如果我将一个控件绑定到另一个控件，并且其中一个控件死亡，那么绑定会发生什么情况？

发布于 2024-12-01 09:36:17 字数 304 浏览 1 评论 0原文

例如，让我们采用编程绑定：

Binding binding = new Binding("MyProperty");
binding.Converter = new BooleanToVisibilityConverter();
binding.Source = myWindow.myObject

myButton.SetBinding(Button.VisibilityProperty, binding);

如果 myWindow 死亡并被垃圾收集，会发生什么...我是否也负责释放绑定，或者它自己知道如何执行此操作？

原文

for example, let's take a programmatic binding:

Binding binding = new Binding("MyProperty");
binding.Converter = new BooleanToVisibilityConverter();
binding.Source = myWindow.myObject

myButton.SetBinding(Button.VisibilityProperty, binding);

What happens if myWindow dies and gets garbage collected... am I responsible for freeing up the binding as well, or does it know how to do that itself?

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羁〃客ぐ 2024-12-08 09:36:17

对于绑定来说情况并非如此，即使您使用 Source 作为 Binding，也不会出现内存泄漏。

要验证这一点，

请在 Xaml 中创建一个 StackPanel、一个 TextBox (tb1) 和两个 Buttons
在后面的代码中创建一个新的 TextBox< /code> (tb2)
在 tb1 上设置一个 Binding，并将 Source 设置为 tb2
在 tb2 上创建一个 WeakReference（这不应该如果有泄漏，则进行 GC）
将 tb2 添加到 StackPanel
运行程序并验证绑定是否有效
单击“删除”
单击“是否还活着？”

它返回 false，源 TextBox (tb2) 已被垃圾收集，因此我们没有内存泄漏

编辑：您还可以移动第一个 TextBox< 的创建/code> 从 Xaml 到代码隐藏并使用两个 WeakReferences （每个 TextBox 一个）并验证两个 textBox 是否正确进行 GC，您将看到这是真的。

Xaml

<StackPanel Name="stackPanel">
    <TextBox Name="textBox"/>
    <Button Name="removeButton" Content="Remove" Click="removeButton_Click"/>
    <Button Name="isAliveButton" Content="Is Alive?" Click="isAliveButton_Click"/>
</StackPanel>

代码隐藏

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        TextBox toBeGCdTextBox = new TextBox();
        stackPanel.Children.Add(toBeGCdTextBox);
        Binding textBinding = new Binding
        {
            Path = new PropertyPath("Text"),
            Source = toBeGCdTextBox
        };
        textBox.SetBinding(TextBox.TextProperty, textBinding);
        _weak = new WeakReference(toBeGCdTextBox);
    }
    private WeakReference _weak;
    private void isAliveButton_Click(object sender, RoutedEventArgs e)
    {
        GC.Collect();
        MessageBox.Show(_weak.IsAlive.ToString());
    }

    private void removeButton_Click(object sender, RoutedEventArgs e)
    {
        Debug.Assert(_weak.Target == stackPanel.Children[3]);
        stackPanel.Children.Remove(stackPanel.Children[3]);
    }
}

This is not true for Bindings, you'll have no memory leak even if you use Source for the Binding.

To verify this

Create a StackPanel, a TextBox (tb1) and two Buttons in Xaml
In code behind you create a new TextBox (tb2)
Set a Binding on tb1 with Source set to tb2
Create a WeakReference on tb2 (which shouldn't be GC'd if we have a leak)
Add tb2 to the StackPanel
Run the program and verify that the binding works
Click Remove
Click Is Alive?

It returns false, the source TextBox (tb2) has been garbage collected so we have no memory leak

Edit: You can also move the creation of the first TextBox from Xaml to code behind and use two WeakReferences (one for each TextBox) and verify that both textBoxes get GC'd properly and you'll see that this is true.

Xaml

<StackPanel Name="stackPanel">
    <TextBox Name="textBox"/>
    <Button Name="removeButton" Content="Remove" Click="removeButton_Click"/>
    <Button Name="isAliveButton" Content="Is Alive?" Click="isAliveButton_Click"/>
</StackPanel>

Code Behind

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        TextBox toBeGCdTextBox = new TextBox();
        stackPanel.Children.Add(toBeGCdTextBox);
        Binding textBinding = new Binding
        {
            Path = new PropertyPath("Text"),
            Source = toBeGCdTextBox
        };
        textBox.SetBinding(TextBox.TextProperty, textBinding);
        _weak = new WeakReference(toBeGCdTextBox);
    }
    private WeakReference _weak;
    private void isAliveButton_Click(object sender, RoutedEventArgs e)
    {
        GC.Collect();
        MessageBox.Show(_weak.IsAlive.ToString());
    }

    private void removeButton_Click(object sender, RoutedEventArgs e)
    {
        Debug.Assert(_weak.Target == stackPanel.Children[3]);
        stackPanel.Children.Remove(stackPanel.Children[3]);
    }
}

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