protected override void OnPaintBackground(PaintEventArgs e)
2  {
3   LinearGradientBrush b = new LinearGradientBrush(this.ClientRectangle,
4    Color.Blue,Color.AliceBlue,90f); //线性渐变
5   e.Graphics.FillRectangle(b,this.ClientRectangle); // 填充窗体
6   b.Dispose(); // 释放资源
7  }
8

 //panel填充渐变背景色

private void panel1_Paint(object sender, PaintEventArgs e)
{
    LinearGradientBrush brush = new LinearGradientBrush(e.ClipRectangle, Color.Red, Color.Blue, LinearGradientMode.Horizontal);
    e.Graphics.FillRectangle(brush, e.ClipRectangle);
}