如何生成这样的缩略图

[clefoo]

原图：

缩略图：

非网络上流传的等比例缩放，这个可以实现窃取掉一部分图片，有什么办法实现呢？

[threenewbee]

伪代码： double 高宽比 = 3.0 / 4.0; if (图片原始的宽 / 高宽比 > 原始图片的高) { // 图片过扁，那么用图片的高，并且切掉左右多余的部分 Rect r; r.Left = (图片原始的宽 - 图片原始的高 * 高宽比) / 2 r.Top = 0 r.Width = 图片原始的高 * 高宽比 r.Height = 原始图片的高 将这个区域的图片缩放 } else { // 图片过瘦，那么用图片的宽，并且切掉上下多于的部分 ... }

[本拉灯]

用Bitmap.Clone(x,y,width,height)就可以

[insus]

Refer: http://www.cnblogs.com/insus/p/3627437.html

[ltj026]

protected virtual Size CalculateDimensions(Size originalSize, int targetSize) { var newSize = new Size(); if (originalSize.Height > originalSize.Width) // portrait { newSize.Width = (int)(originalSize.Width * (float)(targetSize / (float)originalSize.Height)); newSize.Height = targetSize; } else // landscape or square { newSize.Height = (int)(originalSize.Height * (float)(targetSize / (float)originalSize.Width)); newSize.Width = targetSize; } return newSize; } public void NewPicture(byte[] PictureBinary, int offsetX = 0, int offsetY = 0, int targetSize = 0, double matrix = 1) { var picStream = new MemoryStream(PictureBinary); var picBit = new Bitmap(picStream); var newSize = CalculateDimensions(picBit.Size, targetSize); if (newSize.Width < 1) newSize.Width = 1; if (newSize.Height < 1) newSize.Height = 1; var newBitMap = new Bitmap(200, 200);//the new picture size var g = Graphics.FromImage(newBitMap); g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality; g.DrawImage(picBit, offsetX, offsetY, newSize.Width, newSize.Height); string localFilename = string.Format("{0}_{1}.{2}", picture.Id.ToString("10000000"), "combine", lastPart); var ici = GetImageCodecInfoFromExtension(lastPart) ?? GetImageCodecInfoFromMimeType("image/jpeg"); var ep = new EncoderParameters(); ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, this.ImageQuality); newBitMap.Save(Path.Combine(this.LocalThumbImagePath, localFilename), ici, ep); newBitMap.Dispose(); picBit.Dispose(); }

[IE11下面经常卡到爆]

其实还是按宽或高（看是竖形还是横幅的） 等比例缩放 然后将过长或过宽的那一部分剪掉

[木子木啊]

这个好牛叉啊。。 真的可以这样实现吗？