C#图片处理---基础

简单的图片剪裁

 using System;
 using System.Drawing;
 using System.Drawing.Drawing2D;
 using System.IO;

 namespace ClassLibrary
 {
     /// <summary>
     /// 图片处理
     /// </summary>
     public static class Img
     {
         #region 图片裁剪
         #region 通过文件路径图片 public static Image ImgCutFromFile
         /// <summary>
         /// 通过文件路径裁剪图片
         /// </summary>
         /// <param name="imgFile">文件路径</param>
         /// <param name="startX">图片左上角X坐标</param>
         /// <param name="startY">图片左上角Y坐标</param>
         /// <param name="width">截取宽度</param>
         /// <param name="height">截取高度</param>
         /// <param name="widthS">图片显示宽度</param>
         /// <param name="heightS">图片显示高度</param>
         /// <returns></returns>
         public static Image ImgCutFromFile(string imgFile, int startX, int startY, int width, int height, int widthS = , int heightS=)
         {

             Image img = Image.FromFile(imgFile);
             if (widthS >  && heightS > )
             {
                 GetXYWH(ref startX, ref startY, ref width, ref height, widthS, heightS, img);
             }
             return ImgCut(img, startX, startY, width, height);
         }
         #endregion

         #region 通过流图片 public static Image ImgCutFromStream
         /// <summary>
         /// 通过流图片
         /// </summary>
         /// <param name="stream">流</param>
         /// <param name="startX">图片左上角X坐标</param>
         /// <param name="startY">图片左上角Y坐标</param>
         /// <param name="width">截取宽度</param>
         /// <param name="height">截取高度</param>
         /// <param name="widthS">图片显示宽度</param>
         /// <param name="heightS">图片显示高度</param>
         /// <returns></returns>
         public static Image ImgCutFromStream(Stream stream, int startX, int startY, int width, int height, int widthS = , int heightS = )
         {
             Image img = Image.FromStream(stream);
             if (widthS >  && heightS > )
             {
                 GetXYWH(ref startX, ref startY, ref width, ref height, widthS, heightS, img);
             }
             return ImgCut(img, startX, startY, width, height);
         }
         #endregion

         #region 获取实际XYWH private static void GetXYWH
         /// <summary>
         /// 获取实际XYWH
         /// </summary>
         /// <param name="startX">图片左上角X坐标</param>
         /// <param name="startY">图片左上角Y坐标</param>
         /// <param name="width">截取宽度</param>
         /// <param name="height">截取高度</param>
         /// <param name="widthS">图片显示宽度</param>
         /// <param name="heightS">图片显示高度</param>
         /// <param name="img"></param>
         private static void GetXYWH(ref int startX, ref int startY, ref int width, ref int height, int widthS, int heightS, Image img)
         {
             /*img.Width / widthS 是实际图片大小与页面显示图片大小比值*/
             startX = Convert.ToInt32(startX * img.Width / widthS);
             startY = Convert.ToInt32(startY * img.Height / heightS);
             width = Convert.ToInt32(width * img.Width / widthS);
             height = Convert.ToInt32(height * img.Height / heightS);
         }
         #endregion

         #region 执行剪裁 public static Image ImgCut
         /// <summary>
         /// 图片裁剪
         /// </summary>
         /// <param name="image">图片</param>
         /// <param name="startX">图片左上角X坐标</param>
         /// <param name="startY">图片左上角Y坐标</param>
         /// <param name="width">截取宽度</param>
         /// <param name="height">截取高度</param>
         /// <returns></returns>
         public static Image ImgCut(Image image, int startX, int startY, int width, int height)
         {
             Image img = image;//获取原始图片
             Image newImg = new Bitmap(width, height);//裁剪后的图片
             Graphics g = Graphics.FromImage(newImg);
             /*设置质量*/
             g.InterpolationMode = InterpolationMode.HighQualityBicubic;
             g.SmoothingMode = SmoothingMode.HighQuality;
             /*图片源位置,图片源大小*/
             Rectangle fromR = new Rectangle(startX, startY, width, height);
             /*绘图位置绘图大小*/
             Rectangle toR = new Rectangle(, , width, height);
             /*画图*/
             g.DrawImage(img, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
             /*释放截图资源*/
             g.Dispose();
             return newImg;
             //newImg.Save(Server.MapPath(""));
             //newImg.Dispose();
         }
         #endregion
         #endregion

         #region 改变图片大小 public static Image ImgSize
         /// <summary>
         /// 改变图片大小
         /// </summary>
         /// <param name="image">图片</param>
         /// <param name="width">新宽度</param>
         /// <param name="height">新高度</param>
         /// <returns></returns>
         public static Image ImgSize(Image image, int width = , int height = )
         {
             Image img = image;//获取原始图片
             Image newImg = new Bitmap(width, height);//裁剪后的图片
             Graphics g = Graphics.FromImage(newImg);
             /*设置质量*/
             g.InterpolationMode = InterpolationMode.HighQualityBicubic;
             g.SmoothingMode = SmoothingMode.HighQuality;
             /*图片源位置,图片源大小*/
             Rectangle fromR = new Rectangle(, , img.Width, img.Height);
             /*绘图位置绘图大小*/
             if (width ==  && height == ) {
                 width = img.Width;
                 height = img.Height;
             }
             Rectangle toR = new Rectangle(, , width, height);
             /*画图*/
             g.DrawImage(img, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
             /*释放截图资源*/
             g.Dispose();
             return newImg;
         }
         #endregion

     }
 }

 Img