using System;
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using System.Collections.Generic;
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using System.Drawing;
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using System.Drawing.Imaging;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Pcb.Common.Utilities
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{
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public class ImageUtility
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{
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public static void CompressionAndSaveImage(System.Web.HttpPostedFile file, string savePath, int width = 640, int height = 360, int Level = 80, bool CompressionAlways = false)
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{
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if (Level < 0 || Level > 100)
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throw new Exception("压缩率必须在0-100之间");
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// Get a bitmap.
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if (file.ContentLength <= 30 * 1024 && !CompressionAlways)
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{
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file.SaveAs(savePath);
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return;
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}
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Image bmpOld = Image.FromStream(file.InputStream);
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Bitmap img = new Bitmap(bmpOld);
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Bitmap bmp2 = null;
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bmpOld.Dispose();
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if (file.ContentLength > 100 * 1024 || CompressionAlways)
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{
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int srcWidth = img.Width;
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int srcHeight = img.Height;
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int thumbWidth = width;
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int thumbHeight = height;
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ImageWH iwh = GetImageNewWH(srcWidth, srcHeight, width, height);
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thumbWidth = iwh.width;
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thumbHeight = iwh.height;
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if (thumbWidth > width || thumbHeight > height)
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{
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iwh = GetImageNewWH(thumbWidth, thumbHeight, width, height);
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thumbWidth = iwh.width;
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thumbHeight = iwh.height;
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}
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Bitmap bmp = new Bitmap(thumbWidth, thumbHeight);
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//从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。
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System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
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//设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality
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gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
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//gr.SmoothingMode = SmoothingMode.None;
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////下面这个也设成高质量
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gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
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//gr.CompositingQuality = CompositingQuality.HighSpeed;
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////下面这个设成High
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gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
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//gr.InterpolationMode = InterpolationMode.Low;
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gr.Clear(System.Drawing.Color.Transparent);
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img.SetResolution(72, 72);
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//把原始图像绘制成上面所设置宽高的缩小图
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System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, thumbWidth, thumbHeight);
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gr.DrawImage(img, rectDestination, 0, 0, srcWidth, srcHeight, GraphicsUnit.Pixel);
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bmp2 = new Bitmap(bmp);
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bmp.Dispose();
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gr.Dispose();
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}
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else
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bmp2 = img;
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ImageCodecInfo Encoder = null;
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Encoder = GetEncoder(ImageFormat.Jpeg);
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// Create an Encoder object based on the GUID
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// for the Quality parameter category.
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System.Drawing.Imaging.Encoder myEncoder =
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System.Drawing.Imaging.Encoder.Quality;
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// Create an EncoderParameters object.
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// An EncoderParameters object has an array of EncoderParameter
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// objects. In this case, there is only one
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// EncoderParameter object in the array.
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EncoderParameters EncoderParameters = new EncoderParameters(1);
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EncoderParameter EncoderParameter = new EncoderParameter(myEncoder, Level);
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EncoderParameters.Param[0] = EncoderParameter;
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bmp2.Save(savePath, Encoder, EncoderParameters);
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bmp2.Dispose();
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img.Dispose();
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}
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private static ImageCodecInfo GetEncoder(ImageFormat format)
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{
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ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
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foreach (ImageCodecInfo codec in codecs)
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{
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if (codec.FormatID == format.Guid)
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return codec;
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}
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return null;
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}
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private static ImageWH GetImageNewWH(int srcWidth, int srcHeight, int width, int height)
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{
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ImageWH iwh = new ImageWH();
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if (srcWidth > width && srcHeight > height)
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{
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if (srcWidth > srcHeight)
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{
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double heightFloat = Convert.ToDouble(srcHeight) / Convert.ToDouble(srcWidth);
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heightFloat = heightFloat * width;
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iwh.height = Convert.ToInt32(heightFloat);
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iwh.width = width;
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}
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else
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{
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double widthFloat = Convert.ToDouble(srcWidth) / Convert.ToDouble(srcHeight);
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widthFloat = widthFloat * height;
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iwh.width = Convert.ToInt32(widthFloat);
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iwh.height = height;
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}
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}
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else if (srcWidth > width)
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{
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double heightFloat = Convert.ToDouble(srcHeight) / Convert.ToDouble(srcWidth);
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heightFloat = heightFloat * width;
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iwh.height = Convert.ToInt32(heightFloat);
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iwh.width = width;
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}
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else if (srcHeight > height)
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{
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double widthFloat = Convert.ToDouble(srcWidth) / Convert.ToDouble(srcHeight);
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widthFloat = widthFloat * height;
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iwh.width = Convert.ToInt32(widthFloat);
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iwh.height = height;
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}
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else
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{
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iwh.width = srcWidth;
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iwh.height = srcHeight;
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}
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return iwh;
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}
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private class ImageWH
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{
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public int width { get; set; }
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public int height { get; set; }
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}
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}
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}
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