截取图片的某个部分(C#源代码)

方法一(get/set pixel)

核心语句：

resultBitmap.SetPixel(x, y, sourceBitmap.GetPixel(offsetX + x, offsetY+y))

代码

   
     

    
      
    
       1 
    
      ///
    
       
    
      <summary>
    
      

    
       2 
    
       
    
      ///
    
       get a certain rectangle part of a known graphic

    
       3 
    
       
    
      ///
    
       
    
      </summary>
    
      

    
       4 
    
       
    
      ///
    
       
    
      <param name="bitmapPathAndName">
    
      path and name of the source graphic
    
      </param>
    
      

    
       5 
    
       
    
      ///
    
       
    
      <param name="width">
    
      width of the part graphic
    
      </param>
    
      

    
       6 
    
       
    
      ///
    
       
    
      <param name="height">
    
      height of the part graphic
    
      </param>
    
      

    
       7 
    
       
    
      ///
    
       
    
      <param name="offsetX">
    
      the width offset in the source graphic
    
      </param>
    
      

    
       8 
    
       
    
      ///
    
       
    
      <param name="offsetY">
    
      the height offset in the source graphic
    
      </param>
    
      

    
       9 
    
       
    
      ///
    
       
    
      <returns>
    
      wanted graphic
    
      </returns>
    
      

    
      10 
    
       
    
       
    
      public
    
       Bitmap GetPartOfImage(
    
      string
    
       bitmapPathAndName, 
    
      int
    
       width, 
    
      int
    
       height,
    
      int
    
       offsetX,
    
      int
    
       offsetY)

    
      11 
    
       {

    
      12 
    
       Bitmap sourceBitmap 
    
      =
    
       
    
      new
    
       Bitmap(bitmapPathAndName);

    
      13 
    
       Bitmap resultBitmap 
    
      =
    
       
    
      new
    
       Bitmap(width, height);

    
      14 
    
       
    
      for
    
       (
    
      int
    
       x 
    
      =
    
       
    
      0
    
      ; x 
    
      <
    
       width; x
    
      ++
    
      )

    
      15 
    
       {

    
      16 
    
       
    
      for
    
       (
    
      int
    
       y 
    
      =
    
       
    
      0
    
      ; y 
    
      <
    
       height; y
    
      ++
    
      )

    
      17 
    
       {

    
      18 
    
       
    
      if
    
       (offsetX 
    
      +
    
       x 
    
      <
    
       sourceBitmap.Size.Width 
    
      &
    
       offsetY 
    
      +
    
       y 
    
      <
    
       sourceBitmap.Size.Height) 

    
      19 
    
       {

    
      20 
    
       resultBitmap.SetPixel(x, y, sourceBitmap.GetPixel(offsetX 
    
      +
    
       x, offsetY
    
      +
    
      y));

    
      21 
    
       }

    
      22 
    
       }

    
      23 
    
       }

    
      24 
    
       
    
      return
    
       resultBitmap;

    
      25 
    
       }
   
     

该方法速度较慢

方法二(graphics.drawimage)

核心代码：

Graphics g = Graphics.FromImage(resultBitmap)

g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel)

代码

   
     

    
      
    
       1 
    
      ///
    
       
    
      <summary>
    
      

    
       2 
    
       
    
      ///
    
       get a certain rectangle part of a known graphic

    
       3 
    
       
    
      ///
    
       
    
      </summary>
    
      

    
       4 
    
       
    
      ///
    
       
    
      <param name="bitmapPathAndName">
    
      path and name of the source graphic
    
      </param>
    
      

    
       5 
    
       
    
      ///
    
       
    
      <param name="width">
    
      width of the part graphic
    
      </param>
    
      

    
       6 
    
       
    
      ///
    
       
    
      <param name="height">
    
      height of the part graphic
    
      </param>
    
      

    
       7 
    
       
    
      ///
    
       
    
      <param name="offsetX">
    
      the width offset in the source graphic
    
      </param>
    
      

    
       8 
    
       
    
      ///
    
       
    
      <param name="offsetY">
    
      the height offset in the source graphic
    
      </param>
    
      

    
       9 
    
       
    
      ///
    
       
    
      <returns>
    
      wanted graphic
    
      </returns>
    
      

    
      10 
    
       
    
       
    
      public
    
       Bitmap GetPartOfImage(
    
      string
    
       bitmapPathAndName, 
    
      int
    
       width, 
    
      int
    
       height, 
    
      int
    
       offsetX, 
    
      int
    
       offsetY)

    
      11 
    
       {

    
      12 
    
       Bitmap sourceBitmap 
    
      =
    
       
    
      new
    
       Bitmap(bitmapPathAndName);

    
      13 
    
       Bitmap resultBitmap 
    
      =
    
       
    
      new
    
       Bitmap(width, height);

    
      14 
    
       
    
      using
    
       (Graphics g 
    
      =
    
       Graphics.FromImage(resultBitmap))

    
      15 
    
       {

    
      16 
    
       Rectangle resultRectangle 
    
      =
    
       
    
      new
    
       Rectangle(
    
      0
    
      , 
    
      0
    
      , Width, height);

    
      17 
    
       Rectangle sourceRectangle 
    
      =
    
       
    
      new
    
       Rectangle(
    
      0
    
      +
    
      offsetX, 
    
      0
    
      +
    
      offsetY, Width, height);

    
      18 
    
       g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel);

    
      19 
    
       }

    
      20 
    
       
    
      return
    
       resultBitmap;

    
      21 
    
       }
   
     

速度较快，可完全鄙视掉方法一