求生成缩略图的代码

[jornchangzheng]

如题，希望大家热心帮忙

[net_xiaojian]

1楼的那个好，我以前测试过，生成的图片小、质量也高。

[Robin]

// <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();
            }
        }

生成高质量缩略图通用函数

[hhhh63]

同意一楼，不过有一点小的建议。
即然是高质量图形，就别用JPG格式了，用PNG比较好，无损压缩。
要是用JPG的话，前面就别用高质量，低速度了。

[kfps8kfps8]

到博客园找去，有很多，肯定有你想要的。

[编程有钱人了]

http://blog.csdn.net/wangjun8868/archive/2008/11/12/3283493.aspx

[slove1116]

收藏

[qinhl99]

http://www.cnblogs.com/ghd258/archive/2006/02/26/337957.html

[wuyq11]

private static void MakeImg(string originalImagePath, string thumbnailPath, int width, int height, string mode)
{
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":
break;
case "W":
toheight = originalImage.Height * width/originalImage.Width;
break;
case "H":
towidth = originalImage.Width * height/originalImage.Height;
break;
case "Cut":
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;
}
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
Graphics g = System.Drawing.Graphics.FromImage(bitmap);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.Transparent);
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow,oh),
GraphicsUnit.Pixel);
try
{
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch(System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}

[ojekleen]

http://blog.csdn.net/ojekleen/archive/2008/08/01/2754255.aspx