一般在web应用中,对客户端提交上来的图片肯定需要进行压缩的。尤其是比较大的图片,如果不经过压缩会导致页面变的很大,打开速度比较慢,影响用户体验,所以一般会将图片进行压缩。
代码实现:
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 ImageCompress
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
/// <summary>
/// 无损压缩图片
/// </summary>
/// <param name="sFile">原图片地址(包含图片名称)</param>
/// <param name="dFile">压缩后保存图片地址(包含图片名称)</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="sfsc">是否是第一次调用</param>
/// <returns></returns>
public static bool CompressImage(string sFile, string dFile, int flag = 90, int size = 300, bool sfsc = true)
{
//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(sFile);
if (sfsc == true && firstFileInfo.Length < size * 1024)
{
firstFileInfo.CopyTo(dFile);
return true;
}
Image iSource = Image.FromFile(sFile);
ImageFormat tFormat = iSource.RawFormat;
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(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
FileInfo fi = new FileInfo(dFile);
if (fi.Length > 1024 * size)
{
flag = flag - 10;
CompressImage(sFile, dFile, flag, size, false);
}
}
else
{
ob.Save(dFile, tFormat);
}
return true;
}
catch
{
return false;
}
finally
{
iSource.Dispose();
ob.Dispose();
}
}
private void button1_Click(object sender, EventArgs e)
{
string sfile = @"C:\Users\Mingliang_wang\Pictures\Screenshots\s_test.jpg";
string dfile = @"C:\Users\Mingliang_wang\Pictures\Screenshots\d_test.jpg";
CompressImage(sfile,dfile);
}
}
}
到此这篇关于C#实现无损压缩图片的文章就介绍到这了。希望对大家的学习有所帮助,也希望大家多多支持编程网。