使用c#生成高品质小空间的缩略图

.Net自带的生成缩略图的方法是Bitmap.GetThumbnailImage这个方法生成的缩略图不够清 晰，一般我们会使用Graphics高质量插值发生成清晰的缩略图，这时候大小会不尽人意，怎 么办？我们可以使用jpeg压缩的方法压缩一下图片，这样图片的大小会缩小到压缩前的十分 之一。

下面是完成这项工作的代码：

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:\photoes\20060725\Picture 057.jpg";            string targetFolder = @"E:\Diary\Test\thumbnail";            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, 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));                }                // original code that creates lousy thumbnails                   // System.Drawing.Image ret = source.GetThumbnailImage(wi,hi,null,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, 0, 0, wi, hi);                        g.DrawImage(source, 0, 0, wi, 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, 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,hi,null,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, 0, 0, wi, hi);                        g.DrawImage(source, 0, 0, wi, hi);                    }                    string targetPath = Path.Combine(targetFolder, "th_3.jpg");                    thumb.Save(targetPath, jpegICI, encoderParams);                }            }        }    }}

以上是小编为您精心准备的的内容，在的博客、问答、公众号、人物、课程等栏目也有的相关内容，欢迎继续使用右上角搜索按钮进行搜索string
， bitmap
， sources
， using
， system
， source
， source insightc++
， height
hi
c chart控件使用、c 定时器的使用、c try catch的使用、c 类的使用、dev c 使用教程，以便于您获取更多的相关知识。