using System; using System.Collections.Generic; using System.Web; using System.Drawing.Imaging; using System.Drawing; /// <SUMMARY> ///MakeThum 的摘要说明 /// </SUMMARY> public class MakeThum { public MakeThum() { // //TODO: 在此处添加构造函数逻辑 // } /// <SUMMARY> /// 生成缩略图//带压缩图片不压缩22k压缩2k /// </SUMMARY> /// <PARAM name="originalImagePath" />原始路径 /// <PARAM name="thumbnailPath" />生成缩略图路径 /// <PARAM name="width" />缩略图的宽 /// <PARAM name="height" />缩略图的高 //是否压缩图片质量 public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, bool Ys) { //获取原始图片 System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath); //缩略图画布宽高 int towidth = width; int toheight = height; //原始图片写入画布坐标和宽高(用来设置裁减溢出部分) int x = 0; int y = 0; int ow = originalImage.Width; int oh = originalImage.Height; //原始图片画布,设置写入缩略图画布坐标和宽高(用来原始图片整体宽高缩放) int bg_x = 0; int bg_y = 0; int bg_w = towidth; int bg_h = toheight; //倍数变量 double multiple = 0; //获取宽长的或是高长与缩略图的倍数 if (originalImage.Width >= originalImage.Height) multiple = (double)originalImage.Width / (double)width; else multiple = (double)originalImage.Height / (double)height; //上传的图片的宽和高小等于缩略图 if (ow <= width && oh <= height) { //缩略图按原始宽高 bg_w = originalImage.Width; bg_h = originalImage.Height; //空白部分用背景色填充 bg_x = Convert.ToInt32(((double)towidth - (double)ow) / 2); bg_y = Convert.ToInt32(((double)toheight - (double)oh) / 2); } //上传的图片的宽和高大于缩略图 else { //宽高按比例缩放 bg_w = Convert.ToInt32((double)originalImage.Width / multiple); bg_h = Convert.ToInt32((double)originalImage.Height / multiple); //空白部分用背景色填充 bg_y = Convert.ToInt32(((double)height - (double)bg_h) / 2); bg_x = Convert.ToInt32(((double)width - (double)bg_w) / 2); } //新建一个bmp图片,并设置缩略图大小. System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight); //新建一个画板 System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap); //设置高质量插值法 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBilinear; //设置高质量,低速度呈现平滑程度 g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //清空画布并设置背景色 g.Clear(System.Drawing.ColorTranslator.FromHtml("#FFF")); //在指定位置并且按指定大小绘制原图片的指定部分 //第一个System.Drawing.Rectangle是原图片的画布坐标和宽高,第二个是原图片写在画布上的坐标和宽高,最后一个参数是指定数值单位为像素 g.DrawImage(originalImage, new System.Drawing.Rectangle(bg_x, bg_y, bg_w, bg_h), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel); if (Ys) { System.Drawing.Imaging.ImageCodecInfo encoder = GetEncoderInfo("image/jpeg"); try { if (encoder != null) { System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters(1); //设置 jpeg 质量为 60 encoderParams.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)60); bitmap.Save(thumbnailPath, encoder, encoderParams); encoderParams.Dispose(); } } catch (System.Exception e) { throw e; } finally { originalImage.Dispose(); bitmap.Dispose(); g.Dispose(); } } else { try { //获取图片类型 string fileExtension = System.IO.Path.GetExtension(originalImagePath).ToLower(); //按原图片类型保存缩略图片,不按原格式图片会出现模糊,锯齿等问题. switch (fileExtension) { case ".gif": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif); break; case ".jpg": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); break; case ".bmp": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp); break; case ".png": bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png); break; } } catch (System.Exception e) { throw e; } finally { originalImage.Dispose(); bitmap.Dispose(); g.Dispose(); } } } private System.Drawing.Imaging.ImageCodecInfo GetEncoderInfo(string mimeType) { //根据 mime 类型，返回编码器 System.Drawing.Imaging.ImageCodecInfo result = null; System.Drawing.Imaging.ImageCodecInfo[] encoders = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders(); for (int i = 0; i < encoders.Length; i++) { if (encoders[i].MimeType == mimeType) { result = encoders[i]; break; } } return result; } } if (FileUpload1.HasFile) { string _fileName = FileUpload1.FileName; string _fileExt = System.IO.Path.GetExtension(_fileName); string _webRoot = Server.MapPath("~"); string _imgOriginPath = _webRoot + "/newimage/" + Guid.NewGuid().ToString() + _fileExt; FileUpload1.SaveAs(_imgOriginPath); new MakeThum().MakeThumbnail(_imgOriginPath, _webRoot + "/newimage/" + DateTime.Now.ToString("yyyyMMddHHmmssffff") + _fileExt, 100, 100, false); new MakeThum().MakeThumbnail(_imgOriginPath, _webRoot + "/newimage/ys" + DateTime.Now.ToString("yyyyMMddHHmmssffff") + _fileExt, 100, 100, true); }