Question

C# 图像缩略 将图片等比例缩小的500并保存 在线等 急

Answer 1

给你一个曾经写过的文件吧！参数你自己设置

public class ImageUtility
    {
        /// <summary>
        /// 无损压缩图片
        /// </summary>
        /// <param name="sFile">原图片</param>
        /// <param name="dFile">压缩后保存位置</param>
        /// <param name="dHeight">高度</param>
        /// <param name="dWidth">宽度</param>
        /// <param name="flag">压缩质量 1-100</param>
        /// <returns></returns>
        public static bool CompressImage(Stream stream, string dFile, int dHeight, int dWidth, int flag)
        {

            System.Drawing.Image iSource = System.Drawing.Image.FromStream(stream);
            ImageFormat tFormat = iSource.RawFormat;
            int sW = 0, sH = 0;
            //按比例缩放
            Size tem_size = new Size(iSource.Width, iSource.Height);

            if (tem_size.Width > dHeight || tem_size.Width > dWidth)
            {
                if ((tem_size.Width * dHeight) > (tem_size.Height * dWidth))
                {
                    sW = dWidth;
                    sH = (dWidth * tem_size.Height) / tem_size.Width;
                }
                else
                {
                    sH = dHeight;
                    sW = (tem_size.Width * dHeight) / tem_size.Height;
                }
            }
            else
            {
                sW = tem_size.Width;
                sH = tem_size.Height;
            }
            Bitmap ob = new Bitmap(dWidth, dHeight);
            Graphics g = Graphics.FromImage(ob);
            g.Clear(Color.WhiteSmoke);
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;
            g.DrawImage(iSource, new Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
            g.Dispose();
            //以下代码为保存图片时，设置压缩质量
            EncoderParameters ep = new EncoderParameters();
            long[] qy = new long[1];
            qy[0] = flag;//设置压缩的比例1-100
            EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
            ep.Param[0] = eParam;
            try
            {
                ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegICIinfo = null;
                for (int x = 0; x < arrayICI.Length; x++)
                {
                    if (arrayICI[x].FormatDescription.Equals("JPEG"))
                    {
                        jpegICIinfo = arrayICI[x];
                        break;
                    }
                }
                if (jpegICIinfo != null)
                {
                    ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
                }
                else
                {
                    ob.Save(dFile, tFormat);
                }
                return true;
            }
            catch
            {
                return false;
            }
            finally
            {
                iSource.Dispose();
                ob.Dispose();
            }

        }
    }

Answer 2

1楼的太专业了，给你个简单的，我是把宽度设为500，高度按比例缩放。

前面一大段是来设置图片名称和路径的，真正的功能 也就是后6行。

public static void Main(string[] args)
        {
            Console.WriteLine("请输入图片文件路径：");
            string path = Console.ReadLine();
            Console.WriteLine("生的图片将会保存在与原文件相同目录下！");
            string currentPath = path.Substring(0, path.LastIndexOf("\\"));
            string fileName = path.Substring( path.LastIndexOf("\\") + 1 , path.Length - path.LastIndexOf("\\")-1);
            string newFileName = "new" + fileName;
            Image img = Image.FromFile(path);
            int width = 500;
            Image newImg = new Bitmap(width, img.Height * width / img.Width );
            Graphics g = Graphics.FromImage(newImg);
            g.DrawImage(img, 0, 0, width, img.Height * 500 / img.Width);
            newImg.Save(currentPath + newFileName);
        }