Avalonia 中的生命周期

总目录

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前言

本文通过实际的案例来理解Avalonia中的生命周期，通过理解Avalonia中的生命周期可以帮助我们在合适的时间实行特定的逻辑，如资源的初始化与清理、用户交互的处理等。

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一、Window生命周期

1. 先容

Window的生命周期是指Window从创建到销毁的整个过程，包括初始化、表现、激活、关闭等状态。
2. 案例

下面 通过一个案例来说明Window的生命周期：MainWindow中 点击按钮，弹出Window1窗口，然后通过Window1的关闭按钮来关闭Window1来展示完备的Window生命周期

• 创建Avalonia .NET MVVM App(AvaloniaUI)项目，MVVMToolKit 选择 CommunityToolKit
  
• MainWindow.axaml
  

1. <Window xmlns="https://github.com/avaloniaui"
2.         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
3.         xmlns:vm="using:AvaloniaWindowDemo.ViewModels"
4.         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
5.         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
6.         mc:Ignorable="d" d:DesignWidth="400" d:DesignHeight="250"
7.         x:Class="AvaloniaWindowDemo.Views.MainWindow"
8.         xmlns:v="using:AvaloniaWindowDemo.Views"
9.         x:DataType="vm:MainWindowViewModel"
10.         Icon="/Assets/avalonia-logo.ico"
11.         Title="AvaloniaWindowDemo">
12.     <Design.DataContext>
13.         <vm:MainWindowViewModel />
14.     </Design.DataContext>
15.     <Grid Margin="50" Background="Red">
16.                 <Button x:Name="testButton" VerticalAlignment="Center" HorizontalAlignment="Center" Content="Test" Click="Button_Click"></Button>
17.         </Grid>
18. </Window>

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• MainWindow.axaml.cs
  

1.         private void Button_Click(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
2.         {
3.             new Window1().Show();
4.         }

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• Window1.axaml
  

1. <Window xmlns="https://github.com/avaloniaui"
2.         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
3.         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
4.         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
5.         mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
6.         x:Class="AvaloniaWindowDemo.Window1"
7.         Title="Window1">
8.   Welcome to Avalonia!
9. </Window>

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• Window1.axaml.cs
  

1. public partial class Window1 : Window
2. {
3.     public Window1()
4.     {
5.         InitializeComponent();
6.         Debug.WriteLine("InitializeComponent 初始化");
7.         this.Initialized += Window1_Initialized;
8.         
9.         this.AttachedToVisualTree += Window1_AttachedToVisualTree;
10.         this.AttachedToLogicalTree += Window1_AttachedToLogicalTree;
11.         this.DetachedFromVisualTree += Window1_DetachedFromVisualTree;
12.         this.DetachedFromLogicalTree += Window1_DetachedFromLogicalTree;
14.         this.Loaded += Window1_Loaded;
15.         this.Opened += Window1_Opened;
16.         this.Activated += Window1_Activated;
17.         this.Deactivated += Window1_Deactivated;
18.         this.Closing += Window1_Closing;
19.         this.Closed += Window1_Closed;
20.     }
22.     private void Window1_DetachedFromLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
23.     {
24.         Debug.WriteLine("Window1_DetachedFromLogicalTree");
25.     }
27.     private void Window1_DetachedFromVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
28.     {
29.         Debug.WriteLine("Window1_DetachedFromVisualTree");
30.     }
32.     private void Window1_Initialized(object? sender, System.EventArgs e)
33.     {
34.         Debug.WriteLine("Window1_Initialized");
35.     }
37.     private void Window1_Closed(object? sender, System.EventArgs e)
38.     {
39.         Debug.WriteLine("Window1_Closed");
40.     }
42.     private void Window1_Closing(object? sender, WindowClosingEventArgs e)
43.     {
44.         Debug.WriteLine("Window1_Closing");
45.     }
47.     private void Window1_Deactivated(object? sender, System.EventArgs e)
48.     {
49.         Debug.WriteLine("Window1_Deactivated");
50.     }
52.     private void Window1_Activated(object? sender, System.EventArgs e)
53.     {
54.         Debug.WriteLine("Window1_Activated");
55.     }
57.     private void Window1_Opened(object? sender, System.EventArgs e)
58.     {
59.         Debug.WriteLine("Window1_Opened");
60.     }
62.     private void Window1_Loaded(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
63.     {
64.         Debug.WriteLine("Window1_Loaded");
65.     }
67.     private void Window1_AttachedToLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
68.     {
69.         Debug.WriteLine("Window1_AttachedToLogicalTree");
70.     }
72.     private void Window1_AttachedToVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
73.     {
74.         Debug.WriteLine("Window1_AttachedToLogicalTree");
75.     }
76. }

