HelixToolkit.WPF Additional DependencyProperty 不工作

Posted 2023-04-01

【中文标题】HelixToolkit.WPF Additional DependencyProperty 不工作

【英文标题】：HelixToolkit.WPF Additional DependencyProperty not working

【发布时间】：2021-04-03 04:54:21

【问题描述】：

我正在基于 ExampleBrwoser 中的 HelixToolkit (SurfacePlot) 中的示例应用程序之一创建应用程序。

SurfacePlotVisual3D 类具有三个依赖属性，我尝试通过复制/重命名现有的来添加另一个，但它不起作用。

XAML

<h:HelixViewport3D ZoomExtentsWhenLoaded="True" ShowCoordinateSystem="True">
    <local:SurfacePlotVisual3D CurrentX="Binding CurrentX" Points="Binding Data" ColorValues="Binding ColorValues" SurfaceBrush="Binding SurfaceBrush" />            
</h:HelixViewport3D>

“CurrentX”属性是我尝试添加的属性。

SurfacePlotVisual3D.cs

 public class SurfacePlotVisual3D : ModelVisual3D
    
        public static readonly DependencyProperty CurrentXProperty =
          DependencyProperty.Register("CurrentX", typeof(double), typeof(SurfacePlotVisual3D),
                                      new UIPropertyMetadata(ModelChanged));

        public static readonly DependencyProperty PointsProperty =
            DependencyProperty.Register("Points", typeof(Point3D[,]), typeof(SurfacePlotVisual3D),
                                        new UIPropertyMetadata(null, ModelChanged));

        public static readonly DependencyProperty ColorValuesProperty =
            DependencyProperty.Register("ColorValues", typeof(double[,]), typeof(SurfacePlotVisual3D),
                                        new UIPropertyMetadata(null, ModelChanged));

        public static readonly DependencyProperty SurfaceBrushProperty =
            DependencyProperty.Register("SurfaceBrush", typeof(Brush), typeof(SurfacePlotVisual3D),
                                        new UIPropertyMetadata(null, ModelChanged));
...
...
    public Brush SurfaceBrush
        
            get  return (Brush)GetValue(SurfaceBrushProperty); 
            set  SetValue(SurfaceBrushProperty, value); 
        
        public double CurrentX
        
            get  return (double)GetValue(CurrentXProperty); 
            set  SetValue(CurrentXProperty, value); 
        

        private static void ModelChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        
            ((SurfacePlotVisual3D)d).UpdateModel();
        

MainWindow.cs

 public partial class MainWindow : Window
    
        public MainWindow()
        
            this.InitializeComponent();
            this.DataContext = new MainViewModel();
        
     

MainViewModel.cs

  public class MainViewModel : INotifyPropertyChanged
    
       ...
       ...
        public Func<double, double, double> Function  get; set; 
        public Point3D[,] Data  get; set; 
        public double[,] ColorValues  get; set; 
   
        public double CurrentX  get; set; 
        public MainViewModel()
        
            CurrentX = 6;
            MinX = 0;
            MaxX = 3;
            MinY = -2;
            MaxY = 2;
            Rows = 100;
            Columns = 50;

            Function = (x, y) => Math.Pow(Math.E, (-1) * Math.Pow(y, 2)) * 3*Math.Sin(2*x) + 2;
            ColorCoding = ColorCoding.ByGradientX;
            UpdateModel();
        
...
...

我可以在 MainViewModel 中更改“Data”、“ColorValues”和“Function”，效果立即在图中可见，但 CurrentX 属性不会做任何事情。

【问题讨论】：

没有实例方法UpdateModel的代码。首先需要了解的是它在VM中更新CenterX属性后调用。如果不是 - 可能您需要在注册 CurrentXProperty 时指定默认值 UIPropertyMetadata(default(double), ModelChanged))。

【参考方案1】：

正如 Anton 的评论所暗示的那样，缺少默认值是问题所在。

        public static readonly DependencyProperty CurrentXProperty =
          DependencyProperty.Register("CurrentX", typeof(double), typeof(SurfacePlotVisual3D),
                                      new UIPropertyMetadata((double)0, ModelChanged));

这解决了问题。需要 (double)0 强制转换，因为没有它你会得到一个异常，因为“object”不是“double”（在我的例子中）。非常感谢安东，让我开心！