改变多边形的点数

解决方案 窗口拖动的动态余量

所以我试图让我的多边形在窗口移动时移动。 我有;

private void ResetPolygon(Point Point1, Point Point2, Point Point3) { SpeechPoly.Points.Clear(); ObservableCollection myPointCollection = new ObservableCollection(); myPointCollection.Add(Point3); myPointCollection.Add(Point2); myPointCollection.Add(Point1); foreach (Point p in myPointCollection) { SpeechPoly.Points.Add(p); } } private void Window_LocationChanged(object sender, EventArgs e) { if (this.IsLoaded) { Point Point1 = new Point(newPoint3); Point Point2 = new Point(newPoint2); Point Point3 = new Point(newPoint1); ResetPolygon(newPoint1, newPoint2, newPoint3); //Write out the values of both the list and the polygon to screen! txtBlock.Text = newPoint1.X.ToString("N2") + ", " + newPoint1.Y.ToString("N2") + "\n" + newPoint2.X.ToString("N2") + ", " + newPoint2.Y.ToString("N2") + "\n" + newPoint3.X.ToString("N2") + ", " + newPoint3.Y.ToString("N2"); txtBlock.Text += "\n" + SpeechPoly.Points[0].X.ToString("N2") + ", " + SpeechPoly.Points[0].Y.ToString("N2") + "\n" + SpeechPoly.Points[1].X.ToString("N2") + ", " + SpeechPoly.Points[1].Y.ToString("N2") + "\n" + SpeechPoly.Points[2].X.ToString("N2") + ", "+ SpeechPoly.Points[2].Y.ToString("N2"); } } 

但是无论如何，Polygon都保持相同的形状，即使Textblock清楚地显示List中所有Points的值，而Polygon的点肯定会发生变化。

我还尝试将Polygon的Points属性绑定到我的代码。

 <Polygon Name="SpeechPoly" Points="{Binding myPointCollection, RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}" Stroke="Black" StrokeThickness="2"  

我也尝试使用pointsCollection而不是List但结果相同。 几乎看起来Polygon并不令人耳目一新。

Answer 1

我对之前给出的答案并不满意，因为它毕竟是一种解决方法。

我找到了一个更好的解决方案，不需要重置数据集。

因此，来自XAML的绑定被定向到具有INCC的属性，但是数据本身被转换为用于绘制时要使用的多边形的点。

 using System; using System.Collections.ObjectModel; using System.ComponentModel; using System.Windows; using System.Windows.Data; using System.Windows.Media; namespace WpfApplication9 { /// 
 /// Interaction logic for MainWindow.xaml /// 
 public partial class MainWindow : Window, INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; private ObservableCollection _myPointCollection = new ObservableCollection(); public ObservableCollection myPointCollection { get { return _myPointCollection; } } public MainWindow() { myPointCollection.Add(new Point(100, 50)); myPointCollection.Add(new Point(150, 100)); myPointCollection.Add(new Point(50, 100)); InitializeComponent(); DataContext = this; } private void ResetPolygon(Point Point1, Point Point2, Point Point3) { myPointCollection.Clear(); myPointCollection.Add(Point1); myPointCollection.Add(Point2); myPointCollection.Add(Point3); if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("myPointCollection")); } private void Window_LocationChanged(object sender, EventArgs e) { if (this.IsLoaded) { Random rnd = new Random(); Point Point1 = new Point(rnd.Next(50, 200), rnd.Next(50, 200)); Point Point2 = new Point(rnd.Next(50, 200), rnd.Next(50, 200)); Point Point3 = new Point(rnd.Next(50, 200), rnd.Next(50, 200)); ResetPolygon(Point1, Point2, Point3); } } } public class MyPointCollectionConverter : IValueConverter { #region IValueConverter Members public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { var regPtsColl = new PointCollection(); //regular points collection. var obsPtsColl = (ObservableCollection)value; //observable which is used to raise INCC event. foreach (var point in obsPtsColl) regPtsColl.Add(point); return regPtsColl; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { return null; } #endregion } } 

Answer 2

PointsCollection不使用INotifyCollectionChanged ..
所以约束永远不会知道某事已经改变了。

你可以通过刷新绑定来解决这个问题。

这是一个做你要求的例子：

 using System; using System.Windows; using System.Windows.Media; namespace WpfApplication9 { /// 
 /// Interaction logic for MainWindow.xaml /// 
 public partial class MainWindow : Window { public PointCollection myPointCollection { get; set; } public MainWindow() { myPointCollection = new PointCollection { new Point(100, 50), new Point(150, 100), new Point(50, 100) }; InitializeComponent(); DataContext = this; } private void ResetPolygon(Point Point1, Point Point2, Point Point3) { myPointCollection[0] = Point1; myPointCollection[1] = Point2; myPointCollection[2] = Point3; DataContext = null; DataContext = this; } private void Window_LocationChanged(object sender, EventArgs e) { if (this.IsLoaded) { Random rnd = new Random(); Point Point1 = new Point(rnd.Next(50, 200), rnd.Next(50, 200)); Point Point2 = new Point(rnd.Next(50, 200), rnd.Next(50, 200)); Point Point3 = new Point(rnd.Next(50, 200), rnd.Next(50, 200)); ResetPolygon(Point1, Point2, Point3); } } } } 

Answer 3

那么你在Window_LocationChanged处理程序中做的是添加点，所以难怪你最终得到更多的多边形。 您的myPointCollection必须是ObservableCollection ，您必须在添加点之前清除该集合。 我还想知道你是否可以使用从Pointinheritance的类（ System.Windows.Point ），但是将x和y重载到NotifyingPropertyChanged它们，以便绑定可以更新。 如果可行，则不必再更改Collection，而是更改Collection内容。

更新后编辑：

看起来问题出现在您的更新中：因为您使用相同的Collection更新它，所以不会发生更新。
这是完全正常的行为，因为Collection（一个PointCollection ）没有实现CollectionChanged ，所以即使你清除它，clr’看到’的所有东西都是同一个对象，所以没有变化，因此没有更新。

您不应修改（清除）Xaml Polygon对象本身的点集合，因为绑定就足够了。

1. 尝试每次创建一个新的PointCollection ，添加点，并将列表分配给多边形点。

2. 或尝试制作通知点并更改积分。 也许你可以用空字符串“”通知X和Y，这意味着一切都改变了，或者用“X”通知X，用“Y”通知Y.