Я взял VB-код OP в качестве основы и с небольшой помощью MSDN по использованию PathGradientBrush придумал этот класс для C #.Зеленая и красная кнопки, как показано на рисунке ниже, используют мой код, две синие кнопки являются обычной версией.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;
namespace WindowsFormsApplication1
{
public class ColouredRadioButton : RadioButton
{
// Fields
private Color m_OnColour;
private Color m_OffColour;
private Rectangle m_glint;
private Rectangle m_circle;
private PathGradientBrush m_flareBrush;
private Pen m_outline;
// Properties
public Color OnColour
{
get
{
return m_OnColour;
}
set
{
if ((value == Color.White) || (value == Color.Transparent))
m_OnColour = Color.Empty;
else
m_OnColour = value;
}
}
public Color OffColour
{
get
{
return m_OffColour;
}
set
{
if ((value == Color.White) || (value == Color.Transparent))
m_OffColour = Color.Empty;
else
m_OffColour = value;
}
}
// Constructor
public ColouredRadioButton()
{
// Init
m_circle = new Rectangle(2, 5, 7, 7 /*Magic Numbers*/);
m_glint = new Rectangle(3, 6, 4, 4 /*Magic Numbers*/);
m_outline = new Pen(new SolidBrush(Color.Black), 1F /*Magic Numbers*/);
// Generate Glint
GraphicsPath Path = new GraphicsPath();
Path.AddEllipse(m_glint);
m_flareBrush = new PathGradientBrush(Path);
m_flareBrush.CenterColor = Color.White;
m_flareBrush.SurroundColors = new Color[] { Color.Transparent };
m_flareBrush.FocusScales = new PointF(0.5F, 0.5F/*Magic Numbers*/);
// Allows for Overlaying
SetStyle(ControlStyles.SupportsTransparentBackColor, true);
BackColor = Color.Transparent;
}
// Methods
protected override void OnPaint(PaintEventArgs e)
{
// Init
base.OnPaint(e);
Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.AntiAlias;
// Overlay Graphic
if (this.Checked)
{
if (OnColour != Color.Empty)
{
g.FillEllipse(new SolidBrush(OnColour), m_circle);
g.FillEllipse(m_flareBrush, m_glint);
g.DrawEllipse(m_outline, m_circle);
}
}
else
{
if (OffColour != Color.Empty)
{
g.FillEllipse(new SolidBrush(OffColour), m_circle);
g.FillEllipse(m_flareBrush, m_glint);
g.DrawEllipse(m_outline, m_circle);
}
}
}
}
}
Если вам интересно и вы хотитекод большого красного шара, который я использовал для проверки характеристик кисти, вот, пожалуйста ...
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
int Offset = 25;
int BoxSize = 100;
int GlintSize = (int)((double)BoxSize * ((double)3 / (double)4));
Rectangle Circle = new Rectangle(Offset, Offset, BoxSize, BoxSize);
Rectangle Glint = new Rectangle(Offset, Offset, GlintSize, GlintSize);
//Debug
//e.Graphics.FillRectangle(new SolidBrush(Color.Red), Circle);
//e.Graphics.FillRectangle(new SolidBrush(Color.BlueViolet), Glint);
//Generate Glint
GraphicsPath P = new GraphicsPath();
P.AddEllipse(Glint);
PathGradientBrush FlareBrush = new PathGradientBrush(P);
FlareBrush.CenterColor = Color.FromArgb(255, 255, 255, 255);
Color[] colors = { Color.Transparent };
FlareBrush.SurroundColors = colors;
e.Graphics.FillEllipse(new SolidBrush(Color.FromArgb(255, 255, 0, 0)), Circle);
e.Graphics.FillEllipse(FlareBrush, Glint);
e.Graphics.DrawEllipse(new Pen(new SolidBrush(Color.Black), 1F), Circle);
}
}
}