C#压缩图片

C#压缩图片

在网上找了好久发现Tinypng是压缩最好的，但是这个东东要收费呀，烦死了，所以又去网上找了写文章最后我整理了一下。发现一个C#压缩代码的好东西：

先上代码，待会上软件
2个版本都搞上来

下面展示的代码是winfrom里面的。
button1_Click 这个方法通过点击界面触发，然后调用把里面的图片压缩，
CompressImage 这个方法就是我们的压缩图片方法，这个方法是在网上其他博客中抄写的。感觉非常棒。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Picture
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string originalFileFullName = @"E:\2.jpg";
            string afterConversionFileFullName = @"E:\5.jpg";
            CompressImage(originalFileFullName, afterConversionFileFullName,99,100);
        }

        /// <summary>
        /// 无损压缩图片
        /// </summary>
        /// <param name="originalFileFullName">原图片地址</param>
        /// <param name="afterConversionFileFullName">压缩后保存图片地址</param>
        /// <param name="flag">压缩质量（数字越小压缩率越高）1-100</param>
        /// <param name="size">压缩后图片的最大大小</param>
        /// <param name="isFirst">是否是第一次调用</param>
        /// <returns></returns>
        public static bool CompressImage(string originalFileFullName, string afterConversionFileFullName, int flag = 90, int size = 300, bool isFirst = true)
        {
            Image iSource = Image.FromFile(originalFileFullName);
            ImageFormat tFormat = iSource.RawFormat;
            //如果是第一次调用，原始图像的大小小于要压缩的大小，则直接复制文件，并且返回true
            FileInfo firstFileInfo = new FileInfo(originalFileFullName);
            if (isFirst == true && firstFileInfo.Length < size * 1024)
            {
                firstFileInfo.CopyTo(afterConversionFileFullName);
                return true;
            }

            int dHeight = iSource.Height / 2;
            int dWidth = iSource.Width / 2;
            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.Width * 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 = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            g.InterpolationMode = System.Drawing.Drawing2D.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(afterConversionFileFullName, jpegICIinfo, ep);
                    FileInfo fi = new FileInfo(afterConversionFileFullName);
                    if (fi.Length > 1024 * size)
                    {
                        flag = flag - 10;
                        CompressImage(originalFileFullName, afterConversionFileFullName, flag, size, false);
                    }
                }
                else
                {
                    ob.Save(afterConversionFileFullName, tFormat);
                }
                return true;
            }
            catch
            {
                return false;
            }
            finally
            {
                iSource.Dispose();
                ob.Dispose();
            }
        }
    }
}