MvvmDemo/MVVMDemo/MainViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;

namespace MVVMDemo
{
    public class MainViewModel : BaseViewModel
    {
        private string _textContent = "Default Content";
        public string TextContent { get => _textContent; set => UpdateProperty(ref _textContent, value); }

        public ICommand BtnCmd { get; private set; }

        public MainViewModel()
        {
            BtnCmd = new RelayCommand((_) =>
            {
                //这个就是控制是否启用的条件
                return string.IsNullOrEmpty(TextContent);
            }, (o) =>
            {
                // 获取CommandParameter绑定对象
                //var view = o as Window;//因为MainWindow继承自Window，所以可以这么写
                var view = o as MainWindow;
                //举个例子： 点击就最大化窗口
                if (view != null)
                    view.WindowState = WindowState.Maximized;

                TextContent = "Default Content";
            });
        }
    }
}