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当点击 按钮 Show 出 Window1 时：

当点击Window1 的关闭按钮 时：

3. 小结

一个Window 的生命周期：

• 创建周期：
  
  
  
  • 初始化（ InitializeComponent ）
    
  • 激活（Activated）
    
  • 打开界面（Opened）
    
  • 加载完成（Loaded）
    
  
  
• 销毁周期：
  
  
  
  • 激活（Activated）
    
  • 关闭中（Closing）
    
  • 失活（Deactivated）
    
  • 从逻辑树分离（DetachedFromLogicalTree）
    
  • 从视觉树分离（DetachedFromVisualTree）
    
  • 关闭（Closed）
    
  
  

   理解生命周期的时间点，我们可以对应在生命周期 进行 一些初始化，更新UI状态，释放资源，实行资源接纳等操作。
  二、Avalonia 控件的生命周期

1. 先容

Avalonia 中 如 TextBox，TextBlock ，Button 等控件也有着本身的生命周期，控件的生命周期重要表现在附加到视觉树和从视觉树分离上。
2. 案例

• MainWindow
  
  
  
  • 作用：点击按钮 弹出 Window1 窗口
    
  
  

1. <Window xmlns="https://github.com/avaloniaui"
2.         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
3.         xmlns:vm="using:AvaloniaWindowDemo.ViewModels"
4.         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
5.         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
6.         mc:Ignorable="d" d:DesignWidth="400" d:DesignHeight="250"
7.         x:Class="AvaloniaWindowDemo.Views.MainWindow"
8.         xmlns:v="using:AvaloniaWindowDemo.Views"
9.         x:DataType="vm:MainWindowViewModel"
10.         Icon="/Assets/avalonia-logo.ico"
11.         Title="AvaloniaWindowDemo">
12.     <Design.DataContext>
13.         <vm:MainWindowViewModel />
14.     </Design.DataContext>
15.     <Grid Margin="50" Background="Red">
16.                 <Button x:Name="testButton" VerticalAlignment="Center" HorizontalAlignment="Center" Content="Test" Click="Button_Click"></Button>
17.         </Grid>
18. </Window>

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1.         private void Button_Click(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
2.         {
3.             new Window1().Show();
4.         }

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• Window1
  
  
  
  • 作用：通过弹出的Window1 观察Window1的生命周期 和 Window1内 Button 和 UserControl的生命周期
    
  
  

1. <Window xmlns="https://github.com/avaloniaui"
2.         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
3.         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
4.         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
5.         mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
6.         x:Class="AvaloniaWindowDemo.Window1"
7.                 xmlns:v="using:AvaloniaWindowDemo.Views"
8.         Title="Window1">
9.         <StackPanel Background="Azure">
10.                 <Button x:Name="Button1" Content="Show" HorizontalAlignment="Center"></Button>
11.                 <v:UserControl1 x:Name="UserControl1" Height="60"></v:UserControl1>
12.         </StackPanel>
13. </Window>

