派生自 Shape 的 WPF 自定义 Shape 类

Question

我正在尝试在 WPF 中创建一个自定义楔形类，派生自抽象 Shape 类，并且能够像任何其他形状一样在 XAML 中定义它。

我一直在 Google 上搜索有关如何执行此操作的完整教程，但我发现的只是自定义控件的内容。我想要的是创建一个楔形类，它允许我指定内半径、外半径、这个楔形将是 360 度中的多少个部分（即，如果我想在圆周围安装 24 个这些楔形，这个楔形将是这 24 个空间之一的正确大小），以及它的位置（它将占据这 24 个空间之一）。这些都是依赖属性，我已经注册了。

DefiningGeometry 属性调用一个方法，该方法执行计算点和绘制形状的所有逻辑。

我遇到的问题是 VS2010 使用属性“模板”的设置器自动创建了一个样式。然后，当我编译时，它给了我一个错误提示：

“错误 3 在类型 'WpfApplication1.Wedge' 上找不到样式属性 'Template'。第 8 行位置 17。C:\Users\rflint\Desktop\WpfApplication1\WpfApplication1\Themes\Generic.xaml 8 17 WpfApplication1”

如果我将此注释掉，则所有内容都会编译，但楔形不会显示在表单上。如何实现此模板设置器属性？我需要吗？

XAML：

    <my:Wedge CenterPoint="300,300" InnerRadius="100" OuterRadius="200" Sections="12" Position="0" Stroke="Transparent" Fill="#FFCC7329" />

C#：

protected override Geometry DefiningGeometry
{
  get
  {
    using (StreamGeometryContext context = geometry.Open())
    {
      DrawWedgeGeometry(context);
    }

    return geometry;
  }
}

        private void DrawWedgeGeometry(StreamGeometryContext context)
    {
        double wedgeAngle = 360/Sections;
        double angleA = (Position * wedgeAngle) + (wedgeAngle/2);
        double angleB = (Position * wedgeAngle) - (wedgeAngle/2);
        Point point1 = getPointOnCircle(CenterPoint, InnerRadius, angleA);
        Point point2 = getPointOnCircle(CenterPoint, InnerRadius, angleB);
        Point point3 = getPointOnCircle(CenterPoint, OuterRadius, angleB);
        Point point4 = getPointOnCircle(CenterPoint, OuterRadius, angleA);

        Size innerSize = new Size(InnerRadius, InnerRadius);
        Size outerSize = new Size(OuterRadius, OuterRadius);

        context.BeginFigure(point1, true, true);
        context.ArcTo(point2, innerSize, 90, false, SweepDirection.Clockwise, true, true);
        context.LineTo(point3, true, true);
        context.ArcTo(point4, outerSize, 90, false, SweepDirection.Counterclockwise, true, true);
    }

Answer 1

我刚刚在 VS2012 上尝试过，效果很好，至少使用简单的椭圆几何：

public sealed class Wedge : Shape
{
    public Double Radius
    {
        get { return (Double)this.GetValue(RadiusProperty); }
        set { this.SetValue(RadiusProperty, value); }
    }
    public static readonly DependencyProperty RadiusProperty = DependencyProperty.Register(
      "Radius", typeof(Double), typeof(Wedge), new PropertyMetadata(0.0));

    protected override Geometry DefiningGeometry
    {
        get {return new EllipseGeometry(new Point(0, 0), this.Radius, this.Radius); }
    }
}

还有 XAML：

<local:Wedge Radius="50" Stroke="Black" Fill="Yellow" StrokeThickness="2" Canvas.Top="100" Canvas.Left="100" />

Answer 2

让我为您的问题提供一个简单的解决方案：

public class Wedge : Shape
{
    public Double StartAngle
    {
        get { return (Double)GetValue(StartAngleProperty); }
        set { SetValue(StartAngleProperty, value); }
    }

    public static readonly DependencyProperty StartAngleProperty =
        DependencyProperty.Register("StartAngle", typeof(Double), typeof(Wedge), new PropertyMetadata(0d));


    public Double EndAngle
    {
        get { return (Double)GetValue(EndAngleProperty); }
        set { SetValue(EndAngleProperty, value); }
    }

    public static readonly DependencyProperty EndAngleProperty =
        DependencyProperty.Register("EndAngle", typeof(Double), typeof(Wedge), new PropertyMetadata(0d));


    public Point Center
    {
        get { return (Point)GetValue(CenterProperty); }
        set { SetValue(CenterProperty, value); }
    }

    public static readonly DependencyProperty CenterProperty =
        DependencyProperty.Register("Center", typeof(Point), typeof(Wedge), new PropertyMetadata(new Point()));



    public Double InnerRadius
    {
        get { return (Double)GetValue(InnerRadiusProperty); }
        set { SetValue(InnerRadiusProperty, value); }
    }

    public static readonly DependencyProperty InnerRadiusProperty =
        DependencyProperty.Register("InnerRadius", typeof(Double), typeof(Wedge), new PropertyMetadata(0d));

    public Double OuterRadius
    {
        get { return (Double)GetValue(OuterRadiusProperty); }
        set { SetValue(OuterRadiusProperty, value); }
    }

    public static readonly DependencyProperty OuterRadiusProperty =
        DependencyProperty.Register("OuterRadius", typeof(Double), typeof(Wedge), new PropertyMetadata(0d));

    protected override Geometry DefiningGeometry
    {
        get
        {
            StreamGeometry geometry = new StreamGeometry();
            using (StreamGeometryContext context = geometry.Open())
            {
                Draw(context);
            }
            return geometry;
        }
    }

    private void Draw(StreamGeometryContext context)
    {
        var isStroked = Stroke != null & Stroke != Brushes.Transparent & StrokeThickness > 0;
        var isFilled = Fill != null & Fill != Brushes.Transparent;

        context.BeginFigure(
            GetPointOnCircle(Center, OuterRadius, StartAngle),
            isFilled, 
            true);

        context.ArcTo(
            GetPointOnCircle(Center, OuterRadius, EndAngle), 
            new Size(OuterRadius, OuterRadius),
            0,
            EndAngle - StartAngle > 180, 
            SweepDirection.Clockwise,
            isStroked, 
            true);

        context.LineTo(GetPointOnCircle(Center, InnerRadius, EndAngle), isStroked, true);

        context.ArcTo(
            GetPointOnCircle(Center, InnerRadius, StartAngle),
            new Size(InnerRadius, InnerRadius),
            0,
            EndAngle - StartAngle > 180,
            SweepDirection.Counterclockwise,
            isStroked,
            true);

        context.LineTo(GetPointOnCircle(Center, OuterRadius, StartAngle), isStroked, true);
    }

    private Point GetPointOnCircle(Point center, double radius, double angle)
    {
        var px = center.X + radius * Math.Cos(ToRadians(angle));
        var py = center.Y + radius * Math.Sin(ToRadians(angle));
        return new Point(px, py);
    }

    public double ToRadians(double angle)
    {
        return angle * Math.PI / 180;
    }
}