C#图片裁切，生成新图片

        /// 图片裁剪，生成新图，保存在同一目录下,名字加_new，格式1.png  新图1_new.png
        /// </summary>
        /// <param name="picpath">要修改图片完整路径</param>
        /// <param name="x">修改起点x坐标</param>
        /// <param name="y">修改起点y坐标</param>
        /// <param name="width">新图宽度</param>
        /// <param name="height">新图高度</param>
        public static void caijianpic(string picpath, int x, int y, int width, int height)
        {
            //图片路径
            string oldpath = picpath;
            //新图片路径
            string newpath = system.io.path.getextension(oldpath);
            //计算新的文件名，在旧文件名后加_new
            newpath = oldpath.substring(0, oldpath.length - newpath.length) + "_new" + newpath;
            //定义截取矩形
            system.drawing.rectangle croparea = new system.drawing.rectangle(x, y, width, height);
            //要截取的区域大小
            //加载图片
            system.drawing.image img = system.drawing.image.fromstream(new system.io.memorystream(system.io.file.readallbytes(oldpath)));
            //判断超出的位置否
            if ((img.width < x + width) || img.height < y + height)
            {
                messagebox.show("裁剪尺寸超出原有尺寸！");
                img.dispose();
                return;
            }
            //定义bitmap对象
            system.drawing.bitmap bmpimage = new system.drawing.bitmap(img);
            //进行裁剪
            system.drawing.bitmap bmpcrop = bmpimage.clone(croparea, bmpimage.pixelformat);
            //保存成新文件
            bmpcrop.save(newpath);
            //释放对象
            img.dispose(); bmpcrop.dispose();
        }