c# - 命名空间中不存在自定义控件？

Question

我一直对 C# 中的 WPF 绑定(bind)很感兴趣，并尝试将控件绑定(bind)到鼠标位置，但在得到令人沮丧的“命名空间”clr-命名空间中不存在名称“[control]”之后:[命名空间]"每次我将 xaml 代码粘贴到编辑器中时，我都认为不值得花时间研究这个问题。

现在我试图简单地实现一个 binded Arc drawing example from Stack Overflow并且再次遇到相同的错误。 (可在此处找到可运行的简短示例的所有代码)

因此，我梳理了针对此问题的所有 Stack Overflow 解决方案(它实际上似乎相当普遍)以及似乎零星 和无法解释 的解决方法和修复。

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1. This question说

If nothing else is possible, comment the lines which use the namespace, rebuild, and then build the full project again.

I also tried rebuilding the project, reopening Visual Studio. Nothing helped. I finally commented xaml, rebuilt the project, uncommented xaml and it finally worked! Strange issue.

1. This one据说将项目设置为 Release模式，另一个关于同一问题的回答者说要定义程序集:(xmlns:Local="clr-namespace:MusicPlayer.Controls;assembly=MusicPlayer") 其中也不适合我。
2. This person建议更改构建目标平台 (x86 - x64)

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我已经尝试了几乎所有这些解决方案，但都无济于事。 ReSharper 似乎知道 Arc 类存在于分配给 Local 的命名空间中，但 Visual Studio 不知道。

<Local:Arc Center="{Binding Path=PreviousMousePositionPixels}" 
         Stroke="White" 
         StrokeDashArray="4 4"
         SnapsToDevicePixels="True"
         StartAngle="0" 
         EndAngle="{Binding Path=DeltaAngle}" 
         SmallAngle="True"
         Radius="40"/>

---

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Shapes;

public sealed class Arc : Shape
{
    public Point Center
    {
        get { return (Point)GetValue(CenterProperty); }
        set { SetValue(CenterProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Center.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty CenterProperty =
        DependencyProperty.Register("Center", typeof(Point), typeof(Arc)
        , new FrameworkPropertyMetadata(new Point(0, 0), FrameworkPropertyMetadataOptions.AffectsRender));


    public double StartAngle
    {
        get { return (double)GetValue(StartAngleProperty); }
        set { SetValue(StartAngleProperty, value); }
    }

    // Using a DependencyProperty as the backing store for StartAngle.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty StartAngleProperty =
        DependencyProperty.Register("StartAngle", typeof(double), typeof(Arc)
        , new FrameworkPropertyMetadata(0.0, FrameworkPropertyMetadataOptions.AffectsRender));

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

    // Using a DependencyProperty as the backing store for EndAngle.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty EndAngleProperty =
        DependencyProperty.Register("EndAngle", typeof(double), typeof(Arc)
        , new FrameworkPropertyMetadata(Math.PI/2.0, FrameworkPropertyMetadataOptions.AffectsRender));

    public double Radius
    {
        get { return (double)GetValue(RadiusProperty); }
        set { SetValue(RadiusProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Radius.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty RadiusProperty =
        DependencyProperty.Register("Radius", typeof(double), typeof(Arc)
        , new FrameworkPropertyMetadata(10.0, FrameworkPropertyMetadataOptions.AffectsRender));



    public bool SmallAngle
    {
        get { return (bool)GetValue(SmallAngleProperty); }
        set { SetValue(SmallAngleProperty, value); }
    }

    // Using a DependencyProperty as the backing store for SmallAngle.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SmallAngleProperty =
        DependencyProperty.Register("SmallAngle", typeof(bool), typeof(Arc)
        , new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.AffectsRender));


    static Arc()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(Arc), new FrameworkPropertyMetadata(typeof(Arc)));
    }

    protected override Geometry DefiningGeometry
    {
        get
        {

            var a0 = StartAngle < 0 ? StartAngle + 2 * Math.PI : StartAngle;
            var a1 = EndAngle < 0 ? EndAngle + 2 * Math.PI : EndAngle;

            if (a1<a0)
            {
                a1 += Math.PI * 2;
            }

            SweepDirection d = SweepDirection.Counterclockwise;
            bool large;

            if (SmallAngle)
            {
                large = false;
                double t = a1;
                if ((a1-a0)>Math.PI)
                {
                    d = SweepDirection.Counterclockwise;
                }
                else
                {
                    d = SweepDirection.Clockwise;
                }


            }else{
                large = (Math.Abs(a1 - a0) < Math.PI);
            }

            Point p0 = Center + new Vector(Math.Cos(a0), Math.Sin(a0)) * Radius;
            Point p1 = Center + new Vector(Math.Cos(a1), Math.Sin(a1)) * Radius;


