绘制开关按钮

[DefaultEvent("SwitchChanged")]
public class SwitchBox : Control {
    public SwitchBox() {
        this.SetStyle(ControlStyles.UserPaint, true);
        this.SetStyle(ControlStyles.ResizeRedraw, true);
        this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
        this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
        this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
        this.BackColor = Color.Transparent;
        this.ForeColor = Color.White;
        this.Cursor = Cursors.Hand;
    }
 
    private bool _IsNO;
 
    public bool IsNO {
        get { return _IsNO; }
        set {
            if (_IsNO == value) return;
            _IsNO = value;
            this.OnSwitchChanged(EventArgs.Empty);
            this.Invalidate();
        }
    }
 
    private string _OFFText = " OFF";
 
    public string OFFText {
        get { return _OFFText; }
        set {
            if (value == _OFFText) return;
            _OFFText = value;
            this.Invalidate();
        }
    }
 
    private string _NOText = " NO";
 
    public string NOText {
        get { return _NOText; }
        set {
            if (_NOText == value) return;
            _NOText = value;
            this.Invalidate();
        }
    }
 
    private Color _OFFColor = Color.Gray;
 
    public Color OFFColor {
        get { return _OFFColor; }
        set {
            if (_OFFColor == value) return;
            _OFFColor = value;
            this.Invalidate();
        }
    }
 
    private Color _NOColor = Color.DodgerBlue;
 
    public Color NOColor {
        get { return _NOColor; }
        set {
            if (_NOColor == value) return;
            _NOColor = value;
            this.Invalidate();
        }
    }
 
    protected override void OnClick(EventArgs e) {
        this._IsNO = !this._IsNO;
        this.Invalidate();
        this.OnSwitchChanged(EventArgs.Empty);
        base.OnClick(e);
    }
 
    public event EventHandler SwitchChanged;
 
    protected virtual void OnSwitchChanged(EventArgs e) {
        if (this.SwitchChanged != null) this.SwitchChanged(this, e);
    }
 
    protected override void OnMouseDown(MouseEventArgs e) {
        this.Focus();
        base.OnMouseDown(e);
    }
 
    protected override void OnPaint(PaintEventArgs e) {
        Graphics g = e.Graphics;
        g.SmoothingMode = SmoothingMode.HighQuality;
        StringFormat sf = new StringFormat();
        sf.Alignment = StringAlignment.Center;
        sf.LineAlignment = StringAlignment.Center;
        using (SolidBrush sb = new SolidBrush(this._IsNO ? this._NOColor : this._OFFColor)) {
            g.FillPath(
                sb,
                RenderHelper.CreateRoundedRectanglePath(new Rectangle(0, 2, this.Width - 1, this.Height - 5), 5)
                );
        }
        using (LinearGradientBrush lgb = new LinearGradientBrush(
            new Point(0, 2), new Point(0, this.Height - 3),
            Color.FromArgb(60, 0, 0, 0), Color.FromArgb(125, 255, 255, 255))) {
            g.DrawPath(
                new Pen(lgb),
                RenderHelper.CreateRoundedRectanglePath(new Rectangle(0, 3, this.Width - 1, this.Height - 6), 5)
                );
        }
        using (LinearGradientBrush lgb = new LinearGradientBrush(
           new Point(0, 2), new Point(0, this.Height - 3),
           Color.FromArgb(100, 0, 0, 0), Color.Transparent)) {
            g.DrawPath(
                new Pen(lgb),
                RenderHelper.CreateRoundedRectanglePath(new Rectangle(0, 2, this.Width - 1, this.Height - 6), 5)
                );
        }
 
        using (SolidBrush sb = new SolidBrush(this.ForeColor)) {
            g.DrawString(this._IsNO ? this._NOText : this._OFFText, this.Font, sb, new Rectangle(this._IsNO ? 1 : 26, 3, this.Width - 27, this.Height - 6), sf);
        }
        //==============
        int nLeft = this._IsNO ? this.Width - 26 : 0;
        using (LinearGradientBrush lgb = new LinearGradientBrush(
            new Point(0, 1), new Point(0, this.Height),
            Color.White, Color.FromArgb(60, 60, 60))) {
            g.DrawPath(
                new Pen(lgb),
                RenderHelper.CreateRoundedRectanglePath(new Rectangle(nLeft, 1, 25, this.Height - 2), 5)
                );
        }
        using (LinearGradientBrush lgb = new LinearGradientBrush(
            new Point(0, 1), new Point(0, this.Height),
            Color.FromArgb(255, 255, 255), Color.FromArgb(240, 240, 240))) {
            g.FillPath(
                lgb,
                RenderHelper.CreateRoundedRectanglePath(new Rectangle(nLeft, 1, 25, this.Height - 2), 5)
                );
        }
        using (LinearGradientBrush lgb = new LinearGradientBrush(
           new Point(0, 0), new Point(0, this.Height - 1),
           Color.FromArgb(200, 200, 200), Color.FromArgb(127, 127, 127))) {
 
            g.DrawPath(
                new Pen(lgb),
                RenderHelper.CreateRoundedRectanglePath(new Rectangle(nLeft, 0, 25, this.Height - 2), 5)
                );
        }
        base.OnPaint(e);
    }
}