ximajpg.cpp

信息隐藏中用于数字隐写的常用算法:LSB替换LSB匹配,包括随机的和排序的,以及对文件和文件夹进行操作,用CxImage类能快速读取各种格式的图象

				dst[x3]  =(BYTE)((k * src[x4+2])/255);
				dst[x3+1]=(BYTE)((k * src[x4+1])/255);
				dst[x3+2]=(BYTE)((k * src[x4+0])/255);
			}
		} else {
			/* Assume put_scanline_someplace wants a pointer and sample count. */
			iter.SetRow(buffer[0], row_stride);
		}
			iter.PrevRow();
	}

	/* Step 7: Finish decompression */
	(void) jpeg_finish_decompress(&cinfo);
	/* We can ignore the return value since suspension is not possible
	* with the stdio data source.
	*/

	//<DP> Step 7A: Swap red and blue components
	// not necessary if swapped red and blue definition in jmorecfg.h;ln322 <W. Morrison>
	if ((cinfo.num_components==3)&&(cinfo.quantize_colors==FALSE)){
		BYTE* r0=GetBits();
		for(long y=0;y<head.biHeight;y++){
			if (info.nEscape) longjmp(jerr.setjmp_buffer, 1); // <vho> - cancel decoding
			RGBtoBGR(r0,3*head.biWidth);
			r0+=info.dwEffWidth;
		}
	}

	/* Step 8: Release JPEG decompression object */
	/* This is an important step since it will release a good deal of memory. */
	jpeg_destroy_decompress(&cinfo);

	/* At this point you may want to check to see whether any corrupt-data
	* warnings occurred (test whether jerr.pub.num_warnings is nonzero).
	*/

	/* And we're done! */
	return true;
}
////////////////////////////////////////////////////////////////////////////////
#if CXIMAGE_SUPPORT_ENCODE
////////////////////////////////////////////////////////////////////////////////
bool CxImageJPG::Encode(CxFile * hFile)
{
	if (EncodeSafeCheck(hFile)) return false;

	if (head.biClrUsed!=0 && !IsGrayScale()){
		strcpy(info.szLastError,"JPEG can save only RGB or GreyScale images");
		return false;
	}	

	/* This struct contains the JPEG compression parameters and pointers to
	* working space (which is allocated as needed by the JPEG library).
	* It is possible to have several such structures, representing multiple
	* compression/decompression processes, in existence at once.  We refer
	* to any one struct (and its associated working data) as a "JPEG object".
	*/
	struct jpeg_compress_struct cinfo;
	/* This struct represents a JPEG error handler.  It is declared separately
	* because applications often want to supply a specialized error handler
	* (see the second half of this file for an example).  But here we just
	* take the easy way out and use the standard error handler, which will
	* print a message on stderr and call exit() if compression fails.
	* Note that this struct must live as long as the main JPEG parameter
	* struct, to avoid dangling-pointer problems.
	*/
	//struct jpeg_error_mgr jerr;
	/* We use our private extension JPEG error handler. <CSC> */
	struct ima_error_mgr jerr;
	jerr.buffer=info.szLastError;
	/* More stuff */
	int row_stride;		/* physical row width in image buffer */
	JSAMPARRAY buffer;		/* Output row buffer */

	/* Step 1: allocate and initialize JPEG compression object */
	/* We have to set up the error handler first, in case the initialization
	* step fails.  (Unlikely, but it could happen if you are out of memory.)
	* This routine fills in the contents of struct jerr, and returns jerr's
	* address which we place into the link field in cinfo.
	*/
	//cinfo.err = jpeg_std_error(&jerr); <CSC>
	/* We set up the normal JPEG error routines, then override error_exit. */
	cinfo.err = jpeg_std_error(&jerr.pub);
	jerr.pub.error_exit = ima_jpeg_error_exit;

	/* Establish the setjmp return context for my_error_exit to use. */
	if (setjmp(jerr.setjmp_buffer)) {
		/* If we get here, the JPEG code has signaled an error.
		* We need to clean up the JPEG object, close the input file, and return.
		*/
		strcpy(info.szLastError, jerr.buffer); //<CSC>
		jpeg_destroy_compress(&cinfo);
		return 0;
	}
	
	/* Now we can initialize the JPEG compression object. */
	jpeg_create_compress(&cinfo);
	/* Step 2: specify data destination (eg, a file) */
	/* Note: steps 2 and 3 can be done in either order. */
	/* Here we use the library-supplied code to send compressed data to a
	* stdio stream.  You can also write your own code to do something else.
	* VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
	* requires it in order to write binary files.
	*/

	//jpeg_stdio_dest(&cinfo, outfile);
	CxFileJpg dest(hFile);
    cinfo.dest = &dest;

