c#在服务器端处理图像大小(size)

Question

如题,收集相关技术资料,或思路

Answer 1

private void ShowThumbnail(string oldfile, string newfile, int h, int w)
{
   
System.Drawing.Image img = System.Drawing.Image.FromFile(oldfile);
System.Drawing.Image.GetThumbnailImageAbort myCallback = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback); int oldh = img.Height;
int oldw = img.Width; int newh,neww; double h1 = oldh*1.0/h;
double w1 = oldw*1.0/w; double f = (h1>w1)? h1:w1; if(f < 1.0)
{
newh = oldh;
neww = oldw;
}
else
{
newh = (int)(oldh/f);
neww = (int)(oldw/f);
} System.Drawing.Image myThumbnail = img.GetThumbnailImage(neww, newh, myCallback, IntPtr.Zero); myThumbnail.Save(newfile, System.Drawing.Imaging.ImageFormat.Jpeg); img.Dispose();
myThumbnail.Dispose();
}
private bool ThumbnailCallback()
{
return false;
}

Answer 2

Bitmap   myBitmap   =   new   Bitmap("Runner.jpg");     
    
  //   One   hand   of   the   runner   
  Rectangle   sourceRectangle   =   new   Rectangle(80,   70,   80,   45);   
    
  //   Compressed   hand   
  Rectangle   destRectangle1   =   new   Rectangle(200,   10,   20,   16);   
    
  //   Expanded   hand   
  Rectangle   destRectangle2   =   new   Rectangle(200,   40,   200,   160);   
    
  //   Draw   the   original   image   at   (0,   0).   
  myGraphics.DrawImage(myBitmap,   0,   0);   
    
  //   Draw   the   compressed   hand.   
  myGraphics.DrawImage(   
        myBitmap,   destRectangle1,   sourceRectangle,   GraphicsUnit.Pixel);   
    
  //   Draw   the   expanded   hand.     
  myGraphics.DrawImage(   
        myBitmap,   destRectangle2,   sourceRectangle,   GraphicsUnit.Pixel);

Answer 3

上面是压缩　尺寸不变这个是缩略图变长和宽的ImageThumbnail.cs
using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;public class ImageThumbnail
{
     public Image ResourceImage;
     private int ImageWidth;
     private int ImageHeight;
     public string ErrorMessage;     public ImageThumbnail(string ImageFileName)
     {
         ResourceImage = Image.FromFile(ImageFileName);
         ErrorMessage = "";
     }     public bool ThumbnailCallback()
     {
         return false;
     }
     // 方法1，按大小
     public bool ReducedImage(int Width, int Height, string targetFilePath)
     {
         try
         {
             Image ReducedImage;
             Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
             ReducedImage = ResourceImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);
             ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);
             ReducedImage.Dispose();
             return true;
         }
         catch (Exception e)
         {
             ErrorMessage = e.Message;
             return false;
         }
     }
     // 方法2，按百分比   缩小60% Percent为0.6 targetFilePath为目标路径
     public bool ReducedImage(double Percent, string targetFilePath)
     {
         try
         {
             Image ReducedImage;
             Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
             ImageWidth = Convert.ToInt32(ResourceImage.Width * Percent);
             ImageHeight = (ResourceImage.Height)*ImageWidth/ ResourceImage.Width;//等比例缩放
             ReducedImage = ResourceImage.GetThumbnailImage(ImageWidth, ImageHeight, callb, IntPtr.Zero);
             ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);
             ReducedImage.Dispose();
             return true;
         }
         catch (Exception e)
         {
             ErrorMessage = e.Message;
             return false;
         }
     }
}后台代码：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class _Default : System.Web.UI.Page
{     protected void Page_Load(object sender, EventArgs e)
     {     }
     protected void bt_upload_Click(object sender, EventArgs e)
     {
         try
         {
             if (FileUpload1.PostedFile.FileName == "")
             {
                 this.lb_info.Text = "请选择文件！";
             }
             else
             {
                 string filepath = FileUpload1.PostedFile.FileName;
                 string filename = filepath.Substring(filepath.LastIndexOf("\\") + 1);
                 string serverpath1 = Server.MapPath("images/") + filename;
                 string serverpath2 = Server.MapPath("images/") + System.DateTime.Now.ToString("yyy-MM-dd-hh-mm-ss") + Session.SessionID + filename;
                 FileUpload1.PostedFile.SaveAs(serverpath1);
                 ImageThumbnail img = new ImageThumbnail(filepath);
                 img.ReducedImage(0.4, serverpath2);//0.4表示缩小40%
                 this.lb_info.Text = "上传成功！";
             }
         }
         catch (Exception error)
         {
             this.lb_info.Text = "上传发生错误！原因：" + error.ToString();
         }
     }
}

Answer 4

/**//// <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 static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
       {
           Image originalImage = 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
           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);
           }
           catch(System.Exception e)
           {
               throw e;
           }
           finally
           {
               originalImage.Dispose();
               bitmap.Dispose();                        
               g.Dispose();
           }
       } 我收藏一下这个代码,