• xmal 代码

<Window x:Class="ThreadTest.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:ThreadTest"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="41,20,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
        <DataGrid AutoGenerateColumns="False" Height="99" HorizontalAlignment="Left" Margin="40,70,0,0" Name="dataGrid1" VerticalAlignment="Top" Width="441" />
        <Canvas Name="loading" RenderTransformOrigin="0.5,0.5" Visibility="Collapsed" HorizontalAlignment="Center" VerticalAlignment="Center" Width="120" Height="120" Margin="187,76,241,85">
            <Ellipse Width="15" Height="15" Canvas.Left="55" Canvas.Top="31" Stretch="Fill" Fill="#FFD1D1F7" Opacity="1.0"/>
            <Ellipse Width="15" Height="15" Canvas.Left="38" Canvas.Top="39" Stretch="Fill" Fill="Blue" Opacity="0.8"/>
            <Ellipse Width="15" Height="15" Canvas.Left="36" Canvas.Top="58" Stretch="Fill" Fill="#FF0000FE" Opacity="0.7"/>
            <Ellipse Width="15" Height="15" Canvas.Left="52" Canvas.Top="67" Stretch="Fill" Fill="Blue" Opacity="0.6"/>
            <Ellipse Width="15" Height="15" Canvas.Left="68" Canvas.Top="61" Stretch="Fill" Fill="#FF2E2EFF" Opacity="0.5"/>
            <Ellipse Width="15" Height="15" Canvas.Left="69" Canvas.Top="42" Stretch="Fill" Fill="#FF6F6FFF" Opacity="0.4"/>
            <Canvas.RenderTransform>
                <RotateTransform x:Name="SpinnerRotate" Angle="0" />
            </Canvas.RenderTransform>
            <Canvas.Triggers>
                <EventTrigger RoutedEvent="ContentControl.Loaded">
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetName="SpinnerRotate" Storyboard.TargetProperty="(RotateTransform.Angle)" From="0" To="360" Duration="0:0:0.8" RepeatBehavior="Forever" />
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Canvas.Triggers>
        </Canvas>
        <Label Name="lab_pro" Content="Label" Height="28" Margin="140,14,315,239" />
    </Grid>
</Window>

• 后台代码:

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.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Threading;

namespace ThreadTest
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {

        public MainWindow()
        {
            InitializeComponent();
        }

        BackgroundWorker bgMeet;
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            bgMeet = new BackgroundWorker();
            bgMeet.WorkerReportsProgress = true;
            bgMeet.DoWork += new DoWorkEventHandler(bgMeet_DoWork);
            bgMeet.ProgressChanged += new ProgressChangedEventHandler(bgMeet_ProgressChanged);
            bgMeet.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgMeet_RunWorkerCompleted);
            bgMeet.RunWorkerAsync();
        }
        void bgMeet_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            loading.Visibility = System.Windows.Visibility.Collapsed;
            this.Dispatcher.Invoke(new Action(() =>
            {
                this.lab_pro.Content = "完成";
            }));
        }
        void bgMeet_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            this.Dispatcher.Invoke(new Action(() =>
            {
                this.lab_pro.Content = e.ProgressPercentage;
            }));
        }

        void bgMeet_DoWork(object sender, DoWorkEventArgs e)
        {
            this.Dispatcher.Invoke(new Action(() =>
            {
                loading.Visibility = System.Windows.Visibility.Visible;
            }));
            GetData();
        }
        public void GetData()
        {
            for (int i = 0; i < 11; i++)
            {
                bgMeet.ReportProgress(i);
                System.Threading.Thread.Sleep(500);
            }
        }
    }
}

参考；
1 WPF防止界面卡死并显示加载中效果
2 BackgroundWorker原理剖析