C#实现对图片文件的压缩、裁剪操作实例

// <param name="ImageFilePathAndName">图片文件的全路径名称</param> 
public Image ResourceImage =Image.FromFile(ImageFilePathAndName); 

/// <summary> 
/// 生成缩略图重载方法1，返回缩略图的Image对象 
/// </summary> 
/// <param name="Width">缩略图的宽度</param> 
/// <param name="Height">缩略图的高度</param> 
/// <returns>缩略图的Image对象</returns> 
public Image GetReducedImage(int Width, int Height) 
{ 
  try 
  { 
 //用指定的大小和格式初始化Bitmap类的新实例 
 Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format32bppArgb); 
 //从指定的Image对象创建新Graphics对象 
 Graphics graphics = Graphics.FromImage(bitmap); 
 //清除整个绘图面并以透明背景色填充 
 graphics.Clear(Color.Transparent); 
 //在指定位置并且按指定大小绘制原图片对象 
 graphics.DrawImage(ResourceImage, new Rectangle(0, 0, Width, Height)); 
 return bitmap; 
  } 
  catch (Exception e) 
  { 
 ErrMessage = e.Message; 
 return null; 
  } 
} 

/// <summary> 
/// 截取图片方法 
/// </summary> 
/// <param name="url">图片地址</param> 
/// <param name="beginX">开始位置-X</param> 
/// <param name="beginY">开始位置-Y</param> 
/// <param name="getX">截取宽度</param> 
/// <param name="getY">截取长度</param> 
/// <param name="fileName">文件名称</param> 
/// <param name="savePath">保存路径</param> 
/// <param name="fileExt">后缀名</param> 
public static string CutImage(string url, int beginX, int beginY, int getX, int getY, string fileName, string savePath, string fileExt) 
{ 
  if ((beginX < getX) && (beginY < getY)) 
  { 
 Bitmap bitmap = new Bitmap(url);//原图 
if (((beginX + getX) <= bitmap.Width) && ((beginY + getY) <= bitmap.Height)) 
 { 
   Bitmap destBitmap = new Bitmap(getX, getY);//目标图 
   Rectangle destRect = new Rectangle(0, 0, getX, getY);//矩形容器 
   Rectangle srcRect = new Rectangle(beginX, beginY, getX, getY); 

   Graphics.FromImage(destBitmap); 
　　　　　　　　　　　　Graphics.DrawImage(bitmap, destRect, srcRect, GraphicsUnit.Pixel); 
    
   ImageFormat format = ImageFormat.Png; 
   switch (fileExt.ToLower()) 
   { 
 case "png": 
   format = ImageFormat.Png; 
   break; 
 case "bmp": 
   format = ImageFormat.Bmp; 
   break; 
 case "gif": 
   format = ImageFormat.Gif; 
   break; 
   } 
   destBitmap.Save(savePath + "//" + fileName , format); 
   return savePath + "\\" + "*" + fileName.Split('.')[0] + "." + fileExt; 
 } 
 else 
 { 
   return "截取范围超出图片范围"; 
 } 
  } 
  else 
  { 
 return "请确认(beginX < getX)&&(beginY < getY)"; 
  } 
}