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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