using System; using System.Collections.Generic; using System.Drawing; using System.IO; using System.Linq; using System.Runtime.Serialization.Formatters.Binary; using System.Text; using System.Threading.Tasks; namespace BFKR.Help.IMG { /// <summary> /// 生成缩略图 /// </summary> public class MakeThumbnailImg { public static readonly MakeThumbnailImg Instance = new MakeThumbnailImg(); ///<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 void MakeThumbnail(string originalImagePath, string thumbnailPath, string mode, out string outthumbnailPath, int width=100, int height=100) public byte[] MakeThumbnail(byte[] fileByte, string mode = "Cut", int width = 100, int height = 100) { //Image originalImage = System.Drawing.Image.FromFile(originalImagePath); //MemoryStream memStream = new MemoryStream(fileByte); //BinaryFormatter binFormatter = new BinaryFormatter(); //Image originalImage = (Image)binFormatter.Deserialize(memStream); Image originalImage = null; using (MemoryStream ms = new MemoryStream(fileByte)) { ms.Write(fileByte, 0, fileByte.Length); originalImage = Image.FromStream(ms, true); } 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 Bitmap(towidth, toheight); //新建一个画板 Graphics g = 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); MemoryStream ms = new MemoryStream(); bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); return ms.ToArray(); } catch (System.Exception e) { throw e; } finally { originalImage.Dispose(); bitmap.Dispose(); g.Dispose(); } } } }