如何使用 WinForms (.NET) 绘制圆角矩形？

Question

使用 C# 绘制矩形，我需要在每个边缘绘制圆弧首先我绘制矩形，然后我需要单击按钮它会在边缘绘制圆弧，我该怎么做？

Answer 1

C# 中的图形类没有绘制圆角矩形的内置方法，但是有几种方法可以实现这种效果。 Jay Riggs 的答案中的链接提供了从哪里开始的好建议，另外我建议您查看这篇文章：

C# - Creating Rounded Rectangles Using A Graphics Path

首先，我们创建一个 GraphicsPath， 然后我们调用 StartFigure 以便 我们可以开始向路径添加边。 此代码的其余部分用于顶部 左角和顶线 圆角矩形。如果我们应该 为了使这个角变圆，我们添加了一个 弧 - 否则...

Answer 2

画一个圆角的矩形？

试试：

Extended Graphics - Rounded rectangles, Font metrics and more for C# 3.0
Extended Graphics - An implementation of Rounded Rectangle in C#

Answer 3

我知道这篇文章很旧，但在搜索如何在 C# 中制作圆角矩形时，它是热门文章，我遇到了一些问题。 AddArc 方法不准确，因此，如果您使用已接受答案中的代码，您将得到一个时髦的圆角矩形。左上角正确，右上和左下角畸形，右下角太小。我已经调整了代码中的一些内容以补偿 AddArc 的不准确性，并且我相信我有一个可行的解决方案来创建一个适当的圆角矩形。此版本还可以将矩形分成左上半部分和右下半部分，这对于进行 3d 效果的明暗阴影非常方便。

设置窗口区域并创建左上/右下路径以使用明暗笔进行着色的示例用法：

        Region = new Region(RoundedRectangles.RoundedRectangle.Create(new Rectangle(0, 0, Size.Width, Size.Height), 8, RoundedRectangles.RoundedRectangle.RectangleCorners.TopRight | RoundedRectangles.RoundedRectangle.RectangleCorners.TopLeft));
        TopLeftPath = RoundedRectangles.RoundedRectangle.Create(new Rectangle(0, 0, Size.Width, Size.Height), 8, RoundedRectangles.RoundedRectangle.RectangleCorners.TopRight | RoundedRectangles.RoundedRectangle.RectangleCorners.TopLeft, RoundedRectangles.RoundedRectangle.WhichHalf.TopLeft);
        BottomRightPath = RoundedRectangles.RoundedRectangle.Create(new Rectangle(0, 0, Size.Width-1, Size.Height-1), 8, RoundedRectangles.RoundedRectangle.RectangleCorners.TopRight | RoundedRectangles.RoundedRectangle.RectangleCorners.TopLeft, RoundedRectangles.RoundedRectangle.WhichHalf.BottomRight);

最后是代码：

using System;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace RoundedRectangles
{
public abstract class RoundedRectangle
{
    [Flags]
    public enum RectangleCorners
    {
        None = 0, TopLeft = 1, TopRight = 2, BottomLeft = 4, BottomRight = 8,
        All = TopLeft | TopRight | BottomLeft | BottomRight
    }

    public enum WhichHalf
    {
        TopLeft,
        BottomRight,
        Both
    }

    static void Corner(GraphicsPath path, int x1, int y1, int x2, int y2, int x3, int y3)
    {
        path.AddLine(x1, y1, x2, y2);
        path.AddLine(x2, y2, x3, y3);
    }

    public static GraphicsPath Create(int x, int y, int width, int height, int radius, RectangleCorners corners, WhichHalf half)
    {
        if (radius <= 0)
        {
            GraphicsPath rectp = new GraphicsPath();
            rectp.AddRectangle(new Rectangle(x, y, width, height));
            return rectp;
        }

        int dia = radius * 2;

        Rectangle TLarc = new Rectangle(x, y, dia, dia);
        Rectangle TRarc = new Rectangle(x + width - dia - 1, y, dia, dia);
        Rectangle BRarc = new Rectangle(x + width - dia - 1, y + height - dia - 1, dia, dia);
        Rectangle BLarc = new Rectangle(x, y + height - dia - 1, dia, dia);

