图片缩放的相关处理

图片缩放的相关处理

最近自己做的点东西上用到了图片的处理，不过没有找到合适的图片处理相关算法，倒是找到了几个获取缩略图的算法。代码不长，简单看了看原理也比较简单（其实不是简单是C#的封装的太多了，所以显得比较简单）。既然没有相关的统一调用的代码，索性，我来整理一套相关的处理代码然后公开出来吧。

图片处理的相关分析

其实我要用的图片处理非常简单，就是简单的压缩一下图片。然后把图片设置到对应大小而已。但是对于设置的方式，C#基础的函数中使用的Rect范围设置。这个范围设置计算起来可能相对头疼一些。所以我在考虑要不要让调用者在忽略Rect这个参数的情况愉快的调用接口呢？于是乎，我定义了几个图片缩放类型（Full、Zoom、Overflow、Original）。然后默认的让原始图片的中心点与输出图片的中心点对齐。然后根据缩放类型来对图片进行不同的缩放模式。

缩放模式

1. Full：让图片放弃原来的比例，直接按照目标数据进行拉伸
2. Zoom：让图片保持原有比例，并且保证原始图片在目标图片的正中央，没有图片的位置保留米白色
3. Original：让图片保持原来的大小，输出图片类似于裁剪中间位置某个范围的图片
4. Overflow：让图片保持原来的比例，并且保证输目标是被图片填满的不留空白

调用的范例

ImageHelper.GetInstance().ImageCompress(InputFile, Path.Combine(OutPutPath, item_file), new System.Drawing.Size(500, 300), ImageZoomType.Full, 50);

样品展示

原始图片

Full 300*500 

 

Full 500 * 300

 

Original 300 * 500

 

Original 500 * 300

 

Overflow 300 * 500

 

Overflow 500 * 300

 

Zoom 300 * 500

 

Zoom 500 * 300

存在的不足

1. 压缩没有独到的技术
2. 目前只支持JPEG格式的图片
3. 部分图片进行缩放之后会留下一个1像素浅浅的边

后续的内容

图片处理不光是缩放，还有其他的很多东西比较实用（截图、压缩、按高缩放、按宽缩放、添加水印、添加隐藏水印），我准备把图片常用的相关处理。整理成一个帮助类，方便迁入到各个项目中去。

所以我建立了一个专门的图片处理的开源项目方便后续功能加入，地址如下：http://git.oschina.net/anxin1225/ImageCompress

 

