下面的例子演示了如何使用Color结构的Alpha成分，首先从Color结构中创建两个Color实例，一个是c1,它是蓝色的，其alpha值为100,另一个是绿色的alpha值为50.接着绘制三个实心图形
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g.FillRectangle(Brushes.White, this.ClientRectangle);
Color c1 = Color.FromArgb(100, Color.Blue);
Color c2 = Color.FromArgb(50, Color.Blue);
g.FillEllipse(Brushes.Red, 20, 20, 80, 80);
Point[] pa = new Point[] {
new Point(150,40),
new Point(90,40),
new Point(90,120)
};
g.FillPolygon(new SolidBrush(c2), pa);
}
}