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1. public partial class Window1 : Window
2. {
3.     public Window1()
4.     {
5.         InitializeComponent();
6.         Debug.WriteLine("InitializeComponent 初始化");
7.         this.Initialized += Window1_Initialized;
8.         
9.         this.AttachedToVisualTree += Window1_AttachedToVisualTree;
10.         this.AttachedToLogicalTree += Window1_AttachedToLogicalTree;
11.         this.DetachedFromVisualTree += Window1_DetachedFromVisualTree;
12.         this.DetachedFromLogicalTree += Window1_DetachedFromLogicalTree;
14.         this.Loaded += Window1_Loaded;
15.         this.Opened += Window1_Opened;
16.         this.Activated += Window1_Activated;
17.         this.Deactivated += Window1_Deactivated;
18.         this.Closing += Window1_Closing;
19.         this.Closed += Window1_Closed;
21.         this.Button1.Initialized += Button1_Initialized;
22.         this.Button1.AttachedToVisualTree += Button1_AttachedToVisualTree;
23.         this.Button1.AttachedToLogicalTree += Button1_AttachedToLogicalTree;
24.         this.Button1.DetachedFromVisualTree += Button1_DetachedFromVisualTree;
25.         this.Button1.DetachedFromLogicalTree += Button1_DetachedFromLogicalTree;
27.         this.UserControl1.Initialized += UserControl1_Initialized;
28.         this.UserControl1.Loaded += UserControl1_Loaded;
29.         this.UserControl1.AttachedToVisualTree += UserControl1_AttachedToVisualTree;
30.         this.UserControl1.AttachedToLogicalTree += UserControl1_AttachedToLogicalTree;
31.         this.UserControl1.DetachedFromVisualTree += UserControl1_DetachedFromVisualTree;
32.         this.UserControl1.DetachedFromLogicalTree += UserControl1_DetachedFromLogicalTree;
33.     }
35.     private void UserControl1_Initialized(object? sender, System.EventArgs e)
36.     {
37.         Debug.WriteLine("UserControl1_Initialized");
38.     }
40.     private void UserControl1_DetachedFromLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
41.     {
42.         Debug.WriteLine("UserControl1_DetachedFromLogicalTree");
43.     }
45.     private void UserControl1_DetachedFromVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
46.     {
47.         Debug.WriteLine("UserControl1_DetachedFromVisualTree");
48.     }
50.     private void UserControl1_AttachedToVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
51.     {
52.         Debug.WriteLine("UserControl1_AttachedToVisualTree");
53.     }
55.     private void UserControl1_AttachedToLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
56.     {
57.         Debug.WriteLine("UserControl1_AttachedToLogicalTree");
58.     }
60.     private void UserControl1_Loaded(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
61.     {
62.         Debug.WriteLine("UserControl1_Loaded");
63.     }
65.     private void Button1_Loaded(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
66.     {
67.         Debug.WriteLine("Button1_Loaded");
68.     }
70.     private void Button1_DetachedFromLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
71.     {
72.         Debug.WriteLine("Button1_DetachedFromLogicalTree");
73.     }
75.     private void Button1_DetachedFromVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
76.     {
77.         Debug.WriteLine("Button1_DetachedFromVisualTree");
78.     }
80.     private void Button1_AttachedToLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
81.     {
82.         Debug.WriteLine("Button1_AttachedToLogicalTree");
83.     }
85.     private void Button1_AttachedToVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
86.     {
87.         Debug.WriteLine("Button1_AttachedToVisualTree");
88.     }
90.     private void Button1_Initialized(object? sender, System.EventArgs e)
91.     {
92.         Debug.WriteLine("Button1_Initialized");
93.     }
95.     private void Window1_DetachedFromLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
96.     {
97.         Debug.WriteLine("Window1_DetachedFromLogicalTree");
98.     }
100.     private void Window1_DetachedFromVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
101.     {
102.         Debug.WriteLine("Window1_DetachedFromVisualTree");
103.     }
105.     private void Window1_Initialized(object? sender, System.EventArgs e)
106.     {
107.         Debug.WriteLine("Window1_Initialized");
108.     }
110.     private void Window1_Closed(object? sender, System.EventArgs e)
111.     {
112.         Debug.WriteLine("Window1_Closed");
113.     }
115.     private void Window1_Closing(object? sender, WindowClosingEventArgs e)
116.     {
117.         Debug.WriteLine("Window1_Closing");
118.     }
120.     private void Window1_Deactivated(object? sender, System.EventArgs e)
121.     {
122.         Debug.WriteLine("Window1_Deactivated");
123.     }
125.     private void Window1_Activated(object? sender, System.EventArgs e)
126.     {
127.         Debug.WriteLine("Window1_Activated");
128.     }
130.     private void Window1_Opened(object? sender, System.EventArgs e)
131.     {
132.         Debug.WriteLine("Window1_Opened");
133.     }
135.     private void Window1_Loaded(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
136.     {
137.         Debug.WriteLine("Window1_Loaded");
138.     }
140.     private void Window1_AttachedToLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
141.     {
142.         Debug.WriteLine("Window1_AttachedToLogicalTree");
143.     }
145.     private void Window1_AttachedToVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
146.     {
147.         Debug.WriteLine("Window1_AttachedToLogicalTree");
148.     }
149. }

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• UserControl1
  
  
  
  • 通过UserControl 观察UserControl 内部TextBlock 的生命周期
    
  
  

1. <UserControl xmlns="https://github.com/avaloniaui"
2.              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
3.              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
4.              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
5.              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
6.              x:Class="AvaloniaWindowDemo.Views.UserControl1">
7.     <Border Background="Aqua">
8.         <TextBlock x:Name="UserControl_TextBlock" Text="这是一个UserControl"></TextBlock>
9.     </Border>
10. </UserControl>

