关于位图读取函数int Load_Bitmap_File的lseek问题。

事情是这样的，本人在编译3D游戏编程大师技巧中的程序是遇到了一个关于位图读取函数int Load_Bitmap_File的lseek问题。

我使用以下位图读取函数读取位图事报错如下：

int Load_Bitmap_File(BITMAP_FILE_PTR bitmap, char *filename)
{
// this function opens a bitmap file and loads the data into bitmap

int file_handle,  // the file handle
    index;        // looping index

UCHAR   *temp_buffer = NULL; // used to convert 24 bit images to 16 bit
OFSTRUCT file_data;          // the file data information

// open the file if it exists
if ((file_handle = OpenFile(filename,&file_data,OF_READ))==-1)
   return(0);

// now load the bitmap file header
_lread(file_handle, &bitmap->bitmapfileheader,sizeof(BITMAPFILEHEADER));

// test if this is a bitmap file
if (bitmap->bitmapfileheader.bfType!=BITMAP_ID)
   {
   // close the file
   _lclose(file_handle);

   // return error
   return(0);
   } // end if

// now we know this is a bitmap, so read in all the sections

// first the bitmap infoheader

// now load the bitmap file header
_lread(file_handle, &bitmap->bitmapinfoheader,sizeof(BITMAPINFOHEADER));

// now load the color palette if there is one
if (bitmap->bitmapinfoheader.biBitCount == 8)
   {
   _lread(file_handle, &bitmap->palette,MAX_COLORS_PALETTE*sizeof(PALETTEENTRY));

   // now set all the flags in the palette correctly and fix the reversed 
   // BGR RGBQUAD data format
   for (index=0; index < MAX_COLORS_PALETTE; index++)
       {
       // reverse the red and green fields
       int temp_color                = bitmap->palette[index].peRed;
       bitmap->palette[index].peRed  = bitmap->palette[index].peBlue;
       bitmap->palette[index].peBlue = temp_color;
       
       // always set the flags word to this
       bitmap->palette[index].peFlags = PC_NOCOLLAPSE;
       } // end for index

    } // end if

// finally the image data itself
_lseek(file_handle,-(int)(bitmap->bitmapinfoheader.biSizeImage),SEEK_END);

// now read in the image
if (bitmap->bitmapinfoheader.biBitCount==8 || bitmap->bitmapinfoheader.biBitCount==16) 
   {
   // delete the last image if there was one
   if (bitmap->buffer)
       free(bitmap->buffer);

   // allocate the memory for the image
   if (!(bitmap->buffer = (UCHAR *)malloc(bitmap->bitmapinfoheader.biSizeImage)))
      {
      // close the file
      _lclose(file_handle);

      // return error
      return(0);
      } // end if

   // now read it in
   _lread(file_handle,bitmap->buffer,bitmap->bitmapinfoheader.biSizeImage);

   } // end if
else
if (bitmap->bitmapinfoheader.biBitCount==24)
   {
   // allocate temporary buffer to load 24 bit image
   if (!(temp_buffer = (UCHAR *)malloc(bitmap->bitmapinfoheader.biSizeImage)))
      {
      // close the file
      _lclose(file_handle);

      // return error
      return(0);
      } // end if
   
   // allocate final 16 bit storage buffer
   if (!(bitmap->buffer=(UCHAR *)malloc(2*bitmap->bitmapinfoheader.biWidth*bitmap->bitmapinfoheader.biHeight)))
      {
      // close the file
      _lclose(file_handle);

      // release working buffer
      free(temp_buffer);

      // return error
      return(0);
      } // end if

   // now read the file in
   _lread(file_handle,temp_buffer,bitmap->bitmapinfoheader.biSizeImage);

   // now convert each 24 bit RGB value into a 16 bit value
   for (index=0; index < bitmap->bitmapinfoheader.biWidth*bitmap->bitmapinfoheader.biHeight; index++)
       {
       // build up 16 bit color word
       USHORT color;
       
       // build pixel based on format of directdraw surface
       if (dd_pixel_format==DD_PIXEL_FORMAT555)
           {
           // extract RGB components (in BGR order), note the scaling
           UCHAR blue  = (temp_buffer[index*3 + 0] >> 3),
                 green = (temp_buffer[index*3 + 1] >> 3),
                 red   = (temp_buffer[index*3 + 2] >> 3); 
           // use the 555 macro
           color = _RGB16BIT555(red,green,blue);
           } // end if 555
       else
       if (dd_pixel_format==DD_PIXEL_FORMAT565) 
          {
          // extract RGB components (in BGR order), note the scaling
           UCHAR blue  = (temp_buffer[index*3 + 0] >> 3),
                 green = (temp_buffer[index*3 + 1] >> 2),
                 red   = (temp_buffer[index*3 + 2] >> 3);

           // use the 565 macro
           color = _RGB16BIT565(red,green,blue);

          } // end if 565

       // write color to buffer
       ((USHORT *)bitmap->buffer)[index] = color;

       } // end for index

   // finally write out the correct number of bits
   bitmap->bitmapinfoheader.biBitCount=16;

   // release working buffer 
   free(temp_buffer);

   } // end if 24 bit
else
   {
   // serious problem
   return(0);

   } // end else

#if 0
// write the file info out 
printf("\nfilename:%s \nsize=%d \nwidth=%d \nheight=%d \nbitsperpixel=%d \ncolors=%d \nimpcolors=%d",
        filename,
        bitmap->bitmapinfoheader.biSizeImage,
        bitmap->bitmapinfoheader.biWidth,
        bitmap->bitmapinfoheader.biHeight,
        bitmap->bitmapinfoheader.biBitCount,
        bitmap->bitmapinfoheader.biClrUsed,
        bitmap->bitmapinfoheader.biClrImportant);
#endif

// close the file
_lclose(file_handle);

// flip the bitmap
Flip_Bitmap(bitmap->buffer, 
            bitmap->bitmapinfoheader.biWidth*(bitmap->bitmapinfoheader.biBitCount/8), 
            bitmap->bitmapinfoheader.biHeight);

// return success
return(1);

} // end Load_Bitmap_File

编译运行会产生以下问题

 

查lseek函数介绍也没有发现问题。

http://c.biancheng.net/cpp/html/236.html

然后就查找_lseek()函数在新版本有什么变化。没有查到

http://www.educity.cn/wenda/493024.html

去google搜索到许多人遇到问题，但是没有解决办法。

http://www.debugease.com/vc/2006166.html

还搜到一个人说是因为OS是vista也没说具体解决办法。

https://social.msdn.microsoft.com/Forums/vstudio/en-US/2dde18b1-fe36-4679-8ed2-ee61beee4af3/moves-a-file-pointer-to-the-specified-location?forum=vsdebug

最终在百度知道找到一个答案，就说了一句话把lseek（）函数注释掉。。我开始怎么没想到。

 

解决办法：将

_lseek(file_handle,-(int)(bitmap->bitmapinfoheader.biSizeImage),SEEK_END);

注释掉，我也不知道会产生什么影响，但是错误解决了。暂时先这样解决吧