绑定到可观察列表的折线<Point>不会刷新

Question

我有一个类(我们称之为externalClass)，里面有一个ObservableCollection<Point> channel1。(类本身不实现INotify)

在MainWindow中，我有一条多段线绑定到这个externalClass.channel1，它使用了从ObservableCollection到PointCollection的转换器。

因此，从C#绑定DataContext = externalClass;和XAML中，多段线看起来像：

<Polyline Points="{Binding channel1, Converter={StaticResource pointCollectionConverter}}" Stroke="#FF00E100" Name="line" />

我有一个类似的测试功能：

public void test()
{
ObservableCollection<Point> newone = new ObservableCollection<Point>();
for (int i = 0; i < debugCh1.Count; i++)
{
Point p1 = debugCh1[i];
p1.Y = p1.Y + 1;
newone.Add(p1);
}
channel1= newone;
}

如果我在转换器本身中添加一个断点，我可以看到在启动时会调用它(实际上会显示初始值(硬编码))。但当我将测试功能添加到按钮时。。它什么都不做(转换器不叫)

你知道在哪里停止变更通知吗？？？

解决方案

在阅读了答案并在谷歌上搜索了更多之后，我说出了灵魂。我想把它张贴在那里给其他人

所以。。所谓的externalClass必须继承自INotifyPropertyChanged，并且必须实现NotifyPropertyChanged所以所有的一切都必须这样声明：

public class externalClass  : INotifyPropertyChanged
{ 
....
// at some point you have your ObservableCollection<smth> as a property 
public ObservableCollection<Point> channel1 { get; set; }
....
//at some point you implement NotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string caller)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(caller));
}
}
....
//then whenever you need to fire the notification
[..]do something with channel1
NotifyPropertyChanged("channel1");

仅此而已。如果你加上一个合适的绑定(就像我在问题中展示的那样)，整个设置就会起作用。。至少我的工作了呵呵

祝你好运！感谢那些帮助我的人！！：D

Answer 1

多段线点在绑定时可能不会侦听INotifyCollectionChanged。尝试将Channel1作为属性公开，并使用"Channel1"提升INotifyPropertyChanged

Answer 2

首先，您需要创建自定义类PointCollection:

public class PointCollection : ObservableCollection<Point>
{
public PointCollection()
{
}

public PointCollection(IEnumerable<Point> points) : base(points)
{
}
}

其次，您需要创建自定义Polyline:

public class PolylineDynamic : Shape
{
private Geometry _polylineGeometry = Geometry.Empty;
public static readonly DependencyProperty PointsProperty = DependencyProperty.Register(nameof(Points), typeof(PointCollection), typeof(PolylineDynamic), new FrameworkPropertyMetadata(PointsChanged));
private static void PointsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((PolylineDynamic)d).PointsChanged(e);
}
private void PointsChanged(DependencyPropertyChangedEventArgs e)
{
if (e.OldValue is PointCollection oldPoints)
oldPoints.CollectionChanged -= OnPointsChanged;
if (e.NewValue is PointCollection newPoints)
newPoints.CollectionChanged += OnPointsChanged;
UpdatePolyline();
}
public PointCollection Points
{
get => (PointCollection)GetValue(PointsProperty);
set => SetValue(PointsProperty, value);
}
public static readonly DependencyProperty FillRuleProperty = DependencyProperty.Register(nameof(FillRule), typeof(FillRule), typeof(PolylineDynamic), new FrameworkPropertyMetadata(FillRule.EvenOdd));
public FillRule FillRule
{
get => (FillRule)GetValue(FillRuleProperty);
set => SetValue(FillRuleProperty, value);
}
protected override Geometry DefiningGeometry => _polylineGeometry;
private void OnPointsChanged(object sender, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
var aPoint = e.NewItems.OfType<Point>().Single();
Add(aPoint, e.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Remove:
Remove(e.OldStartingIndex);
break;
case NotifyCollectionChangedAction.Replace:
var rPoint = e.NewItems.OfType<Point>().Single();
Replace(rPoint, e.NewStartingIndex);
break;
}
}
protected void UpdatePolyline()
{
if (Points == null || Points.Count < 2)
_polylineGeometry = Geometry.Empty;
else
{
var pGeometry = GetPathGeometry();
for (var i = 0; i < Points.Count; i++)
{
if (i == 0)
continue;
var startPoint = Points[i - 1];
var point = Points[i];
var figure = new PathFigure { StartPoint = startPoint };
figure.Segments.Add(new LineSegment(point, true));
pGeometry.Figures.Add(figure);
}
}
}
private void Add(Point point, int index)
{
var pGeometry = GetPathGeometry();
if (pGeometry.Figures.Count == 0)
{
UpdatePolyline();
return;
}
if (index == Points.Count - 1)
{
var segment = new LineSegment(point, true);
var figure = new PathFigure { StartPoint = Points[index - 1] };
figure.Segments.Add(segment);
pGeometry.Figures.Add(figure);
}
else if (index == 0)
{
var segment = new LineSegment(Points[1], true);
var figure = new PathFigure { StartPoint = point };
figure.Segments.Add(segment);
pGeometry.Figures.Insert(0, figure);
}
else
{
var leftFigure = new PathFigure { StartPoint = Points[index - 1] };
leftFigure.Segments.Add(new LineSegment(point, true));
var rightFigure = new PathFigure { StartPoint = point };
rightFigure.Segments.Add(new LineSegment(Points[index + 1], true));
pGeometry.Figures.Insert(index - 1, leftFigure);
pGeometry.Figures.Insert(index, rightFigure);
}
InvalidateVisual();
}
private void Remove(int index)
{
var pGeometry = GetPathGeometry();
if (!pGeometry.Figures.Any())
{
_polylineGeometry = Geometry.Empty;
InvalidateVisual();
return;
}
if (index == Points.Count - 1 || index == 0)
pGeometry.Figures.RemoveAt(index);
else
{
var leftFigure = pGeometry.Figures[index - 1];
var rightFigure = pGeometry.Figures[index];
pGeometry.Figures.RemoveAt(index - 1);
rightFigure.StartPoint = ((LineSegment)leftFigure.Segments.Single()).Point;
}
InvalidateVisual();
}
private void Replace(Point point, int index)
{
var pGeometry = GetPathGeometry();
if (index == 0)
pGeometry.Figures[0].StartPoint = point;
else if (index == Points.Count - 1)
ReplaceSegment(pGeometry.Figures[index - 1], point);
else
{
ReplaceSegment(pGeometry.Figures[index - 1], point);
pGeometry.Figures[index].StartPoint = point;
}
InvalidateVisual();
}
private void ReplaceSegment(PathFigure figure, Point point)
{
figure.Segments.Clear();
figure.Segments.Add(new LineSegment(point, true));
}
private PathGeometry GetPathGeometry()
{
if (_polylineGeometry is PathGeometry pathGeometry)
return pathGeometry;
else
{
pathGeometry = new PathGeometry { FillRule = FillRule };
_polylineGeometry = pathGeometry;
return pathGeometry;
}
}
}

如果你需要更多的功能，你可以添加更多)