WPF 中的附加属性和事件接线
我有一个附加属性（例如，它将文本框内的文本大写）。显然，我必须订阅 TextBox 的 TextChanged 事件，以便每次文本更新时将其大写。
public class Capitalize
{
// this is for enabling/disabling capitalization
public static readonly DependencyProperty EnabledProperty;
private static void OnEnabledChanged(
DependencyObject d,
DependencyPropertyChangedEventArgs e)
{
var tb = d as TextBox;
if ((bool)e.NewValue)
{
tb.TextChanged += new TextChangedEventHandler(tb_TextChanged);
}
else
{
tb.TextChanged -= new TextChangedEventHandler(tb_TextChanged);
}
}
}
正如我们所看到的，我们将事件处理程序添加到 TextBox，这（如果我理解正确的话）创建了一个强引用。这是否也意味着由于该强引用，GC 无法收集 TextBox？如果是 - 我应该在什么时候取消事件连接以便可以收集 TextBox？
I have an attached property (e.g. its capitalizing the text inside a TextBox). Obvoiusly I must subscribe to the TextBox's TextChanged event to capitalize it every time text updates.
public class Capitalize
{
// this is for enabling/disabling capitalization
public static readonly DependencyProperty EnabledProperty;
private static void OnEnabledChanged(
DependencyObject d,
DependencyPropertyChangedEventArgs e)
{
var tb = d as TextBox;
if ((bool)e.NewValue)
{
tb.TextChanged += new TextChangedEventHandler(tb_TextChanged);
}
else
{
tb.TextChanged -= new TextChangedEventHandler(tb_TextChanged);
}
}
}
As we see we add event handlers to the TextBox which (if I understand correctly) creates a strong reference. Does this also mean that because of that strong ref the GC cannot collect the TextBox? If yes - at which point should I unwire the event so that the TextBox can be collected?
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引用则相反，即文本框保存对事件处理程序的引用。所以不存在内存泄漏的可能性。
The reference goes the other way around, i.e. the text box holds the reference to the event handler. So there is no possibility for memory leaks.