WPF_Practice/PacticeSolution/ProgressBarMVVMSample/ViewModel/MainViewModel.cs

using ProgressBarMVVMSample.Command;
using ProgressBarMVVMSample.Model;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;

namespace ProgressBarMVVMSample.ViewModel
{
    internal class MainViewModel : BindableBase
    {
        private BackgroundWorker _worker;

        private ICommand _startWorkCommand;

        private string _title = "Progress bar MVVM Pattern";
        private int _currentProgress;
        private bool _progressVisibility;

        public string Title
        {
            get { return _title; }
            set { SetProperty(ref _title, value); }
        }

        public ICommand StartWorkCommand
        {
            get 
            {
                Predicate<object> canExecute = (param) =>
                {
                    if (_worker == null)
                        return false;

                    if (_worker.IsBusy)
                        MessageBox.Show("Background worker is busy.");

                    return !_worker.IsBusy;
                };

                return _startWorkCommand ?? (_startWorkCommand = new DelegateCommand(_worker.RunWorkerAsync, canExecute)); 
            }
        }

        public int CurrentProgress
        {
            get { return _currentProgress; }
            set { SetProperty(ref _currentProgress, value); }
        }

        public bool ProgressVisibility
        {
            get { return _progressVisibility; }
            set { SetProperty(ref _progressVisibility, value); }
        }

        public MainViewModel()
        {
            InitProgressBar();
        }

        private void InitProgressBar()
        {
            _worker = new BackgroundWorker();
            _worker.DoWork += DoWork;
            _worker.WorkerReportsProgress = true;
            _worker.ProgressChanged += ProgressChanged;

            this.ProgressVisibility = false;
        }

        private void ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            this.CurrentProgress = e.ProgressPercentage;
            if (this.CurrentProgress == 100)
                this.ProgressVisibility = false;
        }

        private void DoWork(object sender, DoWorkEventArgs e)
        {
            this.ProgressVisibility = true;
            for (int i = 0; i <= 100; i++)
            {
                Thread.Sleep(50);
                (sender as BackgroundWorker).ReportProgress(i);
            }

            this.ProgressVisibility = false;
        }
    }
}