public class ImagesHelper { /// <summary> /// 缩略图1:生成等比例高清缩略图，图片比较大 /// </summary> /// <param name="phyPath">原图片的路径</param> /// <param name="width">缩略图宽</param> /// <param name="height">缩略图高</param> /// <returns></returns> public static System.Drawing.Image GetThumbnailImage(System.Drawing.Image image, int width, int height) { Bitmap bmp = new Bitmap(width, height); //从Bitmap创建一个System.Drawing.Graphics System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp); //设置 gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //设成高质量 gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; //设成High gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; //把原始图像绘制成上面所设置宽高的缩小图 System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, width, height); gr.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel); return bmp; } /// <summary> /// 缩略图2：得到指定像素缩略图，图片比较小 /// </summary> /// <param name="Image"></param> /// <param name="newFile"></param> /// <param name="maxHeight"></param> /// <param name="maxWidth"></param> /// <param name="qualityNum">图片质量1-100</param> /// <param name="mode">缩放模式，CUT裁剪不失真，HW定宽高有可能变形，W定宽，H定高</param> public static void GetSmallImage(Image img, string newFile, int maxHeight, int maxWidth, long qualityNum, string mode) { System.Drawing.Imaging.ImageFormat thisFormat = img.RawFormat; int towidth = maxWidth; int toheight = maxHeight; int x = 0; int y = 0; int ow = img.Width; int oh = img.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 = img.Height * maxWidth / img.Width; break; case "H"://指定高，宽按比例 towidth = img.Width * maxHeight / img.Height; break; case "CUT"://指定高宽裁减（不变形） if ((double)img.Width / (double)img.Height > (double)towidth / (double)toheight) { oh = img.Height; ow = img.Height * towidth / toheight; y = 0; x = (img.Width - ow) / 2; } else { ow = img.Width; oh = img.Width * maxHeight / towidth; x = 0; y = (img.Height - oh) / 2; } break; default: break; } Bitmap outBmp = new Bitmap(towidth, toheight); Graphics g = Graphics.FromImage(outBmp); // 设置画布的描绘质量 g.CompositingQuality = CompositingQuality.HighQuality; g.SmoothingMode = SmoothingMode.HighQuality; g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(img, new Rectangle(0, 0, towidth, toheight), x, y, ow, oh, GraphicsUnit.Pixel); g.Dispose(); // 以下代码为保存图片时,设置压缩质量 EncoderParameters encoderParams = new EncoderParameters(); long[] quality = new long[1]; quality[0] = qualityNum;//图片质量1-100 EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality); encoderParams.Param[0] = encoderParam; //获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象. ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo jpegICI = null; for (int index = 0; index < arrayICI.Length; index++) { if (arrayICI[index].FormatDescription.Equals("JPEG")) { jpegICI = arrayICI[index]; //设置JPEG编码 break; } } if (jpegICI != null) { outBmp.Save(newFile, jpegICI, encoderParams); } else { outBmp.Save(newFile, thisFormat); } img.Dispose(); outBmp.Dispose(); } #region 图片旋转函数 /// <summary> /// 以逆时针或顺时针方向对图像进行旋转 /// </summary> /// <param name="imgFilePath">图片的物理路基</param> /// <param name="angle">1-360刻度</param> /// <returns></returns> public static Bitmap Rotate(string imgFilePath, int angle) { var b = new Bitmap(imgFilePath); return Rotate(b, angle, imgFilePath); } /// <summary> /// 图片向左旋转90度 /// </summary> /// <param name="imgFilePath">图片物理路径</param> /// <param name="angle">旋转度数</param> /// <returns>成功返回true，失败返回false</returns> public static bool RotateLeft(string imgFilePath, int angle = 90) { try { Rotate(imgFilePath, angle); } catch (Exception) { return false; } return true; } /// <summary> /// 图片向右旋转90度 /// </summary> /// <param name="imgFilePath">图片物理路径</param> /// <param name="angle">旋转度数</param> /// <returns>成功返回true，失败返回false</returns> public static bool RotateRight(string imgFilePath, int angle = 270) { try { Rotate(imgFilePath, angle); } catch (Exception) { return false; } return true; } /// <summary> /// 以逆时针或顺时针方向对图像进行旋转 /// </summary> /// <param name="bitmap">Bitmap图片类型</param> /// <param name="angle">1-360刻度</param> /// <param name="imgFilePath">保存图片路径,可选项</param> /// <returns></returns> private static Bitmap Rotate(Image bitmap, int angle, string imgFilePath = "") { angle = angle > 0 ? angle : angle + 360; angle = angle % 360; //弧度转换 var radian = angle * Math.PI / 180.0; var cos = Math.Cos(radian); var sin = Math.Sin(radian); //原图的宽和高 var w = bitmap.Width; var h = bitmap.Height; var W = (int)(Math.Max(Math.Abs(w * cos - h * sin), Math.Abs(w * cos + h * sin))); var H = (int)(Math.Max(Math.Abs(w * sin - h * cos), Math.Abs(w * sin + h * cos))); //目标位图 var dsImage = new Bitmap(W, H); var g = Graphics.FromImage(dsImage); g.InterpolationMode = InterpolationMode.Bilinear; g.SmoothingMode = SmoothingMode.HighQuality; //计算偏移量 var offset = new Point((W - w) / 2, (H - h) / 2); //构造图像显示区域：让图像的中心与窗口的中心点一致 var rect = new Rectangle(offset.X, offset.Y, w, h); var center = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2); g.TranslateTransform(center.X, center.Y); g.RotateTransform(360 - angle); //恢复图像在水平和垂直方向的平移 g.TranslateTransform(-center.X, -center.Y); g.DrawImage(bitmap, rect); //重至绘图的所有变换 g.ResetTransform(); g.Save(); g.Dispose(); bitmap.Dispose(); if (imgFilePath != "") dsImage.Save(imgFilePath); return dsImage; } #endregion 图片旋转函数 /// <summary> /// 向图片中添加水印 /// </summary> /// <param name="image">上传图片对象</param> /// <param name="waterFilePath">水印图片物理路径</param> public static Image AddWater(Image image, string waterFilePath) { if (image == null) return null; var waterImage = Image.FromFile(waterFilePath, false); if (image.Width <= waterImage.Width) { return image; } //Imaging.Encoder.Quality 默认为60 指定的数字越小，压缩的级别就越高 最大为100L 质量最佳 var g = Graphics.FromImage(image); //设置高质量插值法 g.InterpolationMode = InterpolationMode.HighQualityBicubic; //设置高质量,低速度呈现平滑程度 g.SmoothingMode = SmoothingMode.HighQuality; g.CompositingQuality = CompositingQuality.HighQuality; g.DrawImage(waterImage, new Rectangle((image.Width - waterImage.Width) - 10, (image.Height - waterImage.Height) - 10, waterImage.Width, waterImage.Height), 0, 0, waterImage.Width, waterImage.Height, GraphicsUnit.Pixel); g.Dispose(); return image; } }