public byte[] ZoomPicture(Image SourceImage, int TargetWidth, int TargetHeight) { int IntWidth; //新的图片宽 int IntHeight; //新的图片高 try { //System.Drawing.Imaging.ImageFormat format = SourceImage.RawFormat; //图片格式 System.Drawing.Bitmap SaveImage = new System.Drawing.Bitmap(TargetWidth, TargetHeight, PixelFormat.Format32bppArgb); Graphics g = Graphics.FromImage(SaveImage); // g.Clear(Color.Transparent); g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; //图片质量 //计算缩放图片的大小 if (SourceImage.Width > TargetWidth && SourceImage.Height <= TargetHeight)//宽度比目的图片宽度大,长度比目的图片长度小 { IntWidth = TargetWidth; IntHeight = (IntWidth * SourceImage.Height) / SourceImage.Width; } else if (SourceImage.Width <= TargetWidth && SourceImage.Height > TargetHeight)//宽度比目的图片宽度小,长度比目的图片长度大 { IntHeight = TargetHeight; IntWidth = (IntHeight * SourceImage.Width) / SourceImage.Height; } else if (SourceImage.Width <= TargetWidth && SourceImage.Height <= TargetHeight) //长宽比目的图片长宽都小 { IntHeight = SourceImage.Width; IntWidth = SourceImage.Height; } else//长宽比目的图片的长宽都大 { IntWidth = TargetWidth; IntHeight = (IntWidth * SourceImage.Height) / SourceImage.Width; if (IntHeight > TargetHeight)//重新计算 { IntHeight = TargetHeight; IntWidth = (IntHeight * SourceImage.Width) / SourceImage.Height; } } //绘制图片 g.DrawImage(SourceImage, (TargetWidth - IntWidth) / 2, (TargetHeight - IntHeight) / 2, IntWidth, IntHeight); using(MemoryStream stream = new MemoryStream()) { SaveImage.Save(stream, ImageFormat.Png); //销毁对象 SaveImage.Dispose(); SourceImage.Dispose(); g.Dispose(); return stream.ToArray(); } } catch (Exception ex) { HxSoft.Common.Config.Err(ex); } return null; }
因为我这里需要缓存图片,所有使用了 byte[]作为返回值,如果是存储图片之类的可以直接返回Image类型(fun里面的SaveImage对象)
我这里使用了质量高的效果,如果使用场景都是很小的图片,可以将图片质量降低以换取更高的性能