MVVM綁定 填坑，必須在與 DependencyObject 相同的線程上創建 DependencySource

場景：線程裏面構建MVVM實體類，實體類包含 Brush 屬性時，構建 SolidColorBrush 需要UI線程，否則會報 “必須在與 DependencyObject 相同的線程上創建 DependencySource”

MVVM實體類

 1 using System;
 2 using System.Collections.Generic;
 3 using System.ComponentModel;
 4 using System.Linq;
 5 using System.Text;
 6 using System.Threading.Tasks;
 7 using System.Windows.Media;
 8 
 9 namespace WpfApp3
10 {
11     public class TestInfo : INotifyPropertyChanged
12     {
13         public event PropertyChangedEventHandler PropertyChanged;
14 
15         public Brush BG { get; set; }
16     }
17 }

下面是報錯代碼：

 1 <Window x:Class="WpfApp3.MainWindow"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 5         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 6         xmlns:local="clr-namespace:WpfApp3"
 7         mc:Ignorable="d"
 8         Title="MainWindow" Height="450" Width="800">
 9     <Grid Background="{Binding BG}">
10         
11     </Grid>
12 </Window>

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 using System.Windows.Controls;
 8 using System.Windows.Data;
 9 using System.Windows.Documents;
10 using System.Windows.Input;
11 using System.Windows.Media;
12 using System.Windows.Media.Imaging;
13 using System.Windows.Navigation;
14 using System.Windows.Shapes;
15 
16 namespace WpfApp3
17 {
18     /// <summary>
19     /// MainWindow.xaml 的交互邏輯
20     /// </summary>
21     public partial class MainWindow : Window
22     {
23         public MainWindow()
24         {
25             InitializeComponent();
26 
27             Loaded += MainWindow_Loaded;
28         }
29 
30         private async void MainWindow_Loaded(object sender, RoutedEventArgs e)
31         {
32             TestInfo info = new TestInfo();
33             await Task.Run(() =>
34             {
35                 info.BG = new SolidColorBrush(Colors.Red);
36             });
37             this.DataContext = info;
38         }
39     }
40 }

原因：

因爲  info.BG = new SolidColorBrush(Colors.Red);  這行報錯，原因是 構建 SolidColorBrush 需要UI 線程！！

調整後的後端代碼：

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Windows;
 7 using System.Windows.Controls;
 8 using System.Windows.Data;
 9 using System.Windows.Documents;
10 using System.Windows.Input;
11 using System.Windows.Media;
12 using System.Windows.Media.Imaging;
13 using System.Windows.Navigation;
14 using System.Windows.Shapes;
15 
16 namespace WpfApp3
17 {
18     /// <summary>
19     /// MainWindow.xaml 的交互邏輯
20     /// </summary>
21     public partial class MainWindow : Window
22     {
23         public MainWindow()
24         {
25             InitializeComponent();
26 
27             Loaded += MainWindow_Loaded;
28         }
29 
30         private async void MainWindow_Loaded(object sender, RoutedEventArgs e)
31         {
32             TestInfo info = new TestInfo();
33             await Task.Run(() =>
34             {
35                 Brush brush = null;
36                 Dispatcher.Invoke(() =>
37                 {
38                     brush = new SolidColorBrush(Colors.Red);
39                 });
40                 info.BG = brush;
41             });
42             this.DataContext = info;
43         }
44     }
45 }