public static void MakeThumNail(string originalImagePath, string thumNailPath, int width, int height, string model) { System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath); int thumWidth = width; //缩略图的宽度 int thumHeight = height; //缩略图的高度 int x = 0;int y = 0; int originalWidth = originalImage.Width; //原始图片的宽度 int originalHeight = originalImage.Height; //原始图片的高度 switch (model) { case "HW": //指定高宽缩放,可能变形 break; case "W": //指定宽度,高度按照比例缩放 thumHeight = originalImage.Height * width / originalImage.Width; break; case "H": //指定高度,宽度按照等比例缩放 thumWidth = originalImage.Width * height / originalImage.Height; break; case "Cut": if ((double)originalImage.Width / (double)originalImage.Height > (double)thumWidth / (double)thumHeight) { originalHeight = originalImage.Height; originalWidth = originalImage.Height * thumWidth / thumHeight; y = 0; x = (originalImage.Width - originalWidth) / 2; } else{ originalWidth = originalImage.Width; originalHeight = originalWidth * height / thumWidth; x = 0; y = (originalImage.Height - originalHeight) / 2; } break; default: break; } //新建一个bmp图片 System.Drawing.Image bitmap = new System.Drawing.Bitmap(thumWidth, thumHeight); //新建一个画板 System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage(bitmap); //设置高质量查值法 graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量，低速度呈现平滑程度graphic.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //清空画布并以透明背景色填充 graphic.Clear(System.Drawing.Color.Transparent); //在指定位置并且按指定大小绘制原图片的指定部分 graphic.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, thumWidth, thumHeight), new System.Drawing.Rectangle(x, y, originalWidth, originalHeight), System.Drawing.GraphicsUnit.Pixel); try { bitmap.Save(thumNailPath, System.Drawing.Imaging.ImageFormat.Jpeg); } catch (Exception ex) {throw ex; } finally { originalImage.Dispose(); bitmap.Dispose(); graphic.Dispose(); } }