            List<PathSegment> segments = new List<PathSegment>(1);
            segments.Add(new ArcSegment(p1, new Size(Radius, Radius), 0.0, large, d, true));

            List<PathFigure> figures = new List<PathFigure>(1);
            PathFigure pf = new PathFigure(p0, segments, true);
            pf.IsClosed = false;
            figures.Add(pf);

            Geometry g = new PathGeometry(figures, FillRule.EvenOdd, null);
            return g;
        }
    }
}

Answer 1

按照 RobCroll 的建议在命名空间内定义 Arc。检查下面的代码，我已将其包含在 Arc_Learning 命名空间中，该命名空间在 XAML 中称为本地。

    <Window x:Class="Arc_Learning.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Arc_Learning"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <local:Arc
             Stroke="White" 
         StrokeDashArray="4 4"
         SnapsToDevicePixels="True"
         StartAngle="0" 
         EndAngle="{Binding Path=DeltaAngle}" 
         SmallAngle="True"
         Radius="40"/>
    </Grid>
</Window>

    using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Shapes;

namespace Arc_Learning
{
    public sealed class Arc : Shape
    {
        public Point Center
        {
            get { return (Point)GetValue(CenterProperty); }
            set { SetValue(CenterProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Center.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty CenterProperty =
            DependencyProperty.Register("Center", typeof(Point), typeof(Arc)
            , new FrameworkPropertyMetadata(new Point(0, 0), FrameworkPropertyMetadataOptions.AffectsRender));


        public double StartAngle
        {
            get { return (double)GetValue(StartAngleProperty); }
            set { SetValue(StartAngleProperty, value); }
        }

        // Using a DependencyProperty as the backing store for StartAngle.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty StartAngleProperty =
            DependencyProperty.Register("StartAngle", typeof(double), typeof(Arc)
            , new FrameworkPropertyMetadata(0.0, FrameworkPropertyMetadataOptions.AffectsRender));

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

        // Using a DependencyProperty as the backing store for EndAngle.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty EndAngleProperty =
            DependencyProperty.Register("EndAngle", typeof(double), typeof(Arc)
            , new FrameworkPropertyMetadata(Math.PI / 2.0, FrameworkPropertyMetadataOptions.AffectsRender));

        public double Radius
        {
            get { return (double)GetValue(RadiusProperty); }
            set { SetValue(RadiusProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Radius.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty RadiusProperty =
            DependencyProperty.Register("Radius", typeof(double), typeof(Arc)
            , new FrameworkPropertyMetadata(10.0, FrameworkPropertyMetadataOptions.AffectsRender));



        public bool SmallAngle
        {
            get { return (bool)GetValue(SmallAngleProperty); }
            set { SetValue(SmallAngleProperty, value); }
        }

        // Using a DependencyProperty as the backing store for SmallAngle.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SmallAngleProperty =
            DependencyProperty.Register("SmallAngle", typeof(bool), typeof(Arc)
            , new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.AffectsRender));


        static Arc()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(Arc), new FrameworkPropertyMetadata(typeof(Arc)));
        }

        protected override Geometry DefiningGeometry
        {
            get
            {

                var a0 = StartAngle < 0 ? StartAngle + 2 * Math.PI : StartAngle;
                var a1 = EndAngle < 0 ? EndAngle + 2 * Math.PI : EndAngle;

                if (a1 < a0)
                {
                    a1 += Math.PI * 2;
                }

                SweepDirection d = SweepDirection.Counterclockwise;
                bool large;

                if (SmallAngle)
                {
                    large = false;
                    double t = a1;
                    if ((a1 - a0) > Math.PI)
                    {
                        d = SweepDirection.Counterclockwise;
                    }
                    else
                    {
                        d = SweepDirection.Clockwise;
                    }


                }
                else {
                    large = (Math.Abs(a1 - a0) < Math.PI);
                }

                Point p0 = Center + new Vector(Math.Cos(a0), Math.Sin(a0)) * Radius;
                Point p1 = Center + new Vector(Math.Cos(a1), Math.Sin(a1)) * Radius;


                List<PathSegment> segments = new List<PathSegment>(1);
                segments.Add(new ArcSegment(p1, new Size(Radius, Radius), 0.0, large, d, true));

                List<PathFigure> figures = new List<PathFigure>(1);
                PathFigure pf = new PathFigure(p0, segments, true);
                pf.IsClosed = false;
                figures.Add(pf);

                Geometry g = new PathGeometry(figures, FillRule.EvenOdd, null);
                return g;
            }
        }
    }
}