需求:图片太大,上传到服务器会非常占用服务器空间,而系统又不要求高清图片,于是就通过递归的方式让图片每次减少10%的大小,当图片大小小于100k的时候就保存在本地,核心代码如下:
class Program { static void Main(string[] args) { byte[] bs = File.ReadAllBytes(@"F:DSCN0361.JPG"); Image img = zipImage(bs); //写入本地 img.Save("DSCN0361.JPG"); Console.WriteLine("转换成功"); Console.Read(); } /// <summary> /// 递归缩小图片,每次缩小到90%大小,当图片大小小于100k时就跳出循环,返回Image对象 /// </summary> /// <param name="bs"></param> /// <returns></returns> static Image zipImage(byte[] bs) { //最大100k if (bs.Length > 1024 * 100) { Image img = Image.FromStream(new MemoryStream(bs)); Bitmap b = new Bitmap((int)(img.Width * 0.9), (int)(img.Height * 0.9)); b.SetResolution(300, 300); Graphics g = Graphics.FromImage(b); g.InterpolationMode = InterpolationMode.HighQualityBicubic; Rectangle recTo = new Rectangle(0, 0, b.Width, b.Height);//表示目标大小 Rectangle recFrom = new Rectangle(0, 0, img.Width, img.Height);//表示源文件大小 g.DrawImage(img, recTo, recFrom, GraphicsUnit.Pixel); g.Dispose(); MemoryStream ms = new MemoryStream(); b.Save(ms, ImageFormat.Jpeg); return zipImage(ms.GetBuffer()); } else { return Image.FromStream(new MemoryStream(bs)); } } }
重点是方法 zipImage