对24位bmp位图文件进行jpg的压缩

传出的参数：outdata 压缩后数据内存指针 nSize 压缩后数据的大小

传入参数：bmp文件的内存数据 以及文件信息

需要 jconfig.h jmorecfg.h jpeglib.h libjpeg.lib 文件支持

void BmptoJpg(BYTE* &outdata,int &nSize,BITMAP m_bmpBit1,BYTE* m_pBmpData1,BITMAPINFO BitmapInfo)  //返回压缩后jpg数据，数据的大小

{

  

 int nAdjust24;

 UINT dwRead=0;

  BYTE* pData24;

 nAdjust24 = BitmapInfo.bmiHeader.biWidth*3%4;

 if (nAdjust24) nAdjust24 = 4-nAdjust24;

  pData24 = new BYTE[(BitmapInfo.bmiHeader.biWidth*3+nAdjust24)*BitmapInfo.bmiHeader.biHeight];

  for (int j=0;j<BitmapInfo.bmiHeader.biHeight;j++){

   for (int i = 0;i<BitmapInfo.bmiHeader.biWidth;i++)

   {

    BYTE red = m_pBmpData1[j*(BitmapInfo.bmiHeader.biWidth*3+nAdjust24)+i*3];

    m_pBmpData1[j*(BitmapInfo.bmiHeader.biWidth*3+nAdjust24)+i*3] =m_pBmpData1[j*(BitmapInfo.bmiHeader.biWidth*3+nAdjust24)+i*3+2];

    m_pBmpData1[j*(BitmapInfo.bmiHeader.biWidth*3+nAdjust24)+i*3+2] = red;

   }

  }

 struct jpeg_compress_struct jcs;

 struct jpeg_error_mgr jem;

 jcs.err = jpeg_std_error(&jem);

 jpeg_create_compress(&jcs);

 jpeg_stdio_dest(&jcs,(char*)outdata,&nSize);

 jcs.image_width = BitmapInfo.bmiHeader.biWidth;    // 为图的宽和高，单位为像素

 jcs.image_height = BitmapInfo.bmiHeader.biHeight;

 jcs.input_components = 3;   // 1,表示灰度图， 如果是彩色位图，则为3

 jcs.in_color_space = JCS_RGB;

 jpeg_set_defaults(&jcs); 

 jpeg_set_quality (&jcs, 60, true);

 jpeg_start_compress(&jcs, TRUE);

 JSAMPROW row_pointer[1];   // 一行位图

 int row_stride;      // 每一行的字节数

 row_stride = jcs.image_width*3;  // 如果不是索引图,此处需要乘以3

 // 对每一行进行压缩

 while (jcs.next_scanline < jcs.image_height) {

     row_pointer[0] = & m_pBmpData1[(jcs.image_height-jcs.next_scanline-1) * (row_stride+nAdjust24)];

     jpeg_write_scanlines(&jcs, row_pointer, 1);

 }

 jpeg_finish_compress(&jcs);

 jpeg_destroy_compress(&jcs);

 delete [] pData24;

}

 

void JpgtoBmp(BYTE *indata,int nSize,int size,BYTE* &data)  //size为生成bmp文件分配的内存大小，后面已更正了RGB序列，但还存在RGB逆序的错误，使生成的文件                                                                                     //颜色不对，还需改进

{

    BITMAPFILEHEADER bfh;  // bmp文件头

 BITMAPINFOHEADER bih;  // bmp头信息

 RGBQUAD rq[256];   // 调色板

 int nAdjust; // 用于字节对齐

 int nComponent = 0;

 // 声明解压缩对象及错误信息管理器

 struct jpeg_decompress_struct cinfo;

 struct jpeg_error_mgr jerr;

 cinfo.err = jpeg_std_error(&jerr);

 jpeg_create_decompress(&cinfo);

 jpeg_stdio_src(&cinfo,(char*) indata,nSize);

 jpeg_read_header(&cinfo, TRUE);

 nAdjust = cinfo.image_width*cinfo.num_components%4;

 if (nAdjust) nAdjust = 4-nAdjust;

 data = new BYTE[size]; 

 jpeg_start_decompress(&cinfo);

 JSAMPROW row_pointer[1];

 while (cinfo.output_scanline < cinfo.output_height)

 {

  row_pointer[0] = &data[(cinfo.output_height - cinfo.output_scanline-1)*(cinfo.image_width*cinfo.num_components+nAdjust)];

  jpeg_read_scanlines(&cinfo,row_pointer ,

     1);

 }

 jpeg_finish_decompress(&cinfo);

 jpeg_destroy_decompress(&cinfo);

 for (int j=0;j<bih.biHeight;j++)

  for (int i = 0;i<bih.biWidth;i++)

  {

   BYTE red = data[j*(cinfo.image_width*cinfo.num_components+nAdjust)+i*3];

   data[j*(cinfo.image_width*cinfo.num_components+nAdjust)+i*3] = data[j*(cinfo.image_width*cinfo.num_components+nAdjust)+i*3+2];

   data[j*(cinfo.image_width*cinfo.num_components+nAdjust)+i*3+2] = red;

  }

 

}