        Rectangle TLsquare = new Rectangle(x, y, radius, radius);
        Rectangle TRsquare = new Rectangle(x + width - radius, y, radius, radius);
        Rectangle BRsquare = new Rectangle(x + width - radius, y + height - radius, radius, radius);
        Rectangle BLsquare = new Rectangle(x, y + height - radius, radius, radius);

        GraphicsPath p = new GraphicsPath();
        p.StartFigure();

        if (half == WhichHalf.Both || half == WhichHalf.TopLeft)
        {
            if (corners.HasFlag(RectangleCorners.BottomLeft))
                p.AddArc(BLarc, 135, 45);
            else
                p.AddLine(BLsquare.Left, BLsquare.Bottom, BLsquare.Left, BLsquare.Top);

            p.AddLine(BLsquare.Left, BLsquare.Top - 1, TLsquare.Left, TLsquare.Bottom + 1);

            if (corners.HasFlag(RectangleCorners.TopLeft))
                p.AddArc(TLarc, 180, 90);
            else
                Corner(p, TLsquare.Left, TLsquare.Bottom, TLsquare.Left, TLsquare.Top, TLsquare.Right, TLsquare.Top);

            p.AddLine(TLsquare.Right + 1, TLsquare.Top, TRsquare.Left - 1, TRsquare.Top);

            if (corners.HasFlag(RectangleCorners.TopRight))
                p.AddArc(TRarc, -90, 45);
        }

        if (half == WhichHalf.Both || half == WhichHalf.BottomRight)
        {
            if (corners.HasFlag(RectangleCorners.TopRight))
                p.AddArc(TRarc, -45, 45);
            else
                p.AddLine(TRsquare.Right, TRsquare.Top, TRsquare.Right, TRsquare.Bottom);

            p.AddLine(TRsquare.Right, TRsquare.Bottom + 1, BRsquare.Right, BRsquare.Top - 1);

            if (corners.HasFlag(RectangleCorners.BottomRight))
                p.AddArc(BRarc, 0, 90);
            else
                Corner(p, BRsquare.Right, BRsquare.Top, BRsquare.Right, BRsquare.Bottom, BRsquare.Left, BRsquare.Bottom);

            p.AddLine(BRsquare.Left - 1, BRsquare.Bottom, BLsquare.Right + 1, BLsquare.Bottom);

            if (corners.HasFlag(RectangleCorners.BottomLeft))
                p.AddArc(BLarc, 90, 45);
            else
                p.AddLine(BLsquare.Right, BLsquare.Bottom, BLsquare.Left, BLsquare.Bottom);
        }

        return p;
    }

    public static GraphicsPath Create(Rectangle rect, int radius, RectangleCorners c, WhichHalf which_half)
    { return Create(rect.X, rect.Y, rect.Width, rect.Height, radius, c, which_half); }

    public static GraphicsPath Create(Rectangle rect, int radius, RectangleCorners c)
    { return Create(rect.X, rect.Y, rect.Width, rect.Height, radius, c, WhichHalf.Both); }

    public static GraphicsPath Create(Rectangle rect, int radius)
    { return Create(rect.X, rect.Y, rect.Width, rect.Height, radius, RectangleCorners.All, WhichHalf.Both); }

}

}

Answer 4

以上所有内容都适用于绘图，但如果您想将图形路径转换为 ​​自定义控件 的区域，我认为您应该使用 CreateRoundRectRgn 函数（来自 gdi32）正确右上、左下和右下边缘的曲线（左上边缘已根据半径正确绘制）。快速浏览一下http://pages.citebite.com/e1u2t5b7t4bih（来自instanceofTom 的回答）

Answer 5

先画四条线，在四个角上画圆弧。

Answer 6

使用 Pen 的 LineJoin 属性

Pen myPen = new Pen(Brushes.Black);

myPen.Width = 8.0f;

// Set the LineJoin property
myPen.LineJoin = System.Drawing.Drawing2D.LineJoin.Round;

// Draw the rectangle
e.Graphics.DrawRectangle(myPen, new Rectangle(50, 50, 200, 200));