C#清晰的图片缩略方案[转载]

C#清晰的图片缩略方案_.net教程网
http://www.soaspx.com/dotnet/csharp/csharp_20091118_1677.html

希望这篇文章能给对于需要经常生成缩略图的朋友提供帮助！

购吧网目前拥有4000余种商品，在售商品超过2000万，其中图片量截至目前已有8G。
目前我们的方案是用单独的文件服务器存放商品的图片，通过file.365goba.com访问。
文件服务器上架一个用于上传图片的WCF服务对上传的图片进行缩略并保存。

购吧网前期的缩略算法用的是网略上广泛流传的三线性插值算法（效果并不是很好），代码如下：

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

namespace Ants.Tools
{
  
    public class Image
    {

        public int Width { get; set; }

        public int Height { get; set; }     
  
        private Image() { }
        public Image(int width, int height)
        {       
            this.Width = width;
            this.Height = height;
        }
         
        public MemoryStream getHightThumb(Stream imgData, string Mode_HW_W_H_Cut)
        {
            MemoryStream result = new MemoryStream();
            System.Drawing.Image.GetThumbnailImageAbort myCallBack = new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallBack);
            try
            {
                System.Drawing.Image originalImage = System.Drawing.Image.FromStream(imgData);

                int X, Y;
                X = Width;
                Y = Height;

                int towidth = X;
                int toheight = Y;

                int x = 0;
                int y = 0;
                int ow = originalImage.Width;
                int oh = originalImage.Height;

                switch (Mode_HW_W_H_Cut)
                {
                    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 * X / originalImage.Width;
                                               break;
                    case "H//指定高，宽按比例                        towidth = originalImage.Width * Y / 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 * Y / towidth;
                            x = 0;
                            y = (originalImage.Height - oh) / 2;
                        }
                        break;
                    default:
                        break;
                }

                System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

                System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

              
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

                g.Clear(System.Drawing.Color.Transparent);

                g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
                    new System.Drawing.Rectangle(x, y, ow, oh),
                    System.Drawing.GraphicsUnit.Pixel);
                bitmap.Save(result, System.Drawing.Imaging.ImageFormat.Jpeg);

            }
            catch
            {
                //do something
            }
            return result;
        }     }
}

此算法可以满足一般的网站的需求，但是作为一个电子商务网站，商品的图片的清晰度直接影响到消费都对此商品的购买欲望。

为了找到更好的方案，终于让我们找到了一个好的组件：MagickNet 这个组件是用C++写的，不过网络上已经有可用的C#调用版，文章的
后我也会给出这个DLL文件，值得一提的是这个组件是开源的。大家可以去研究下。

MagickNet 的功能很多，我这里就贴出一下他的缩略方法的用法（MagickNet 的资料在网上很难早）

using System;
using System.Collections.Generic;
using System.Text;

namespace KeChenDLL
{
    public class UploadFile
    {
        private string _path;//要处理的图片（原图）地址
        public UploadFile(string path)
        {
            this._path = path;
        }
        private UploadFile()
        {
           
        }
        public void ReSize(int width, int height,string SaveToPath)
        {
            MagickNet.Image img = new MagickNet.Image(_path);
            img.Quality = 100;

            System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(_path);
            int x = bitmap.Width;
            int y = bitmap.Height;
            float rank = (float) x/y;
            if (x > y)
            {
                height =Convert.ToInt32(height / rank);
            }
            else
            {
                width =Convert.ToInt32(width * rank);
            }

            img.Resize(new System.Drawing.Size(width, height));
            img.Write(SaveToPath);
            img.Dispose();
        }
    }
}

原创文字只代表本人某一时间内的观点或结论,本人不对涉及到的任何代码担保。转载请标明出处！