好久没写关于C#的博客了~呵呵~前段时间都泡在VC++里面了~
谈到获取缩略图，C#的Image类提供了一个GetThumbnailImage的方法获取，但是我试了一下~得到的缩略图相当模糊~
那怎么获取高清的呢？查了MSDN，拼命死锁后得到这样一个启示：缩略图不就是原图按比例缩小，那我们将原图读入按比例缩放后再在画布上重绘一个不就可以了么？
OK~思路有了~那我们就试试~
下面先贴出Image.GetThumbnailImage的方法：
/// /// 获取源图像的缩略图 /// /// 设置原图的缩略比 /// 原图的路径 /// 要保存的缩略图的路径 /// 表明此次操作是否成功 private bool GetMicroImage(double Percent,string OriginFilePath, string TargetFilePath) { try { Bitmap bt = new Bitmap(120,120); //创建Bitmap实例 Graphics g = Graphics.FromImage(bt); //创建Graphics实例 g.Clear(Color.White); //设置画布背景颜色为白色 g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; Image OrginImage = Image.FromFile(OriginFilePath); //获取源图像的Image实例 Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback); //定义委托 int ImageWidth = Convert.ToInt32(OrginImage.Width * Percent); //设置高度 int ImageHeight = Convert.ToInt32(OrginImage.Height * Percent); //设置宽度 Image MicroImage = OrginImage.GetThumbnailImage(ImageWidth, ImageWidth, callb, IntPtr.Zero); //获取源图像的缩略图 if (ImageWidth > ImageHeight) //如果原图宽度大于高度 { g.DrawImage(MicroImage, 0, (int)(120 - ImageHeight) / 2, ImageWidth, ImageHeight); //缩放图片 } else { g.DrawImage(MicroImage, (int)(120 - ImageWidth) / 2, 0, ImageWidth, ImageHeight); } g.DrawRectangle(new Pen(Color.Gray), 0, 0, 119, 119); //绘制缩略图的边框 bt.Save(TargetFilePath + @"/" + this.OriginFileName.ToString() + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg); //保存缩略图 this.OriginFileName++; bt.Dispose(); //释放对象 MicroImage.Dispose(); OrginImage.Dispose(); return true; } catch(Exception e) { MessageBox.Show("错误信息:" + e.Message, "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Error); return false; } }
然后贴出我写的：
/// /// 高质量缩放图片 /// /// 源图的路径 /// 存储缩略图的路径 /// 缩放后图片宽度 /// 缩放后图片高度 /// 表明此次操作是否成功 private bool GetMicroImage(string OriginFilePath, string TargetFilePath,int DestWidth,int DestHeight) { Image OriginImage = Image.FromFile(OriginFilePath); System.Drawing.Imaging.ImageFormat thisFormat = OriginImage.RawFormat; //按比例缩放 int sW = 0, sH = 0; int ImageWidth = OriginImage.Width; int ImageHeight = OriginImage.Height; if (ImageWidth > DestWidth || ImageHeight > DestHeight) { if ((ImageWidth * DestWidth) > (ImageHeight * DestHeight)) { sW = DestWidth; sH = (DestHeight * ImageHeight) / ImageWidth; } else { sH = DestHeight; sW = (DestWidth * ImageWidth) / ImageHeight; } } else { sW = ImageWidth; sH = ImageHeight; } Bitmap bt = new Bitmap(DestWidth,DestHeight); //根据指定大小创建Bitmap实例 using(Graphics g = Graphics.FromImage(bt)) { g.Clear(Color.White); //设置画布的描绘质量 g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.DrawImage(OriginImage,new Rectangle((DestWidth - sW) / 2,(DestHeight - sH) / 2,sW,sH)); g.Dispose(); } System.Drawing.Imaging.EncoderParameters EncoderParams = new System.Drawing.Imaging.EncoderParameters(); //取得内置的编码器 long[] Quality = new long[1]; Quality[0] = 100; System.Drawing.Imaging.EncoderParameter EncoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality,Quality); EncoderParams.Param[0] = EncoderParam; try { //获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象 System.Drawing.Imaging.ImageCodecInfo[] arrayICI = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders(); System.Drawing.Imaging.ImageCodecInfo jpegICI = null; for (int i = 0; i < arrayICI.Length; i++) { if (arrayICI[i].FormatDescription.Equals("JPEG")) { jpegICI = arrayICI[i]; //设置为JPEG编码方式 break; } } if (jpegICI != null) //保存缩略图 { bt.Save(TargetFilePath + @"/" + this.OriginFileName.ToString() + ".jpg", jpegICI, EncoderParams); } else { bt.Save(TargetFilePath + @"/" + this.OriginFileName.ToString() + ".jpg", thisFormat); } this.OriginFileName++; OriginImage.Dispose(); return true; } catch (System.Runtime.InteropServices.ExternalException e1) //GDI+发生一般错误 { MessageBox.Show("错误信息:" + e1.Message, "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Error); return false; } catch (Exception e2) { MessageBox.Show("错误信息:" + e2.Message, "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Error); return false; } }
OK~大家看看效果吧~嘿嘿~