压缩相关的代码

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using System; using System.Collections.Generic; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; using System.IO; using System.Linq; using System.Text; using System.Threading.Tasks;   namespace ImageCompress {     public struct AnchorPoint     {         //public AnchorPoint() : this(0, 0) { }         public AnchorPoint(double x, double y)         {             X = x;             Y = y;         }           public double X, Y;     }       public enum ImageZoomType     {         Full,         Zoom,         Overflow,         Original,     }       public delegate void ImageHandle(Image image, Bitmap bitmap);       public class ImageHelper     {         private ImageHelper() { }           private static ImageHelper _image_helper = null;         private Dictionary<ImageZoomType, ImageHandle> _name_to_handle = new Dictionary<ImageZoomType, ImageHandle>();           public static ImageHelper GetInstance()         {             if (_image_helper == null)             {                 _image_helper = new ImageHelper();                   //填满                 _image_helper._name_to_handle[ImageZoomType.Full] = (image, bitmap) =>                 {                     _image_helper.DrawImage(image, bitmap, new Rectangle(new Point(0, 0), bitmap.Size));                 };                   //原始                 _image_helper._name_to_handle[ImageZoomType.Original] = (image, bitmap) =>                 {                     _image_helper.DrawImage(image, bitmap, 1, new AnchorPoint(0.5, 0.5), new AnchorPoint(0.5, 0.5));                 };                   //溢出                 _image_helper._name_to_handle[ImageZoomType.Overflow] = (image, bitmap) =>                 {                     float proportion_x = (float)bitmap.Width / image.Width;                     float proportion_y = (float)bitmap.Height / image.Height;                     _image_helper.DrawImage(image, bitmap, proportion_x > proportion_y ? proportion_x : proportion_y, new AnchorPoint(0.5, 0.5), new AnchorPoint(0.5, 0.5));                 };                   //缩放                 _image_helper._name_to_handle[ImageZoomType.Zoom] = (image, bitmap) =>                 {                     float proportion_x = (float)bitmap.Width / image.Width;                     float proportion_y = (float)bitmap.Height / image.Height;                     _image_helper.DrawImage(image, bitmap, proportion_x < proportion_y ? proportion_x : proportion_y, new AnchorPoint(0.5, 0.5), new AnchorPoint(0.5, 0.5));                 };             }               return _image_helper;         }           /// <summary>         /// 压缩图片         /// </summary>         /// <param name="source_path">源数据位置</param>         /// <param name="save_path">保存数据位置</param>         /// <param name="save_size">保存图片大小</param>         /// <param name="ztype">缩放模式</param>         /// <param name="flag">图片保存品质</param>         /// <returns>是否完成压缩</returns>         public bool ImageCompress(string source_path, string save_path, Size save_size, ImageZoomType ztype, int flag)         {             bool success = false;               Image source = null;               while (true)             {                 source = LoadImage(source_path);                 if (source == null)                     break;                   Bitmap bitmap = new Bitmap(save_size.Width, save_size.Height);                   if (_name_to_handle.ContainsKey(ztype))                 {                     _name_to_handle[ztype](source, bitmap);                 }                 else                 {                     break;                 }                   success = SaveImage(bitmap, save_path, source.RawFormat, flag);                 break;             }               if (source != null)                 source.Dispose();               return success;         }           public Image LoadImage(string source_path)         {             Image image = null;             while (true)             {                 if (!File.Exists(source_path))                     break;                   try                 {                     image = Image.FromFile(source_path);                 }                 catch                 {                     break;                 }                   break;             }               return image;         }           /// <summary>         /// 将BitMap保存到磁盘上         /// </summary>         /// <param name="image">需要保存的图片</param>         /// <param name="save_path">保存的路径</param>         /// <param name="format">保存格式</param>         /// <param name="flag">保存质量</param>         /// <returns></returns>         public bool SaveImage(Bitmap image, string save_path, ImageFormat format, int flag)         {             //以下代码为保存图片时，设置压缩质量              EncoderParameters ep = new EncoderParameters();             long[] qy = new long[1];             qy[0] = flag;//设置压缩的比例1-100              EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);             ep.Param[0] = eParam;             try             {                 ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();                 ImageCodecInfo jpegICIinfo = null;                 for (int x = 0; x < arrayICI.Length; x++)                 {                     if (arrayICI[x].FormatDescription.Equals("JPEG"))                     {                         jpegICIinfo = arrayICI[x];                         break;                     }                 }                 if (jpegICIinfo != null)                 {                     image.Save(save_path, jpegICIinfo, ep);//dFile是压缩后的新路径                  }                 else                 {                     image.Save(save_path, format);                 }                 return true;             }             catch             {                 return false;             }             finally             {                 image.Dispose();             }         }           /// <summary>         /// 画图         /// </summary>         /// <param name="source">原始图像</param>         /// <param name="output">输出图像</param>         /// <param name="souce_scale">原始图像的缩放值</param>         /// <param name="souce_anchor"></param>         /// <param name="graphics_anchor"></param>         public void DrawImage(Image source, Bitmap output, float souce_scale, AnchorPoint souce_anchor, AnchorPoint graphics_anchor)         {             DrawImage(source, output, souce_scale, souce_anchor, new Point((int)(output.Width * graphics_anchor.X), (int)(output.Height * graphics_anchor.Y)));         }           /// <summary>         /// 画图         /// </summary>         /// <param name="source">原始图像</param>         /// <param name="output">输出凸显</param>         /// <param name="source_scale">图像的所放值</param>         /// <param name="source_anchor">源图像锚点</param>         /// <param name="souce_point">图像位置</param>         public void DrawImage(Image source, Bitmap output, float source_scale, AnchorPoint source_anchor, Point souce_point)         {             var pic_po = new Point((int)(souce_point.X - source.Size.Width * source_scale * source_anchor.X), (int)(souce_point.Y - source.Size.Height * source_scale * source_anchor.Y));             DrawImage(source, output, new Rectangle(pic_po, new Size((int)(source.Width * source_scale), (int)(source.Height * source_scale))));         }           /// <summary>         /// 画图         /// </summary>         /// <param name="source"></param>         /// <param name="output"></param>         /// <param name="rect"></param>         public void DrawImage(Image source, Bitmap output, Rectangle rect)         {             Graphics g = Graphics.FromImage(output);             g.Clear(Color.WhiteSmoke);             g.CompositingQuality = CompositingQuality.HighQuality;             g.SmoothingMode = SmoothingMode.HighQuality;             g.InterpolationMode = InterpolationMode.HighQualityBicubic;             g.DrawImage(source, rect, 0, 0, source.Width, source.Height, GraphicsUnit.Pixel);             g.Dispose();         }     } }

　　

 

PS：为了美观本文中的原始图片并不是原始图片，因为原始图片太大了。会造成页面滑动，所以我上传了一张较小的图片。Git的图片则是原始的图片