设置自定义DependencyObjects的绑定 [英] Set bindings for custom DependencyObjects
问题描述
这是这里问题的延续:尝试设置一个自定义的DependencyObject.显然缺少一些东西.编辑原始问题不切实际.变化太大了.所以我开始一个新的问题.
This is a continuation of a question here: Trying to setup a custom DependencyObject. Clearly missing something. It's not practical to edit the original question; changes are too great. So I'm starting a fresh question.
我正在尝试在我的UWP应用中设置自定义DependencyObjects之间的绑定.相关代码如下.我看到了对ActualWidthPropertyChanged的调用,但是它们没有触发对WidthPropertyChanged的任何调用.我想念什么?
I'm trying to setup bindings between custom DependencyObjects in my UWP app. The relevant code is below. I am seeing calls to ActualWidthPropertyChanged, but they are not triggering any call to WidthPropertyChanged. What am I missing?
class WindowsElement: DependencyObject
{
public WindowsElement()
{
}
public double Width
{
get
{
return (double)GetValue(WidthProperty);
}
set
{
SetValue(WidthProperty, value);
}
}
private static void WidthPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
WindowsElement element = (WindowsElement)o;
double width = (double)e.NewValue;
CommonDebug.LogLine("WPC", element, o, width);
element.Width = width;
}
private static void ActualWidthPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
WindowsElement element = (WindowsElement)o;
double width = (double)e.NewValue;
CommonDebug.LogLine("AWPC", o, e, width, element.Width);
element.ActualWidth = width;
}
public static readonly DependencyProperty WidthProperty = DependencyProperty.Register(
"Width",
typeof(double),
typeof(WindowsElement),
new PropertyMetadata((double)0, WidthPropertyChanged));
public double ActualWidth {
get
{
return (double)GetValue(ActualWidthProperty);
}
set
{
SetValue(ActualWidthProperty, value);
}
}
public static readonly DependencyProperty ActualWidthProperty =
DependencyProperty.Register(
"ActualWidth",
typeof(double),
typeof(WindowsElement),
new PropertyMetadata((double)0, ActualWidthPropertyChanged));
public static void MessWithBindings()
{
WindowsElement we1 = new WindowsElement();
WindowsElement we2 = new WindowsElement();
var b = new Binding
{
Source = we2,
Path = new PropertyPath("ActualWidth")
};
BindingOperations.SetBinding(we1, WindowsElement.WidthProperty, b);
we2.ActualWidth = 13;
CommonDebug.LogLine(we1, we1.Width, we1.ActualWidth, we2, we2.Width, we2.ActualWidth);
}
}
推荐答案
我看到了对ActualWidthPropertyChanged的调用,但是它们没有触发对WidthPropertyChanged的任何调用.我想念什么?
I am seeing calls to ActualWidthPropertyChanged, but they are not triggering any call to WidthPropertyChanged. What am I missing?
要解决此问题,您需要在源对象上实现INotifyPropertyChanged接口,以便源可以报告更改.
To solve this question, you would need to implement the INotifyPropertyChanged interface on the source object so that the source can report changes.
请参见以下代码:
class WindowsElement : DependencyObject, INotifyPropertyChanged
{
public WindowsElement()
{
}
public double Width
{
get
{
return (double)GetValue(WidthProperty);
}
set
{
SetValue(WidthProperty, value);
}
}
private static void WidthPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
WindowsElement element = (WindowsElement)o;
double width = (double)e.NewValue;
CommonDebug.LogLine("WPC", element, o, width);
//element.Width = width;
element.RaisedPropertyChanged("Width");
}
private static void ActualWidthPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{
WindowsElement element = (WindowsElement)o;
double width = (double)e.NewValue;
CommonDebug.LogLine("AWPC", o, e, width, element.Width);
//element.ActualWidth = width;
element.RaisedPropertyChanged("ActualWidth");
}
public event PropertyChangedEventHandler PropertyChanged;
private void RaisedPropertyChanged(string PropertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));
}
public static readonly DependencyProperty WidthProperty = DependencyProperty.Register(
"Width",
typeof(double),
typeof(WindowsElement),
new PropertyMetadata((double)0, WidthPropertyChanged));
public double ActualWidth
{
get
{
return (double)GetValue(ActualWidthProperty);
}
set
{
SetValue(ActualWidthProperty, value);
}
}
public static readonly DependencyProperty ActualWidthProperty = DependencyProperty.Register(
"ActualWidth",
typeof(double),
typeof(WindowsElement),
new PropertyMetadata((double)0, ActualWidthPropertyChanged));
public static void MessWithBindings()
{
WindowsElement we1 = new WindowsElement();
WindowsElement we2 = new WindowsElement();
var b = new Binding
{
Source = we2,
Path = new PropertyPath("ActualWidth")
};
BindingOperations.SetBinding(we1, WindowsElement.WidthProperty, b);
we2.ActualWidth = 13;
CommonDebug.LogLine(we1, we1.Width, we1.ActualWidth, we2, we2.Width, we2.ActualWidth);
}
}
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