利用System.Drawing.Image类进行图片相关操作

2019-11-14 14:03:59

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C#中对图片的操作主要是通过System.Drawing.Image等类进行。

一、将图片转换为字节流

    /// <summary>    /// 图片处理帮助类    /// </summary>    public static class PicPRocessHelper    {        /// <summary>        /// 将图片转换为指定的字节流        /// </summary>        /// <param name="filePath">图片路径</param>        /// <returns>指定的字节流</returns>        public static byte[] ConvertToByte(String filePath)        {            var m = new System.IO.MemoryStream();            var bp = new System.Drawing.Bitmap(filePath);            bp.Save(m, System.Drawing.Imaging.ImageFormat.Jpeg); //将此图像以指定的格式保存到指定的流中。            byte[] imgByte = m.GetBuffer(); //从内存缓冲区中读取            return imgByte;        }    }

二、将字节流转换回图片

        /// <summary>        /// 根据字节流返回Image类型        /// </summary>        /// <param name="streamByte"></param>        /// <returns></returns>        public static Image ReturnImage(byte[] streamByte)        {            System.IO.MemoryStream ms = new System.IO.MemoryStream(streamByte);            Image img = Image.FromStream(ms);            return img;        }

三、将Image对象转换为字节流

        //将Image转换成流数据，并保存为byte[]           public static byte[] PhotoImageInsert(System.Drawing.Image imgPhoto)        {            MemoryStream mstream = new MemoryStream();            imgPhoto.Save(mstream, System.Drawing.Imaging.ImageFormat.Bmp);            byte[] byData = new Byte[mstream.Length];            mstream.Position = 0;            mstream.Read(byData, 0, byData.Length); mstream.Close();            return byData;        }

四、保存图片

            var oldFilename = @"E:/环境部署/图片集/熊猫1.jpg";            var oldImage = System.Drawing.Image.FromFile(oldFilename);            var newFilename = @"E:/我的新熊猫.jpg";            oldImage.Save(newFilename, ImageFormat.Jpeg);

五、生成缩略图

  1         /// <summary>    2         /// 生成图片缩略文件    3         /// </summary>    4         /// <param name="originalImage">图片源文件</param>    5         /// <param name="width">缩略图宽度</param>    6         /// <param name="height">缩略图高度</param>    7         /// <param name="mode">生成缩略图的方式</param>    8         /// <returns>缩率处理后图片文件</returns>   9         public static Image MakeThumbnail(Image originalImage, int width, int height, ThumbnailModel mode) 10         { 11             int towidth = width; 12             int toheight = height; 13  14             int x = 0; 15             int y = 0; 16             int ow = originalImage.Width; 17             int oh = originalImage.Height; 18  19             switch (mode) 20             { 21                 case ThumbnailModel.HighWidth: //指定高宽缩放（可能变形）    22                     break; 23                 case ThumbnailModel.Width: //指定宽，高按比例    24                     toheight = originalImage.Height * width / originalImage.Width; 25                     break; 26                 case ThumbnailModel.Hight: //指定高，宽按比例   27                     towidth = originalImage.Width * height / originalImage.Height; 28                     break; 29                 case ThumbnailModel.Default: //指定高，宽按比例   30                     if (ow <= towidth && oh <= toheight) 31                     { 32                         x = -(towidth - ow) / 2; 33                         y = -(toheight - oh) / 2; 34                         ow = towidth; 35                         oh = toheight; 36                     } 37                     else 38                     { 39                         if (ow > oh)//宽大于高 40                         { 41                             x = 0; 42                             y = -(ow - oh) / 2; 43                             oh = ow; 44                         } 45                         else//高大于宽 46                         { 47                             y = 0; 48                             x = -(oh - ow) / 2; 49                             ow = oh; 50                         } 51                     } 52                     break; 53                 case ThumbnailModel.Auto: 54                     if (originalImage.Width / originalImage.Height >= width / height) 55                     { 56                         if (originalImage.Width > width) 57                         { 58                             towidth = width; 59                             toheight = (originalImage.Height * width) / originalImage.Width; 60                         } 61                         else 62                         { 63                             towidth = originalImage.Width; 64                             toheight = originalImage.Height; 65                         } 66                     } 67                     else 68                     { 69                         if (originalImage.Height > height) 70                         { 71                             toheight = height; 72                             towidth = (originalImage.Width * height) / originalImage.Height; 73                         } 74                         else 75                         { 76                             towidth = originalImage.Width; 77                             toheight = originalImage.Height; 78                         } 79                     } 80                     break; 81                 case ThumbnailModel.Cut: //指定高宽裁减（不变形）    82                     if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) 83                     { 84                         oh = originalImage.Height; 85                         ow = originalImage.Height * towidth / toheight; 86                         y = 0; 87                         x = (originalImage.Width - ow) / 2; 88                     } 89                     else 90                     { 91                         ow = originalImage.Width; 92                         oh = originalImage.Width * height / towidth; 93                         x = 0; 94                         y = (originalImage.Height - oh) / 2; 95                     } 96                     break; 97                 default: 98  99                     break;100             }101 102             //新建一个bmp图片  103             System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);104 105             //新建一个画板  106             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);107 108             //设置高质量插值法  109             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;110 111             //设置高质量,低速度呈现平滑程度  112             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;113 114             //清空画布并以透明背景色填充  115             g.Clear(System.Drawing.Color.White);116 117             //在指定位置并且按指定大小绘制原图片的指定部分  118             g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),119                         new System.Drawing.Rectangle(x, y, ow, oh),120                         System.Drawing.GraphicsUnit.Pixel);121 122             return bitmap;123         }

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其中缩略图模式定义如下：

    /// <summary>    /// 缩率图处理模式    /// </summary>    public enum ThumbnailModel    {        /// <summary>        /// 指定高宽缩放（可能变形）           /// </summary>        HighWidth,        /// <summary>        /// 指定宽，高按比例           /// </summary>        Width,        /// <summary>        /// 默认  全图不变形           /// </summary>        Default,        /// <summary>        /// 指定高，宽按比例        /// </summary>        Hight,        /// <summary>        /// 指定高宽裁减（不变形）？？指定裁剪区域        /// </summary>        Cut,        /// <summary>        /// 自动 原始图片按比例缩放        /// </summary>        Auto    }