winform绘制圆形控件抗锯齿

效果

步骤

1.vs2019新建窗体项目

2.右键单击项目名称，选择添加->用户控件

3.命名为CircleControl，选择添加

4.右键单击我们的自定义控件，选择查看代码

5.添加以下属性

        /// 
        /// 中心颜色
        /// 
        private Color centerColor = Color.White;
        /// 
        /// 中心颜色
        /// 
        public Color CenterColor
        {
            set
            {
                centerColor = value;
            }
            get
            {
                return centerColor;
            }
        }
 
        /// 
        /// 边缘颜色
        /// 
        private Color edgeColor = Color.Yellow;
        /// 
        /// 边缘颜色
        /// 
        public Color EdgeColor
        {
            get
            {
                return edgeColor;
            }
            set
            {
                edgeColor = value;
            }
        }
 
        /// 
        /// 中心点
        /// 
        private PointF centerPoint = new PointF(3.5f, 3.5f);
 
        /// 
        /// 中心点横坐标
        /// 
        public float CenterX
        {
            set
            {
                centerPoint.X = value;
            }
            get
            {
                return centerPoint.X;
            }
        }
 
        /// 
        /// 中心点纵坐标
        /// 
        public float CenterY
        {
            set
            {
                centerPoint.Y = value;
            }
            get
            {
                return centerPoint.Y;
            }
        }

 6.重写OnLayout事件

        /// 
        /// 布局更改事件
        /// 
        /// 
        protected override void OnLayout(LayoutEventArgs e)
        {
            base.OnLayout(e);
 
            GraphicsPath path = new GraphicsPath();
            path.AddEllipse(new RectangleF(0f, 0f, ClientSize.Width * 1.0f, ClientSize.Height * 1.0f));
            PathGradientBrush brush = new PathGradientBrush(path);
            brush.CenterColor = centerColor;
            brush.SurroundColors = new Color[] { edgeColor };
            brush.WrapMode = WrapMode.TileFlipXY;
            brush.CenterPoint = centerPoint;
 
            Bitmap bitmap = new Bitmap(ClientSize.Width, ClientSize.Height);
            Graphics g = Graphics.FromImage(bitmap);
            g.SmoothingMode = SmoothingMode.AntiAlias;
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.FillPath(brush, path);
            g.DrawArc(new Pen(BackColor, 4), new RectangleF(0, 0, ClientSize.Width, ClientSize.Height), 0, 360);
            BackgroundImage = bitmap;
        }

7.构造方法中开启双缓冲

        /// 
        /// 构造函数
        /// 
        public CircleControl()
        {
            DoubleBuffered = true;
            InitializeComponent();
        }

8.重新生成解决方案

9.回到Form1窗体，在工具箱里可以看到我们的自定义控件已经加载完毕，将其拖到Form1窗体中，并按自己风格修改圆形尺寸和中心点位置，渐变颜色等，即可运行。

技术要点

避免闪屏【开启双缓冲】

DoubleBuffered = true;

避免PathGradientBrush的锯齿效果，在其外围画一个环【环的厚度刚好把锯齿填完就好】，圈的锯齿效果可以通过修改Graphics对象三个属性解决

Graphics g = Graphics.FromImage(bitmap);
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;

中心点大约在宽高的35%~40%之间看起来效果比较自然【个人认为】 

源文件代码

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圆形控件: C# winform实现圆形控件