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 = 0, int heightS=0)
        {
            
            Image img = Image.FromFile(imgFile);
            if (widthS > 0 && heightS > 0)
            {
                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 = 0, int heightS = 0)
        {
            Image img = Image.FromStream(stream);
            if (widthS > 0 && heightS > 0)
            {
                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(0, 0, 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 = 0, int height = 0)
        {
            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(0, 0, img.Width, img.Height);
            /*绘图位置绘图大小*/
            if (width == 0 && height == 0) {
                width = img.Width;
                height = img.Height;
            }
            Rectangle toR = new Rectangle(0, 0, 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