图片压缩

图片压缩到小于指定大小，注意是压缩，不是生成缩略片改变大小。

using System;
using System.Collections.Generic;
using System.Linq;
//using System.Text;

using System.IO;
using System.Drawing;
using System.Drawing.Imaging;

using Xunit;

namespace TestOnly
{
    public class TestOnlyFixture
    {
        [Fact]
        public void Compression()
        {
            string fileName = "bg.jpg";
            string filePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, fileName);
            Compression(filePath);
        }

        private void Compression(string filePath)
        {
            FileInfo file = new FileInfo(filePath);
            decimal fileSize = Math.Round((decimal)file.Length / 1024, 1); // KB

            if (fileSize > 60) // Optimazed image shouldn't be more than 60KB
            {
                Image originalImage = Image.FromFile(filePath);
                Bitmap bitmap = new Bitmap(originalImage);

                ImageCodecInfo imageCodecInfo = ImageCodecInfo.GetImageEncoders().FirstOrDefault(it => it.MimeType == "image/jpeg");

                EncoderParameters encoderParameters = new EncoderParameters(1);
                EncoderParameter encoderParameter = new EncoderParameter(Encoder.Quality, 30L);
                encoderParameters.Param[0] = encoderParameter;

                originalImage.Dispose();
                bitmap.Save(filePath, imageCodecInfo, encoderParameters); // Override

                // More than 60KB will compression again
                Compression(filePath);
            }
        }
    }
}

我比较喜欢Xunit，写个项目放那里，需要测试点东西的时候，就开起来用下，很方便。