问题描述
我正在开发一个 avalonia wpf 应用程序,并且我注册了一个 AttachedProperty“IsFocused”,如下所示:
public class FocusExtension
{
public static readonly AttachedProperty<bool> IsFocusedProperty =
AvaloniaProperty.Registerattached<Control,bool>("IsFocused",typeof(FocusExtension));
public static bool GetIsFocused(Control element)
{
return element.GetValue(IsFocusedProperty);
}
public static void SetIsFocused(Control element,bool value)
{
element.SetValue(IsFocusedProperty,value);
OnIsFocusedPropertyChanged(element,value);
}
private static void OnIsFocusedPropertyChanged(
Control element,bool e)
{
if (e)
{
element.Focus();
}
}
}
并像这样在 xaml 中应用它:
<Button Content="Test" u:FocusExtension.IsFocused="{Binding SomeBoolPropertyInviewmodel}"/>
但是当“SomeBoolPropertyInviewmodel”从我的 viewmodel 设置为 true 时,它似乎不起作用,
解决方法
不能保证 SetIsFocused
会被调用,因为 element.SetValue(IsFocusedProperty,value)
可能会被直接调用。因此,您必须在静态构造函数中为属性更改事件添加一个处理程序:
static FocusExtension()
{
IsFocusedProperty.Changed.AddClassHandler<Control>(OnIsFocusedPropertyChanged);
}
private static void OnIsFocusedPropertyChanged(
Control element,AvaloniaPropertyChangedEventArgs e)
{
if ((bool)e.NewValue)
{
element.Focus();
}
}