代码片段记录

第一个：生成高质量缩略图

用数据库保存图片的路径和文件名称，把文件保存在文件夹中. 
//保存在数据库中的文件路径 
ArrayList arrFilePath=new ArrayList(); 
arrFilePath=myCommonMethod.UploadPic(Files,"/UpLoads/UpPicture/"); 
//获取文件名称 
string fileName=arrFilePath[0].SubString(arrFilePath[0].LastIndexOf("/")+1); 
//源图路径（物理路径） 
originalImagePath=Request.PhysicalApplicationPath+"/UpLoads/UpPicture/"+fileName; 
//缩略图路径（物理路径） 
thumbnailPath     =Request.PhysicalApplicationPath+"/UpLoads/UpPicture/"+"thumb_"+fileName; 
//调用生成缩略图方法 
this.MakeThumbnail(originalImagePath,thumbnailPath,120,150, strMode out outthumbnailPath); 
 
#region  生成缩略图  
  ///<summary>  
  /// 生成缩略图  
  /// </summary>  
  /// <param name="originalImagePath">源图路径（物理路径）</param>  
  /// <param name="thumbnailPath">缩略图路径（物理路径）</param>  
  /// <param name="width">缩略图宽度</param>  
  /// <param name="height">缩略图高度</param>  
  /// <param name="mode">生成缩略图的方式</param>      
  public  void MakeThumbnail(string originalImagePath,  string thumbnailPath, int width, int height, string mode out string outthumbnailPath)  
  {  
   System.Drawing.Image originalImage =System.Drawing.Image.FromFile(originalImagePath);  
             
   int towidth = width;  
   int toheight = height;  
         
   int x = 0;  
   int y = 0;  
   int ow = originalImage.Width;  
   int oh = originalImage.Height;         
   switch (mode)  
   {          
    case "HW"://指定高宽缩放（可能变形）                  
     break;  
    case "W"://指定宽，高按比例                      
     toheight = originalImage.Height * width/originalImage.Width;  
     break;  
    case "H"://指定高，宽按比例  
     towidth = originalImage.Width * height/originalImage.Height;                      
     break;          
    case "Cut"://指定高宽裁减（不变形）                  
     if((double)originalImage.Width/(double)originalImage.Height > (double)towidth/(double)toheight)  
     {  
      oh = originalImage.Height;  
      ow = originalImage.Height*towidth/toheight;  
      y = 0;  
      x = (originalImage.Width - ow)/2;  
     }  
     else  
     {  
      ow = originalImage.Width;  
      oh = originalImage.Width*height/towidth;  
      x = 0;  
      y = (originalImage.Height - oh)/2;  
     }  
     break;                      
    default :  
     break;  
   }      
             
   //新建一个bmp图片  
   System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth,toheight); 
   //新建一个画板  
   Graphics g = System.Drawing.Graphics.FromImage(bitmap); 
   //设置高质量插值法  
   g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; 
   //设置高质量,低速度呈现平滑程度  
   g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 
   //清空画布并以透明背景色填充  
   g.Clear(Color.Transparent);         
   //在指定位置并且按指定大小绘制原图片的指定部分  
   g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),  
    new Rectangle(x, y, ow,oh),  
    GraphicsUnit.Pixel); 
   try  
   {              
    //以jpg格式保存缩略图  
    bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);  
    outthumbnailPath=thumbnailPath; 
   }  
   catch(System.Exception e)  
   {  
    throw e;  
   }  
   finally  
   {  
    originalImage.Dispose();  
    bitmap.Dispose();                          
    g.Dispose();  
   }  
  } 

 

第二个：生成验证码

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Web;


public class ValidateCode
    {
        public ValidateCode()
        {
        }
        /// <summary>
        /// 验证码的最大长度
        /// </summary>
        public int MaxLength
        {
            get { return 10; }
        }
        /// <summary>
        /// 验证码的最小长度
        /// </summary>
        public int MinLength
        {
            get { return 1; }
        }
        /// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="length">指定验证码的长度</param>
        /// <returns></returns>
        public string CreateValidateCode(int length)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            string validateNumberStr = "";
            //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }
        /// <summary>
        /// 创建验证码的图片
        /// </summary>
        /// <param name="containsPage">要输出到的page对象</param>
        /// <param name="validateNum">验证码</param>
        public void CreateValidateGraphic(string validateCode,HttpContext context)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的干扰线
                for (int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validateCode, font, brush, 3, 2);
                //画图片的前景干扰点
                for (int i = 0; i < 100; i++)
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                context.Response.Clear();
                context.Response.ContentType = "image/jpeg";
                context.Response.BinaryWrite(stream.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
        /// <summary>
        /// 得到验证码图片的长度
        /// </summary>
        /// <param name="validateNumLength">验证码的长度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
        {
            return (int)(validateNumLength * 12.0);
        }
        /// <summary>
        /// 得到验证码的高度
        /// </summary>
        /// <returns></returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }
    }