如何在c#中绘制圆角矩形

我正在使用这段代码来制作一个圆角矩形。但它只绘制了矩形的左上角和右上角，更没有完成下部的矩形。如何让它完整、充实。我应该做出哪些改变？

public static Bitmap DrawRoundedRectangle(Bitmap Image, Color BoxColor, int XPosition, int YPosition,
        int Height, int Width, int CornerRadius)
    {
     Bitmap NewBitmap = new Bitmap(Image, Image.Width, Image.Height);
     using (Graphics NewGraphics = Graphics.FromImage(NewBitmap))
    {
        using (Pen BoxPen = new Pen(BoxColor))
        {
            using (GraphicsPath Path = new GraphicsPath())
            {
                   Path.AddLine(XPosition + CornerRadius, YPosition, XPosition + Width - (CornerRadius * 2), YPosition);
                    Path.AddArc(XPosition + Width - (CornerRadius * 2), YPosition, CornerRadius * 2, CornerRadius * 2, 270, 90);
                  Path.AddLine(XPosition + Width, YPosition + CornerRadius, XPosition + Width, YPosition + Height - (CornerRadius * 2));
                    Path.AddArc(XPosition + Width - (CornerRadius * 2), YPosition + Height - (CornerRadius * 2), CornerRadius * 2, CornerRadius * 2, 0, 90);
                 Path.AddLine(XPosition + Width - (CornerRadius * 2), YPosition + Height, XPosition + CornerRadius, YPosition + Height);
                   Path.AddArc(XPosition, YPosition + Height - (CornerRadius * 2), CornerRadius * 2, CornerRadius * 2, 90, 90);
                   Path.AddLine(XPosition, YPosition + Height - (CornerRadius * 2), XPosition, YPosition + CornerRadius);
                    Path.AddArc(XPosition, YPosition, CornerRadius * 2, CornerRadius * 2, 180, 90);
                     Path.CloseFigure();
                     NewGraphics.DrawPath(BoxPen, Path);
                 }
              }
          }
         return NewBitmap;
     }

public static GraphicsPath RoundedRect(Rectangle bounds, int radius)
{
    int diameter = radius * 2;
    Size size = new Size(diameter, diameter);
    Rectangle arc = new Rectangle(bounds.Location, size);
    GraphicsPath path = new GraphicsPath();

    if (radius == 0)
    {
        path.AddRectangle(bounds);
        return path;
    }

    // top left arc  
    path.AddArc(arc, 180, 90);

    // top right arc  
    arc.X = bounds.Right - diameter;
    path.AddArc(arc, 270, 90);

    // bottom right arc  
    arc.Y = bounds.Bottom - diameter;
    path.AddArc(arc, 0, 90);

    // bottom left arc 
    arc.X = bounds.Left;
    path.AddArc(arc, 90, 90);

    path.CloseFigure();
    return path;
}

您可以为以下两个扩展方法Graphics键入，以便您可以像平常一样使用它们Draw... and Fill...形状绘制方法。

public static void DrawRoundedRectangle(this Graphics graphics, Pen pen, Rectangle bounds, int cornerRadius)
{
    if (graphics == null)
        throw new ArgumentNullException(nameof(graphics));
    if (pen == null)
        throw new ArgumentNullException(nameof(pen));

    using (GraphicsPath path = RoundedRect(bounds, cornerRadius))
    {
        graphics.DrawPath(pen, path);
    }
}

public static void FillRoundedRectangle(this Graphics graphics, Brush brush, Rectangle bounds, int cornerRadius)
{
    if (graphics == null)
        throw new ArgumentNullException(nameof(graphics));
    if (brush == null)
        throw new ArgumentNullException(nameof(brush));

    using(GraphicsPath path = RoundedRect(bounds, cornerRadius))
    {
        graphics.FillPath(brush, path);
    }
}

2020年更新:

最近我做了我的绘图库 https://github.com/koszeggy/KGySoft.Drawing公开可用（NuGet https://www.nuget.org/packages/KGySoft.Drawing/）。随意探索图形扩展 https://github.com/koszeggy/KGySoft.Drawing/blob/master/Specific/GdiPlus/KGySoft.Drawing/Drawing/_Extensions/GraphicsExtensions.cs用于更多重载的类（每个角的自定义角半径）以及其他好东西。