本文实例为大家分享了C#绘制正方形图片的的具体代码，供大家参考，具体内容如下

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace treads
{
  /// <summary>
  /// 制作小正方形
  /// </summary>
  class Class3
  {
    private string srcFileName = @"x";//获取图片的路径
    private string srcFileName1 = @"x";//要保持图片的新路径

   

    /// <summary>
    /// 保存图片
    /// </summary>
    /// <param name="image">Image 对象</param>
    /// <param name="savePath">保存路径</param>
    /// <param name="ici">指定格式的编解码参数</param>
    private static void SaveImage(Image image, string savePath, ImageCodecInfo ici)
    {
      //设置 原图片 对象的 EncoderParameters 对象
      EncoderParameters parameters = new EncoderParameters(1);
      parameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, ((long)100));
      image.Save(savePath, ici, parameters);
      parameters.Dispose();
    }

    /// <summary>
    /// 获取图像编码解码器的所有相关信息
    /// </summary>
    /// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param>
    /// <returns>返回图像编码解码器的所有相关信息</returns>
    private static ImageCodecInfo GetCodecInfo(string mimeType)
    {
      ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
      foreach (ImageCodecInfo ici in CodecInfo)
      {
        if (ici.MimeType == mimeType)
          return ici;
      }
      return null;
    }

    /// <summary>
    /// 计算新尺寸
    /// </summary>
    /// <param name="width">原始宽度</param>
    /// <param name="height">原始高度</param>
    /// <param name="maxWidth">最大新宽度</param>
    /// <param name="maxHeight">最大新高度</param>
    /// <returns></returns>
    private static Size ResizeImage(int width, int height, int maxWidth, int maxHeight)
    {
      //此次2012-02-05修改过=================
      if (maxWidth <= 0)
        maxWidth = width;
      if (maxHeight <= 0)
        maxHeight = height;
      //以上2012-02-05修改过=================
      decimal MAX_WIDTH = (decimal)maxWidth;
      decimal MAX_HEIGHT = (decimal)maxHeight;
      decimal ASPECT_RATIO = MAX_WIDTH / MAX_HEIGHT;

      int newWidth, newHeight;
      decimal originalWidth = (decimal)width;
      decimal originalHeight = (decimal)height;

      if (originalWidth > MAX_WIDTH || originalHeight > MAX_HEIGHT)
      {
        decimal factor;
        // determine the largest factor 
        if (originalWidth / originalHeight > ASPECT_RATIO)
        {
          factor = originalWidth / MAX_WIDTH;
          newWidth = Convert.ToInt32(originalWidth / factor);
          newHeight = Convert.ToInt32(originalHeight / factor);
        }
        else
        {
          factor = originalHeight / MAX_HEIGHT;
          newWidth = Convert.ToInt32(originalWidth / factor);
          newHeight = Convert.ToInt32(originalHeight / factor);
        }
      }
      else
      {
        newWidth = width;
        newHeight = height;
      }
      return new Size(newWidth, newHeight);
    }

    /// <summary>
    /// 得到图片格式
    /// </summary>
    /// <param name="name">文件名称</param>
    /// <returns></returns>
    public static ImageFormat GetFormat(string name)
    {
      string ext = name.Substring(name.LastIndexOf(".") + 1);
      switch (ext.ToLower())
      {
        case "jpg":
        case "jpeg":
          return ImageFormat.Jpeg;
        case "bmp":
【本文由：日本cn2服务器 提供 转载请保留URL】          return ImageFormat.Bmp;
        case "png":
          return ImageFormat.Png;
        case "gif":
          return ImageFormat.Gif;
        default:
          return ImageFormat.Jpeg;
      }
    }
   

    /// <summary>
    /// 制作小正方形
    /// </summary>
    /// <param name="image">图片对象</param>
    /// <param name="newFileName">新地址</param>
    /// <param name="newSize">长度或宽度</param>
    public static void MakeSquareImage(Image image, string newFileName, int newSize)
    {
      int i = 0;
      int width = image.Width;
      int height = image.Height;
      if (width > height)
        i = height;
      else
        i = width;

      Bitmap b = new Bitmap(newSize, newSize);

      try
      {
        Graphics g = Graphics.FromImage(b);
        //设置高质量插值法
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        //设置高质量,低速度呈现平滑程度
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.PixelOffsetMode = PixelOffsetMode.HighQuality;
        //清除整个绘图面并以透明背景色填充
        g.Clear(Color.Transparent);
        if (width < height)
          g.DrawImage(image, new Rectangle(0, 0, newSize, newSize), new Rectangle(0, (height - width) / 2, width, width), GraphicsUnit.Pixel);
        else
          g.DrawImage(image, new Rectangle(0, 0, newSize, newSize), new Rectangle((width - height) / 2, 0, height, height), GraphicsUnit.Pixel);

        SaveImage(b, newFileName, GetCodecInfo("image/" + GetFormat(newFileName).ToString().ToLower()));
      }
      finally
      {
        image.Dispose();
        b.Dispose();
      }
    }

    /// <summary>
    /// 制作小正方形
    /// </summary>
    /// <param name="fileName">图片文件名</param>
    /// <param name="newFileName">新地址</param>
    /// <param name="newSize">长度或宽度</param>
    public static void MakeSquareImage(string fileName,string newFileName, int newSize)
    {
      MakeSquareImage(Image.FromFile(fileName), newFileName, newSize);
    }
  }
}

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