	/* Step 3: set parameters for compression */
	/* First we supply a description of the input image.
	* Four fields of the cinfo struct must be filled in:
	*/
	cinfo.image_width = GetWidth(); 	// image width and height, in pixels
	cinfo.image_height = GetHeight();

	if (IsGrayScale()){
		cinfo.input_components = 1;			// # of color components per pixel
		cinfo.in_color_space = JCS_GRAYSCALE; /* colorspace of input image */
	} else {
		cinfo.input_components = 3; 	// # of color components per pixel
		cinfo.in_color_space = JCS_RGB; /* colorspace of input image */
	}

	/* Now use the library's routine to set default compression parameters.
	* (You must set at least cinfo.in_color_space before calling this,
	* since the defaults depend on the source color space.)
	*/
	jpeg_set_defaults(&cinfo);
	/* Now you can set any non-default parameters you wish to.
	* Here we just illustrate the use of quality (quantization table) scaling:
	*/
	//jpeg_set_quality(&cinfo, info.nQuality, TRUE /* limit to baseline-JPEG values */);
#ifdef C_ARITH_CODING_SUPPORTED
	if ((GetCodecOption() & ENCODE_ARITHMETIC) != 0)
		cinfo.arith_code = TRUE;
#endif
#ifdef ENTRPY_OPT_SUPPORTED
	if ((GetCodecOption() & ENCODE_OPTIMIZE) != 0)
		cinfo.optimize_coding = TRUE;
#endif
	if ((GetCodecOption() & ENCODE_GRAYSCALE) != 0)
		jpeg_set_colorspace(&cinfo, JCS_GRAYSCALE);
	if ((GetCodecOption() & ENCODE_SMOOTHING) != 0)
		cinfo.smoothing_factor = m_nSmoothing;
	jpeg_set_quality(&cinfo, GetJpegQuality(), (GetCodecOption() & ENCODE_BASELINE) != 0);
#ifdef C_PROGRESSIVE_SUPPORTED
	if ((GetCodecOption() & ENCODE_PROGRESSIVE) != 0)
		jpeg_simple_progression(&cinfo);
#endif
#ifdef C_LOSSLES_SUPPORTED
	if ((GetCodecOption() & ENCODE_LOSSLESS) != 0)
		jpeg_simple_lossless(&cinfo, m_nPredictor, m_nPointTransform);
#endif

	cinfo.density_unit=1;
	cinfo.X_density=(unsigned short)GetXDPI();
	cinfo.Y_density=(unsigned short)GetYDPI();

	/* Step 4: Start compressor */
	/* TRUE ensures that we will write a complete interchange-JPEG file.
	* Pass TRUE unless you are very sure of what you're doing.
	*/
	jpeg_start_compress(&cinfo, TRUE);

	/* Step 5: while (scan lines remain to be written) */
	/*           jpeg_write_scanlines(...); */
	/* Here we use the library's state variable cinfo.next_scanline as the
	* loop counter, so that we don't have to keep track ourselves.
	* To keep things simple, we pass one scanline per call; you can pass
	* more if you wish, though.
	*/
	row_stride = info.dwEffWidth;	/* JSAMPLEs per row in image_buffer */

	//<DP> "8+row_stride" fix heap deallocation problem during debug???
	buffer = (*cinfo.mem->alloc_sarray)
		((j_common_ptr) &cinfo, JPOOL_IMAGE, 8+row_stride, 1);

	CImageIterator iter(this);

	iter.Upset();
	while (cinfo.next_scanline < cinfo.image_height) {
		// info.nProgress = (long)(100*cinfo.next_scanline/cinfo.image_height);
		iter.GetRow(buffer[0], row_stride);
		// not necessary if swapped red and blue definition in jmorecfg.h;ln322 <W. Morrison>
		if (head.biClrUsed==0){				 // swap R & B for RGB images
			RGBtoBGR(buffer[0], row_stride); // Lance : 1998/09/01 : Bug ID: EXP-2.1.1-9
		}
		iter.PrevRow();
		(void) jpeg_write_scanlines(&cinfo, buffer, 1);
	}

	/* Step 6: Finish compression */
	jpeg_finish_compress(&cinfo);

	/* Step 7: release JPEG compression object */
	/* This is an important step since it will release a good deal of memory. */
	jpeg_destroy_compress(&cinfo);

	/* And we're done! */
	return true;
}
////////////////////////////////////////////////////////////////////////////////
#endif // CXIMAGE_SUPPORT_ENCODE
////////////////////////////////////////////////////////////////////////////////
#endif // CXIMAGE_SUPPORT_JPG