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今天在幫青牧弄相簿功能時, 每張相片都需要一張至兩張的縮圖 , 所以我寫了一個簡單的小方法, 按照width的數值 , 照比例的縮小.

程式碼如下

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;

private bool setNewImag(string oldFileName,int width)
{
   string imgPath = "~/UploadFiles/photo/";
   string fileName = oldFileName;

   Image imgSource = Image.FromFile(Server.MapPath(imgPath + fileName));

   int sourceWidth = imgSource.Width;
   int sourceHeight = imgSource.Height;

   int 比例 = (int)(imgSource.Width / width);

   string newImgName = Path.GetFileNameWithoutExtension(fileName) +
       "_new1" + Path.GetExtension(fileName);

   Image newImg0 =
       imgSource.GetThumbnailImage((int)(sourceWidth / 比例),
       (int)(sourceHeight / 比例),
       null, (IntPtr)0);

   Image newImg =
       imgSource.GetThumbnailImage((int)(sourceWidth / 比例),
       (int)(sourceHeight / 比例),
       null, (IntPtr)0);

   newImg.Save(Server.MapPath(imgPath + newImgName));

   return File.Exists(Server.MapPath(imgPath + newImgName));
}

可能你會好奇, 中間我怎麼縮圖兩次,而取第二次呢?

Image newImg0 =
       imgSource.GetThumbnailImage((int)(sourceWidth / 比例),
       (int)(sourceHeight / 比例),
       null, (IntPtr)0);

   Image newImg =
       imgSource.GetThumbnailImage((int)(sourceWidth / 比例),
       (int)(sourceHeight / 比例),
       null, (IntPtr)0);

網路上有人測試過, 用imgSource.GetThumbnailImage(),同一張圖縮兩次,第二次效果比較好?

有興趣的人可以自已玩玩看喔.