C# 开发圆角控件(窗体)

最近在做卡片视图的程序，要求将控件做成带有圆角的效果，下面是我在网上查找的资料，经过测试，确定可以实现功能。其中方法三既适应于控件，也适应于窗体。

先上传效果图：

方法一：

增加命名空间:using System.Drawing.Drawing2D;  
添加方法如下:当然各角的点可根据需要确定. 

private void Type(Control sender, int p_1, double p_2)
        {
            GraphicsPath oPath = new GraphicsPath();
            oPath.AddClosedCurve(
                new Point[] {
            new Point(0, sender.Height / p_1),
            new Point(sender.Width / p_1, 0), 
            new Point(sender.Width - sender.Width / p_1, 0), 
            new Point(sender.Width, sender.Height / p_1),
            new Point(sender.Width, sender.Height - sender.Height / p_1), 
            new Point(sender.Width - sender.Width / p_1, sender.Height), 
            new Point(sender.Width / p_1, sender.Height),
            new Point(0, sender.Height - sender.Height / p_1) },

                (float)p_2);

            sender.Region = new Region(oPath);
        }

在窗体的paint和resize事件中增加:Type(this,20,0.1);  
参数20和0.1也可以根据自己的需要调整到最佳效

方法二：

public void SetWindowRegion()
        {

            System.Drawing.Drawing2D.GraphicsPath FormPath;

            FormPath = new System.Drawing.Drawing2D.GraphicsPath();

            Rectangle rect = new Rectangle(0, 22, this.Width, this.Height - 22);//this.Left-10,this.Top-10,this.Width-10,this.Height-10);                 

            FormPath = GetRoundedRectPath(rect, 30);

            this.Region = new Region(FormPath);

        }

        private GraphicsPath GetRoundedRectPath(Rectangle rect, int radius)
        {

            int diameter = radius;

            Rectangle arcRect = new Rectangle(rect.Location, new Size(diameter, diameter));

            GraphicsPath path = new GraphicsPath();

            //   左上角   

            path.AddArc(arcRect, 180, 90);

            //   右上角   

            arcRect.X = rect.Right - diameter;

            path.AddArc(arcRect, 270, 90);

            //   右下角   

            arcRect.Y = rect.Bottom - diameter;

            path.AddArc(arcRect, 0, 90);

            //   左下角   

            arcRect.X = rect.Left;

            path.AddArc(arcRect, 90, 90);

            path.CloseFigure();

            return path;

        }

在窗体的resize事件中增加:SetWindowRegion();  

方法三：通过Window系统API行数，修改控件和窗体为椭圆形状。代码如下所示：

[System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern IntPtr BeginPath(IntPtr hdc);
        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern int SetBkMode(IntPtr hdc, int nBkMode);
        const int TRANSPARENT = 1;
        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern IntPtr EndPath(IntPtr hdc);
        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern IntPtr PathToRegion(IntPtr hdc);
        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern int Ellipse(IntPtr hdc, int x1, int y1, int x2, int y2);
        [System.Runtime.InteropServices.DllImport("user32")]
        private static extern IntPtr SetWindowRgn(IntPtr hwnd, IntPtr hRgn, bool bRedraw);
        [System.Runtime.InteropServices.DllImport("user32")]
        private static extern IntPtr GetDC(IntPtr hwnd);

protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            IntPtr dc;
            IntPtr region;

            dc = GetDC(this.Handle);
            BeginPath(dc);
            SetBkMode(dc, TRANSPARENT);
            Ellipse(dc, 0, 0, this.Width - 3, this.Height - 2);
            EndPath(dc);
            region = PathToRegion(dc);
            SetWindowRgn(this.Handle, region, false);
        }