C#创建无毛刺圆角窗体

因为最近要为开发的软件制作一个启动窗体,由于四四方方的启动窗体感觉不太美观,便想着将启动窗体开发成圆角状,试着使用GDI+对Winform窗体进行重绘,虽然实现了圆角的功能但四个圆角会有毛刺状如图一所示,显得不是很美观。

图一

无意间看到一位博主的博客,查阅了相关的英文资料终于实现了无毛刺的圆角窗体,特整理如下:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace MyRoundedRectangle
{
    public partial class FormRoundedRectangle : Form
    {
        [Category("高级"), DefaultValue(true), Description("窗体是否固定大小,为true时,无法拖动边角调整窗体大小,默认true")]
        public bool FixedSize { get; set; } = true;

        public FormRoundedRectangle()
        {
            InitializeComponent();
        }

        private void FormRoundedRectangle_Load(object sender, EventArgs e)
        {
            this.FormBorderStyle = FormBorderStyle.None;
            Bitmap myBitmap = new Bitmap(this.Width, this.Height);
            Graphics graphics = Graphics.FromImage(myBitmap);
            Rectangle gradientRectangle = new Rectangle(0, 0, this.Width - 1, this.Height - 1);
            Brush b = new LinearGradientBrush(gradientRectangle, Color.SkyBlue, Color.SkyBlue, 0.0f);
            graphics.SmoothingMode = SmoothingMode.HighQuality;
            RoundedRectangle.FillRoundedRectangle(graphics, b, gradientRectangle, 40);
            SetBitmap(myBitmap);
        }

        public void SetBitmap(Bitmap bitmap)
        {
            SetBitmap(bitmap, 255);
        }

        public void SetBitmap(Bitmap bitmap, byte opacity)
        {
            if (bitmap.PixelFormat != PixelFormat.Format32bppArgb)
                throw new ApplicationException("The bitmap must be 32ppp with alpha-channel.");

            IntPtr screenDc = Win32.GetDC(IntPtr.Zero);
            IntPtr memDc = Win32.CreateCompatibleDC(screenDc);
            IntPtr hBitmap = IntPtr.Zero;
            IntPtr oldBitmap = IntPtr.Zero;

            try
            {
                hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
                oldBitmap = Win32.SelectObject(memDc, hBitmap);
                Win32.Size size = new Win32.Size(bitmap.Width, bitmap.Height);
                Win32.Point pointSource = new Win32.Point(0, 0);
                Win32.Point topPos = new Win32.Point(Left, Top);
                Win32.BLENDFUNCTION blend = new Win32.BLENDFUNCTION();
                blend.BlendOp = Win32.AC_SRC_OVER;
                blend.BlendFlags = 0;
                blend.SourceConstantAlpha = opacity;
                blend.AlphaFormat = Win32.AC_SRC_ALPHA;
                Win32.UpdateLayeredWindow(Handle, screenDc, ref topPos, ref size, memDc, ref pointSource, 0, ref blend, Win32.ULW_ALPHA);
            }
            finally
            {
                Win32.ReleaseDC(IntPtr.Zero, screenDc);
                if (hBitmap != IntPtr.Zero)
                {
                    Win32.SelectObject(memDc, oldBitmap);
                    Win32.DeleteObject(hBitmap);
                }
                Win32.DeleteDC(memDc);
            }
        }

        //通过重写 WndProc 实现拖拽调整窗体大小、拖拽移动窗体
        const int HTLEFT = 10;
        const int HTRIGHT = 11;
        const int HTTOP = 12;
        const int HTTOPLEFT = 13;
        const int HTTOPRIGHT = 14;
        const int HTBOTTOM = 15;
        const int HTBOTTOMLEFT = 0x10;
        const int HTBOTTOMRIGHT = 17;
        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if (m.Msg == 0x84)
            {
                if (!FixedSize)
                {
                    // 拖拽调整窗体大小
                    Point vPoint = new Point((int)m.LParam & 0xFFFF, (int)m.LParam >> 16 & 0xFFFF);
                    vPoint = PointToClient(vPoint);
                    if (vPoint.X <= 5)
                        if (vPoint.Y <= 5)
                            m.Result = (IntPtr)HTTOPLEFT;
                        else if (vPoint.Y >= ClientSize.Height - 5)
                            m.Result = (IntPtr)HTBOTTOMLEFT;
                        else m.Result = (IntPtr)HTLEFT;
                    else if (vPoint.X >= ClientSize.Width - 5)
                        if (vPoint.Y <= 5)
                            m.Result = (IntPtr)HTTOPRIGHT;
                        else if (vPoint.Y >= ClientSize.Height - 5)
                            m.Result = (IntPtr)HTBOTTOMRIGHT;
                        else m.Result = (IntPtr)HTRIGHT;
                    else if (vPoint.Y <= 5)
                        m.Result = (IntPtr)HTTOP;
                    else if (vPoint.Y >= ClientSize.Height - 5)
                        m.Result = (IntPtr)HTBOTTOM;
                }
                // 鼠标左键按下实现拖动窗口功能
                if (m.Result.ToInt32() == 1)
                {
                    m.Result = new IntPtr(2);
                }
            }
        }
    }
}
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MyRoundedRectangle
{
    /// <summary>
    /// 
    /// </summary>
    internal static class PerPixelAlphaBlend
    {
        public static void SetBitmap(Bitmap bitmap, int left, int top, IntPtr handle)
        {
            SetBitmap(bitmap, 255, left, top, handle);
        }

