
</Grid>

View model nie jest nigdzie wykorzystywane, ale dodanie go do kodu poprzez xaml lub w c# psuje z jakiegoś powodu działanie kontrolki. Nie reaguje wtedy na ClickCommand. Czym jest to spowodowane i jak prawidłowo dodać viewmodel?

Answer 1

Próbowałeś dodać konstruktor do ViewModelu?

Comments

Po co?