<Window x:Class="ProgressBar.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:ProgressBar"
    mc:Ignorable="d"
    Title="MainWindow" Height="250" Width="400">
  <Grid>
    <ProgressBar Name="progressBar" Minimum="1" Maximum="1000" Height="50"/>
    <Button Content="Done" VerticalAlignment="Bottom" HorizontalAlignment="Center" FontSize="20" Margin="10" Click="Button_Click"/>
  </Grid>
</Window>

using System;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Threading;
 
namespace ProgressBar
{
  /// <summary>
  /// MainWindow.xaml 的交互邏輯
  /// </summary>
  public partial class MainWindow : Window
  {
    public MainWindow()
    {
      InitializeComponent();
    }
 
    private delegate void UpdateProgressBarDelegate(DependencyProperty dp, object value);
 
    private void Button_Click(object sender, RoutedEventArgs e)
    {
      UpdateProgressBarDelegate updateProgressBaDelegate = new UpdateProgressBarDelegate(progressBar.SetValue);
      for (int i = (int)progressBar.Minimum; i <= (int)progressBar.Maximum; i++)
      {
        Dispatcher.Invoke(updateProgressBaDelegate, DispatcherPriority.Background, new object[] { RangeBase.ValueProperty, Convert.ToDouble(i) });
      }
    }
  }
}