如何在c#中画一个圆角矩形

Question

我正在使用此代码制作圆角矩形。但它只绘制矩形的左上角和右上角，更没有完成下部的矩形。如何使它完整和充满。我应该做哪些改变？

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;
     }

Answer 1

    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Graphics 类型创建两种扩展方法，以便将它们用作通常的Draw... 和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("graphics");
        if (pen == null)
            throw new ArgumentNullException("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("graphics");
        if (brush == null)
            throw new ArgumentNullException("brush");

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

---

2020 年更新：

最近我公开了我的drawing libraries (NuGet)。随意探索 GraphicsExtensions 类以获得更多重载（每个角的自定义角半径）和其他好东西。

Answer 2

我已经为那些想要不同角落的人修改了 György Kőszeg 的答案。

public static GraphicsPath RoundedRect(Rectangle bounds, int radius1, int radius2, int radius3, int radius4)
    {
        int diameter1 = radius1 * 2;
        int diameter2 = radius2 * 2;
        int diameter3 = radius3 * 2;
        int diameter4 = radius4 * 2;

        Rectangle arc1 = new Rectangle(bounds.Location, new Size(diameter1, diameter1));
        Rectangle arc2 = new Rectangle(bounds.Location, new Size(diameter2, diameter2));
        Rectangle arc3 = new Rectangle(bounds.Location, new Size(diameter3, diameter3));
        Rectangle arc4 = new Rectangle(bounds.Location, new Size(diameter4, diameter4));
        GraphicsPath path = new GraphicsPath();

        // top left arc  
        if (radius1 == 0)
        {
            path.AddLine(arc1.Location, arc1.Location);
        }
        else
        {
            path.AddArc(arc1, 180, 90);
        }

        // top right arc  
        arc2.X = bounds.Right - diameter2;
        if (radius2 == 0)
        {
            path.AddLine(arc2.Location, arc2.Location);
        }
        else
        {
            path.AddArc(arc2, 270, 90);
        }

        // bottom right arc  

        arc3.X = bounds.Right - diameter3;
        arc3.Y = bounds.Bottom - diameter3;
        if (radius3 == 0)
        {
            path.AddLine(arc3.Location, arc3.Location);
        }
        else
        {
            path.AddArc(arc3, 0, 90);
        }

        // bottom left arc 
        arc4.X = bounds.Right - diameter4;
        arc4.Y = bounds.Bottom - diameter4;
        arc4.X = bounds.Left;
        if (radius4 == 0)
        {
            path.AddLine(arc4.Location, arc4.Location);
        }
        else
        {
            path.AddArc(arc4, 90, 90);
        }

        path.CloseFigure();
        return path;
    }