GDI+ 图片颜色渐变

using System;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

using System.Drawing;

using System.Drawing.Imaging;

using System.Drawing.Drawing2D;

public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        Bitmap image = new Bitmap(300, 300);//定义位图实例，并初始化大小

        Graphics g = Graphics.FromImage(image);//定义绘图画面，封装上面的位图实例

        g.FillRectangle(Brushes.White, 0, 0, 300, 300); //定义矩形区域

        LinearGradientBrush myBrush;//创建一个渐变模式混合两种颜色的画刷

        int y = 20;

        foreach (LinearGradientMode gradientStyle in System.Enum.GetValues(typeof(LinearGradientMode)))

        {

            myBrush = new LinearGradientBrush(new Rectangle(20, y, 100, 60), Color.Blue, Color.White, gradientStyle);

            g.FillRectangle(myBrush, 20, y, 100, 60);

            g.DrawString(gradientStyle.ToString(), new Font("Tahoma", 8), Brushes.Black, 130, y + 20);

            y += 70;

        }

        image.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);//保存图像

        g.Dispose();//释放图像资源

        image.Dispose();//释放位图占有的资源

    }

}