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1. public partial class UserControl1 : UserControl
2. {
3.     public UserControl1()
4.     {
5.         InitializeComponent();
6.         this.UserControl_TextBlock.Initialized += UserControl_TextBlock_Initialized;
7.         this.UserControl_TextBlock.Loaded += UserControl_TextBlock_Loaded;
8.         this.UserControl_TextBlock.AttachedToVisualTree += UserControl_TextBlock_AttachedToVisualTree;
9.         this.UserControl_TextBlock.AttachedToLogicalTree += UserControl_TextBlock_AttachedToLogicalTree;
10.         this.UserControl_TextBlock.DetachedFromVisualTree += UserControl_TextBlock_DetachedFromVisualTree;
11.         this.UserControl_TextBlock.DetachedFromLogicalTree += UserControl_TextBlock_DetachedFromLogicalTree;
12.     }
14.     private void UserControl_TextBlock_DetachedFromLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
15.     {
16.         Debug.WriteLine("UserControl_TextBlock_DetachedFromLogicalTree");
17.     }
19.     private void UserControl_TextBlock_DetachedFromVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
20.     {
21.         Debug.WriteLine("UserControl_TextBlock_DetachedFromVisualTree");
22.     }
24.     private void UserControl_TextBlock_AttachedToLogicalTree(object? sender, Avalonia.LogicalTree.LogicalTreeAttachmentEventArgs e)
25.     {
26.         Debug.WriteLine("UserControl_TextBlock_AttachedToLogicalTree");
27.     }
29.     private void UserControl_TextBlock_AttachedToVisualTree(object? sender, VisualTreeAttachmentEventArgs e)
30.     {
31.         Debug.WriteLine("UserControl_TextBlock_AttachedToVisualTree");
32.     }
34.     private void UserControl_TextBlock_Loaded(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
35.     {
36.         Debug.WriteLine("UserControl_TextBlock_Loaded");
37.     }
39.     private void UserControl_TextBlock_Initialized(object? sender, System.EventArgs e)
40.     {
41.         Debug.WriteLine("UserControl_TextBlock_Initialized");
42.     }
43. }

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• 当我们点击MainWindow中的 按钮，弹出Window1 窗口时：
  

1. UserControl_TextBlock_AttachedToLogicalTree
2. InitializeComponent 初始化
3. Button1_AttachedToVisualTree
4. UserControl1_AttachedToVisualTree
5. UserControl_TextBlock_AttachedToVisualTree
6. UserControl_TextBlock_Initialized
7. Window1_Activated
8. Window1_Opened
9. UserControl1_Loaded
10. UserControl_TextBlock_Loaded
11. Window1_Loaded
12. Window1_Deactivated

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• 当我们点击Window1中的 关闭按钮时：
  

1. Window1_Activated
2. Window1_Closing
3. Window1_Deactivated
4. Window1_DetachedFromLogicalTree
5. Button1_DetachedFromLogicalTree
6. UserControl1_DetachedFromLogicalTree
7. UserControl_TextBlock_DetachedFromLogicalTree
8. Window1_DetachedFromVisualTree
9. Button1_DetachedFromVisualTree
10. UserControl1_DetachedFromVisualTree
11. UserControl_TextBlock_DetachedFromVisualTree
12. Window1_Closed

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3. 小结

通过以上案例可知：

• 当Window内全部的控件都完成了Loaded以后，Window 才会进行Loaded
  
• 控件在所在的Window 被Show出来时的生命周期：
  
  
  
  • 附加到逻辑树（AttachedToLogicalTree）
    
  • 附加到视觉树（AttachedToVisualTree）
    
  • 初始化完成（Initialized）
    
  • 加载完成（Loaded）
    
  
  
• 控件在所在的Window 被关闭时的生命周期：
  
  
  
  • 从逻辑树分离（DetachedFromLogicalTree）
    
  • 从视觉树分离（DetachedFromVisualTree）
    
  
  

   视觉树和逻辑树案例说明：
  

• Window1 中的StackPanel 下 有 Button 和 UserControl1
  
• UserControl1 中的Border 下 有 TextBlock
  
• 视觉树：到Window1 的Button 和 UserControl 为止
  
• 逻辑树：细化到UserControl的 TextBlock 为止
  

  

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结语

回到目录页： Avalonia 知识汇总
希望以上内容可以帮助到各人，如文中有不对之处，还请品评指正。

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参考资料：
Avalonia中的Window 生命周期
Avalonia的UI组件

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