        public static void SetBitmap(Bitmap bitmap, byte opacity, int left, int top, IntPtr handle)
        {
            if (bitmap.PixelFormat != PixelFormat.Format32bppArgb)
                throw new ApplicationException("The bitmap must be 32ppp with alpha-channel.");

            IntPtr screenDc = Win32.GetDC(IntPtr.Zero);
            IntPtr memDc = Win32.CreateCompatibleDC(screenDc);
            IntPtr hBitmap = IntPtr.Zero;
            IntPtr oldBitmap = IntPtr.Zero;

            try
            {
                hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
                oldBitmap = Win32.SelectObject(memDc, hBitmap);

                Win32.Size size = new Win32.Size(bitmap.Width, bitmap.Height);
                Win32.Point pointSource = new Win32.Point(0, 0);
                Win32.Point topPos = new Win32.Point(left, top);
                Win32.BLENDFUNCTION blend = new Win32.BLENDFUNCTION();
                blend.BlendOp = Win32.AC_SRC_OVER;
                blend.BlendFlags = 0;
                blend.SourceConstantAlpha = opacity;
                blend.AlphaFormat = Win32.AC_SRC_ALPHA;

                Win32.UpdateLayeredWindow(handle, screenDc, ref topPos, ref size, memDc, ref pointSource, 0, ref blend, Win32.ULW_ALPHA);
            }
            finally
            {
                Win32.ReleaseDC(IntPtr.Zero, screenDc);
                if (hBitmap != IntPtr.Zero)
                {
                    Win32.SelectObject(memDc, oldBitmap);
                    Win32.DeleteObject(hBitmap);
                }
                Win32.DeleteDC(memDc);
            }
        }
    }
}
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MyRoundedRectangle
{
    /// <summary>
    /// 
    /// </summary>
    public static class RoundedRectangle
    {
        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;
        }

        public static void FillRoundedRectangle(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);
            }
        }
    }
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace MyRoundedRectangle
{
    /// <summary>
    /// 
    /// </summary>
    internal class Win32
    {
        public enum Bool
        {
            False = 0,
            True
        };

        [StructLayout(LayoutKind.Sequential)]
        public struct Point
        {
            public Int32 x;
            public Int32 y;

            public Point(Int32 x, Int32 y) { this.x = x; this.y = y; }
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct Size
        {
            public Int32 cx;
            public Int32 cy;

            public Size(Int32 cx, Int32 cy) { this.cx = cx; this.cy = cy; }
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        struct ARGB
        {
            public byte Blue;
            public byte Green;
            public byte Red;
            public byte Alpha;
        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]
        public struct BLENDFUNCTION
        {
            public byte BlendOp;
            public byte BlendFlags;
            public byte SourceConstantAlpha;
            public byte AlphaFormat;
        }

        public const Int32 ULW_COLORKEY = 0x00000001;
        public const Int32 ULW_ALPHA = 0x00000002;
        public const Int32 ULW_OPAQUE = 0x00000004;

        public const byte AC_SRC_OVER = 0x00;
        public const byte AC_SRC_ALPHA = 0x01;

        [DllImport("user32.dll", ExactSpelling = true, SetLastError = true)]
        public static extern Bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst, ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, Int32 crKey, ref BLENDFUNCTION pblend, Int32 dwFlags);

        [DllImport("user32.dll", ExactSpelling = true, SetLastError = true)]
        public static extern IntPtr GetDC(IntPtr hWnd);

        [DllImport("user32.dll", ExactSpelling = true)]
        public static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

        [DllImport("gdi32.dll", ExactSpelling = true, SetLastError = true)]
        public static extern IntPtr CreateCompatibleDC(IntPtr hDC);

        [DllImport("gdi32.dll", ExactSpelling = true, SetLastError = true)]
        public static extern Bool DeleteDC(IntPtr hdc);

        [DllImport("gdi32.dll", ExactSpelling = true)]
        public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);

        [DllImport("gdi32.dll", ExactSpelling = true, SetLastError = true)]
        public static extern Bool DeleteObject(IntPtr hObject);
    }
}

此代码是使用Layered Windows,使用一个分层窗口可以显著提高复杂形状、动画特效、透明通道混合效果等类型的窗体的性能和视觉效果。运行效果如下(图二):

图二

需要的同学可以进行参考并在自己需要的功能上进行修改。

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