基於LibJpeg8d庫的JPG和BMP互轉源碼

附VC編譯的原始碼：

BOOL BmpToJpg( int nWidth, int nHeight, int nPixelBytes, BYTE* byBmpData, BYTE** byJpgData, unsigned long* nSize ){BOOL bResult = FALSE;jpeg_compress_struct jCompress;jpeg_error_mgr       jErrorMgr;jCompress.err = jpeg_std_error( &jErrorMgr );jpeg_create_compress( &jCompress );jpeg_mem_dest( &jCompress, byJpgData, nSize );jCompress.image_width      = nWidth;jCompress.image_height     = nHeight;jCompress.input_components = nPixelBytes;jCompress.in_color_space   = JCS_UNKNOWN;jpeg_set_defaults( &jCompress );jpeg_set_quality ( &jCompress, 70, true );jpeg_start_compress( &jCompress, true );int nLineWidth = nWidth * nPixelBytes;for ( int i = 0; i < nHeight; ++i ){BYTE* lpJpgBits = byBmpData + ( nHeight - i - 1 ) * nLineWidth;JSAMPROW row_pointer = lpJpgBits;jpeg_write_scanlines( &jCompress, &row_pointer, 1 );}jpeg_finish_compress( &jCompress );jpeg_destroy_compress( &jCompress );return bResult;}BOOL JpgToBmp( BYTE* byJpgData, BYTE* byBmpData, unsigned long* nSize ){BOOL bResult = FALSE;jpeg_decompress_struct jDecompress;jpeg_error_mgr         jErrorMgr;jDecompress.err = jpeg_std_error( &jErrorMgr );jpeg_create_decompress( &jDecompress );jpeg_mem_src( &jDecompress, byJpgData, *nSize );jpeg_read_header( &jDecompress, true );jpeg_start_decompress( &jDecompress );int nHeight    = jDecompress.output_height;int nLineWidth = jDecompress.output_components * jDecompress.output_width;for ( int i = 0; i < nHeight; ++i ){BYTE* lpBmBits = byBmpData + ( nHeight - i - 1 ) * nLineWidth;jpeg_read_scanlines( &jDecompress, &lpBmBits, 1 );}jpeg_finish_decompress( &jDecompress );jpeg_destroy_decompress( &jDecompress );*nSize = nLineWidth * nHeight;return bResult;}