生成高品质小空间的缩略图C#代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.IO;

namespace ConsoleApplication3_ThumbnailImg
{
    class Program
    {
        const int HEIGHT = 190;
        const int WIDTH = 190;
        static void Main(string[] args)
        {
            string srcImgPath = @"G:photoes20060725Picture 057.jpg";
            string targetFolder = @"E:DiaryTestthumbnail";

            SetThumbnail_1(srcImgPath,targetFolder);
            SetThumbnail_2(srcImgPath,targetFolder);
            SetThumbnail_3(srcImgPath,targetFolder);

            Console.Read();
        }

        static void SetThumbnail_1(string srcImgPath,string targetFolder)
        {
            using (Bitmap source = new Bitmap(srcImgPath))
            {
                // return the source image if it's smaller than the designated thumbnail   
                int wi,hi;
                wi = WIDTH;
                hi = HEIGHT;

                // maintain the aspect ratio despite the thumbnail size parameters   
                if (source.Width > source.Height)
                {
                    wi = WIDTH;
                    hi = (int)(source.Height * ((decimal)WIDTH / source.Width));
                }
                else
                {
                    hi = HEIGHT;
                    wi = (int)(source.Width * ((decimal)HEIGHT / source.Height));
                }

                using (Image thumb = source.GetThumbnailImage(wi,hi,null,IntPtr.Zero))
                {
                    string targetPath = Path.Combine(targetFolder,"th_1.jpg");
                    thumb.Save(targetPath);
                }
            }
        }

        static void SetThumbnail_2(string srcImgPath,hi;
                wi = WIDTH;
                hi = HEIGHT;

                // maintain the aspect ratio despite the thumbnail size parameters   
                if (source.Width > source.Height)
                {
                    wi = WIDTH;
                    hi = (int)(source.Height * ((decimal)WIDTH / source.Width));
                }
                else
                {
                    hi = HEIGHT;
                    wi = (int)(source.Width * ((decimal)HEIGHT / source.Height));
                }

                // original code that creates lousy thumbnails   
                // System.Drawing.Image ret = source.GetThumbnailImage(wi,IntPtr.Zero);   
                using (System.Drawing.Bitmap thumb = new Bitmap(wi,hi))
                {
                    using (Graphics g = Graphics.FromImage(thumb))
                    {
                        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        g.FillRectangle(Brushes.White,wi,hi);
                        g.DrawImage(source,hi);
                    }
                    string targetPath = Path.Combine(targetFolder,"th_2.jpg");
                    thumb.Save(targetPath);
                }

            }
        }

        static void SetThumbnail_3(string srcImgPath,string targetFolder)
        {
            //Configure JPEG Compression Engine   
            System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters();
            long[] quality = new long[1];
            quality[0] = 75;
            System.Drawing.Imaging.EncoderParameter encoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality,quality);
            encoderParams.Param[0] = encoderParam;

            System.Drawing.Imaging.ImageCodecInfo[] arrayICI = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();
            System.Drawing.Imaging.ImageCodecInfo jpegICI = null;
            for (int x = 0; x < arrayICI.Length; x++)
            {
                if (arrayICI[x].FormatDescription.Equals("JPEG"))
                {
                    jpegICI = arrayICI[x];
                    break;
                }
            }

            using (Bitmap source = new Bitmap(srcImgPath))
            {
                int wi,"th_3.jpg");
                    thumb.Save(targetPath,jpegICI,encoderParams);
                }

            }

        }
    }
}