我在 ClassA 中有一个 DependencyProperty。我从 ClassA 派生了另一个 ClassB。在 ClassA 中更新或更改此属性的值时,如何在派生的 ClassB 中通知或反映它而不在 ClassA 中添加任何其他代码?
问问题
2744 次
4 回答
6
通过派生类中的DependencyProperty.OverrideMetadata为 ClassB 注册 PropertyChangedCallback:
class ClassB
{
static ClassB()
{
ClassA.SomeValueProperty.OverrideMetadata(
typeof(ClassB), new PropertyMetadata(SomeValuePropertyChanged);
}
private static SomeValuePropertyChanged(
DependencyObject o, DependencyPropertyChangedArgs e)
{
...
}
}
于 2013-10-24T08:11:27.547 回答
5
如果您希望在两个类中引发属性更改,您可以添加另一个所有者。
using System.Windows;
namespace dp
{
public class ClassA : DependencyObject
{
public string TestProperty
{
get { return (string)GetValue(TestPropertyProperty); }
set { SetValue(TestPropertyProperty, value); }
}
public static readonly DependencyProperty TestPropertyProperty =
DependencyProperty.Register("TestProperty", typeof(string), typeof(ClassA), new PropertyMetadata(null, new PropertyChangedCallback( (s, e)=>
{
})));
}
public class ClassB : ClassA
{
static ClassB()
{
TestPropertyProperty.AddOwner(typeof(ClassB), new PropertyMetadata((s, e) =>
{
}));
}
}
public partial class MainWindow : Window
{
public ClassB TestClassB
{
get { return (ClassB)GetValue(TestClassBProperty); }
set { SetValue(TestClassBProperty, value); }
}
public static readonly DependencyProperty TestClassBProperty =
DependencyProperty.Register("TestClassB", typeof(ClassB), typeof(MainWindow), new PropertyMetadata(null));
public MainWindow()
{
InitializeComponent();
TestClassB = new ClassB();
TestClassB.TestProperty = "test";
}
}
}
于 2013-10-24T08:14:40.370 回答
0
只是评论:如果您使用 B 类的 2 个实例,则会出现错误
- _innerException {“PropertyMetadata 已经为类型 'ClassB' 注册。”} System.Exception {System.ArgumentException}
于 2020-01-16T09:01:59.540 回答
-1
public class ClassA : DependencyObject
{
/// <summary>
///
/// </summary>
public string PropertyA
{
get { return (string)GetValue(PropertyAProperty); }
set { SetValue(PropertyAProperty, value); }
}
/// <summary>
/// Identifies the <see cref="PropertyA"/> dependency property.
/// </summary>
public static readonly DependencyProperty PropertyAProperty =
DependencyProperty.Register("PropertyA", typeof(string), typeof(ClassA), new PropertyMetadata("A"));
}
public class ClassB : ClassA
{
/// <summary>
///
/// </summary>
public string PropertyB
{
get { return (string)GetValue(PropertyBProperty); }
set { SetValue(PropertyBProperty, value); }
}
/// <summary>
/// Identifies the <see cref="PropertyB"/> dependency property.
/// </summary>
public static readonly DependencyProperty PropertyBProperty =
DependencyProperty.Register("PropertyB", typeof(string), typeof(ClassA), new PropertyMetadata("B"));
public ClassB()
{
ClassA.PropertyAProperty.OverrideMetadata(typeof(ClassB), new PropertyMetadata(AValuePropertyChanged));
}
private static void AValuePropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
MessageBox.Show(e.NewValue.ToString());
}
}
public partial class MainWindow4 : Window
{
/// <summary>
///
/// </summary>
public MainWindow4()
{
InitializeComponent();
this.Reference = new ClassB();
}
private ClassB Reference { get; set; }
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Button_Click(object sender, RoutedEventArgs e)
{
this.Reference.PropertyA = "hello";
}
}
于 2013-10-24T08:22:24.580 回答