asp.net如何在图片上加水印文字

第一步，添加一个一般处理程序（Handler）,本例是ImageHandler

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net.Mime;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

/// 
/// Summary description for ImageHandler
/// 
public class ImageHandler : IHttpHandler
{
    public ImageHandler()
    {
    }

    public string GetContentType(String path)
    {
        switch (Path.GetExtension(path))
        {
            case ".bmp": return "Image/bmp";
            case ".gif": return "Image/gif";
            case ".jpg": return "Image/jpeg";
            case ".png": return "Image/png";
            default: break;
        }
        return String.Empty;
    }

    public ImageFormat GetImageFormat(String path)
    {
        switch (Path.GetExtension(path).ToLower())
        {
            case ".bmp": return ImageFormat.Bmp;
            case ".gif": return ImageFormat.Gif;
            case ".jpg": return ImageFormat.Jpeg;
            case ".png": return ImageFormat.Png;
            default: return null;
        }
    }

    protected byte[] WatermarkImage(HttpContext context)
    {

        byte[] imageBytes = null;
        if (File.Exists(context.Request.PhysicalPath))
        {
            // Normally you'd put this in a config file somewhere.
            string watermark = "世复检测";

            Image image = Image.FromFile(context.Request.PhysicalPath);

            Graphics graphic;
            if (image.PixelFormat != PixelFormat.Indexed && image.PixelFormat != PixelFormat.Format8bppIndexed && image.PixelFormat != PixelFormat.Format4bppIndexed && image.PixelFormat != PixelFormat.Format1bppIndexed)
            {
                // Graphic is not a Indexed (GIF) image
                graphic = Graphics.FromImage(image);
            }
            else
            {
                /* Cannot create a graphics object from an indexed (GIF) image. 
                 * So we're going to copy the image into a new bitmap so 
                 * we can work with it. */
                Bitmap indexedImage = new Bitmap(image);
                graphic = Graphics.FromImage(indexedImage);

                // Draw the contents of the original bitmap onto the new bitmap. 
                graphic.DrawImage(image, 0, 0, image.Width, image.Height);
                image = indexedImage;
            }
            graphic.SmoothingMode = SmoothingMode.AntiAlias & SmoothingMode.HighQuality;

            Font myFont = new Font("Arial", 15);
            SolidBrush brush = new SolidBrush(Color.FromArgb(255, Color.Red));

            /* This gets the size of the graphic so we can determine 
             * the loop counts and placement of the watermarked text. */
            SizeF textSize = graphic.MeasureString(watermark, myFont);

            //// Write the text across the image. 
            //for (int y = 0; y 

第二步，在web.config里添加如下代码：

    
      -->
            
    

第三步，调试在每一个图片的右下角显示红色的“世复检测”四个字，具体显示请查看如下连接：

点击打开链接