中引发时调用equation_PropertyChanged
我有一个自定义的UserControl子类从RichTextBox。该类有一个依赖属性Equation，它是双向绑定的。
当用户将一个项目放到控件上时，我改变了Equation。这将正确地将更改传播到绑定的另一端，从而触发属性更改通知，但UI没有更改。如果我将绑定更改为另一个对象，然后返回，它将显示更新后的Equation。
如何在不更改绑定的情况下强制刷新?现在我设置的是Equation=null，然后返回，这是可行的，但这看起来有点粗糙。一定有更优雅的。
这里是控件的相关部分。我想要发生的是OnEquationChanged回调在我改变方程(Equation. components . add (txt))后被调用。
public class EquationTextBox : RichTextBox
{
protected override void OnDrop(DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.StringFormat))
{
string str = (string)e.Data.GetData(DataFormats.StringFormat);
EquationText txt = new EquationText(str);
//// Preferred /////
Equation.Components.Add(txt);
//// HACK /////
Equation eqn = this.Equation;
eqn.Components.Add(txt);
this.Equation = null;
this.Equation = eqn;
///////////////
Console.WriteLine("Dropping " + str);
}
}
public Equation Equation
{
get { return (Equation)GetValue(EquationProperty); }
set { SetValue(EquationProperty, value); }
}
private static void onEquationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
string prop = e.Property.ToString();
EquationTextBox txtBox = d as EquationTextBox;
if(txtBox == null || txtBox.Equation == null)
return;
FlowDocument doc = txtBox.Document;
doc.Blocks.Clear();
doc.Blocks.Add(new Paragraph(new Run(txtBox.Equation.ToString())));
}
public static readonly DependencyProperty EquationProperty =
DependencyProperty.Register("Equation",
typeof(Equation),
typeof(EquationTextBox),
new FrameworkPropertyMetadata(null,
FrameworkPropertyMetadataOptions.AffectsRender,
new PropertyChangedCallback(onEquationChanged)));
private bool mIsTextChanged;
}
}
这是双向绑定另一端的属性。在上述代码中，equation_PropertyChanged事件作为equation_components . add (txt);
的结果被调用。public Equation Equation
{
get{ return mEquation; }
set { mEquation = value; NotifyPropertyChanged(); }
}
private void equation_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
NotifyPropertyChanged("Equation");
}
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
编辑 --------------------------
根据注释，我尝试像这样使用分派器(注意，这是我第一次尝试使用分派器)
string str = (string)e.Data.GetData(DataFormats.StringFormat);
EquationText txt = new EquationText(str);
Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(() =>
{
Equation.Components.Add(txt);
NotifyPropertyChanged("Equation");
}));
但仍然没有UI更新。
Edit 2 --------------------------
双向绑定在XAML
中完成<l:EquationTextBox x:Name="ui_txtVariableEquation" Grid.Row="0" Grid.Column="2"
Grid.RowSpan="3" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
AllowDrop="True"
Equation="{Binding SelectedVariableVM.Variable.Equation, Mode=TwoWay}">
</l:EquationTextBox>
与Components对象(在Equation类中)相关的信息
public class Equation : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public Equation()
{
mComponents = new ObservableCollection<EquationComponent>();
mComponents.CollectionChanged += new NotifyCollectionChangedEventHandler(components_CollectionChanged);
}
public Equation(string eqn) : this()
{
mComponents.Add(new EquationText(eqn));
}
public ObservableCollection<EquationComponent> Components
{
get{ return mComponents; }
set{ mComponents = value; NotifyPropertyChanged();}
}
public override string ToString()
{
string str = "";
for(int i=0; i<mComponents.Count; i++)
str += mComponents[i].ToString();
return str;
}
private void components_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
NotifyPropertyChanged("Components");
}
private ObservableCollection<EquationComponent> mComponents;
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Variable : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public Variable(string name = "var", VariableType type = VariableType.UnknownType) :
this(name, "", 0, type)
{
}
和
public class Variable : INotifyPropertyChanged
{
public Variable(string name, string unit, object val, VariableType type)
{
mEquation = new Equation(name + " = " + val.ToString() +
mEquation.PropertyChanged += new PropertyChangedEventHandler(equation_PropertyChanged);
}
...
public Equation Equation
{
get{ return mEquation; }
set { mEquation = value; NotifyPropertyChanged(); }
}
private void equation_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
NotifyPropertyChanged("Equation");
}
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
private Equation mEquation;
...
}
变量。当事件在Equation类
我认为问题是绑定产生的值实际上不是改变(它仍然是相同的Equation对象)。如果DP值没有更改，则不会调用DP更改处理程序。
也许，在您的DP更改处理程序中，您应该订阅新方程的PropertyChanged事件，然后在底层属性更改时重新构建文档:
private static void onEquationChanged(
DependencyObject d,
DependencyPropertyChangedEventArgs e)
{
var txtBox = d as EquationTextBox;
if (txtBox == null)
return;
var oldEquation = e.OldValue as Equation;
if (oldEquation != null)
oldEquation.PropertyChanged -= txtBox.OnEquationPropertyChanged;
var newEquation = e.NewValue as Equation;
if (newEquation != null)
newEquation.PropertyChanged += txtBox.OnEquationPropertyChanged;
txtBox.RebuildDocument();
}
private void OnEquationPropertyChanged(object sender, EventArgs e)
{
RebuildDocument();
}
private void RebuildDocument()
{
FlowDocument doc = this.Document;
doc.Blocks.Clear();
var equation = this.Equation;
if (equation != null)
doc.Blocks.Add(new Paragraph(new Run(equation.ToString())));
}