C#生成縮略圖代碼

本文轉載自查看原文 2012-02-29 21:54 13537

/**/ /// <summary>
        /// 生成縮略圖
        /// </summary>
        /// <param name="originalImagePath"> 源圖路徑（物理路徑） </param>
        /// <param name="thumbnailPath"> 縮略圖路徑（物理路徑） </param>
        /// <param name="width"> 縮略圖寬度 </param>
        /// <param name="height"> 縮略圖高度 </param>
        /// <param name="mode"> 生成縮略圖的方式 </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 ": // 指定高寬縮放（可能變形）
                    break;
                case " W ": // 指定寬，高按比例
                   toheight = originalImage.Height * width/originalImage.Width;
                    break;
                case " H ": // 指定高，寬按比例
                   towidth = originalImage.Width * height/originalImage.Height;
                    break;
                case " Cut ": // 指定高寬裁減（不變形）
                    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;
           }

            // 新建一個bmp圖片
           Image bitmap = new System.Drawing.Bitmap(towidth,toheight);

            // 新建一個畫板
           Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            // 設置高質量插值法
           g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            // 設置高質量,低速度呈現平滑程度
           g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            // 清空畫布並以透明背景色填充
           g.Clear(Color.Transparent);

            // 在指定位置並且按指定大小繪制原圖片的指定部分
           g.DrawImage(originalImage, new Rectangle( 0, 0, towidth, toheight),
                new Rectangle(x, y, ow,oh),
               GraphicsUnit.Pixel);

            try
           {
                // 以jpg格式保存縮略圖
               bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
           }
            catch(System.Exception e)
           {
                throw e;
           }
            finally
           {
               originalImage.Dispose();
               bitmap.Dispose();
               g.Dispose();
           }
       }

第二種

4個重載方法,有直接返回Image對象的,有生成縮略圖,並且保存到指定目錄的!

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

/// <summary>
/// 圖片處理類
/// 1、生成縮略圖片或按照比例改變圖片的大小和畫質
/// 2、將生成的縮略圖放到指定的目錄下
/// </summary>
public class ImageClass
{
     public Image ResourceImage;
     private int ImageWidth;
     private int ImageHeight;

     public string ErrMessage;

     /// <summary>
     /// 類的構造函數
     /// </summary>
     /// <param name="ImageFileName"> 圖片文件的全路徑名稱 </param>
     public ImageClass( string ImageFileName)
    {
        ResourceImage=Image.FromFile(ImageFileName);
     ErrMessage= "";
    }

     public bool ThumbnailCallback()
    {
      return false;
    }

     /// <summary>
     /// 生成縮略圖重載方法1，返回縮略圖的Image對象
     /// </summary>
     /// <param name="Width"> 縮略圖的寬度 </param>
     /// <param name="Height"> 縮略圖的高度 </param>
     /// <returns> 縮略圖的Image對象 </returns>
     public Image GetReducedImage( int Width, int Height)
    {
      try
     {
      Image ReducedImage;

      Image.GetThumbnailImageAbort callb= new Image.GetThumbnailImageAbort(ThumbnailCallback);

      ReducedImage=ResourceImage.GetThumbnailImage(Width,Height,callb,IntPtr.Zero);

       return ReducedImage;
     }
      catch(Exception e)
     {
      ErrMessage=e.Message;
          return null;
     }
    }

     /// <summary>
     /// 生成縮略圖重載方法2，將縮略圖文件保存到指定的路徑
     /// </summary>
     /// <param name="Width"> 縮略圖的寬度 </param>
     /// <param name="Height"> 縮略圖的高度 </param>
     /// <param name="targetFilePath"> 縮略圖保存的全文件名，(帶路徑)，參數格式：D:\Images\filename.jpg </param>
     /// <returns> 成功返回true，否則返回false </returns>
     public bool GetReducedImage( 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)
     {
      ErrMessage=e.Message;
       return false;
     }
    }

     /// <summary>
     /// 生成縮略圖重載方法3，返回縮略圖的Image對象
     /// </summary>
     /// <param name="Percent"> 縮略圖的寬度百分比如：需要百分之80，就填0.8 </param>
     /// <returns> 縮略圖的Image對象 </returns>
     public Image GetReducedImage( double Percent)
    {
      try
     {
      Image ReducedImage;

      Image.GetThumbnailImageAbort callb= new Image.GetThumbnailImageAbort(ThumbnailCallback);

      ImageWidth=Convert.ToInt32(ResourceImage.Width*Percent);
      ImageHeight=Convert.ToInt32(ResourceImage.Width*Percent);

      ReducedImage=ResourceImage.GetThumbnailImage(ImageWidth,ImageHeight,callb,IntPtr.Zero);

       return ReducedImage;
     }
      catch(Exception e)
     {
      ErrMessage=e.Message;
       return null;
     }
    }

     /// <summary>
     /// 生成縮略圖重載方法4，返回縮略圖的Image對象
     /// </summary>
     /// <param name="Percent"> 縮略圖的寬度百分比如：需要百分之80，就填0.8 </param>
     /// <param name="targetFilePath"> 縮略圖保存的全文件名，(帶路徑)，參數格式：D:\Images\filename.jpg </param>
     /// <returns> 成功返回true,否則返回false </returns>
     public bool GetReducedImage( double Percent, string targetFilePath)
    {
      try
     {
      Image ReducedImage;

      Image.GetThumbnailImageAbort callb= new Image.GetThumbnailImageAbort(ThumbnailCallback);

      ImageWidth=Convert.ToInt32(ResourceImage.Width*Percent);
      ImageHeight=Convert.ToInt32(ResourceImage.Width*Percent);

      ReducedImage=ResourceImage.GetThumbnailImage(ImageWidth,ImageHeight,callb,IntPtr.Zero);

      ReducedImage.Save(@targetFilePath,ImageFormat.Jpeg);

      ReducedImage.Dispose();

       return true;
     }
      catch(Exception e)
     {
      ErrMessage=e.Message;
       return false;
     }
    }

}

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