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

/*
 * File:	ximajpg.cpp
 * Purpose:	Platform Independent JPEG Image Class Loader and Writer
 * 07/Aug/2001 Davide Pizzolato - www.xdp.it
 * CxImage version 5.99a 08/Feb/2004
 */
 
#include "ximajpg.h"

#if CXIMAGE_SUPPORT_JPG

#include "ximaiter.h"
         
#include <setjmp.h>

struct ima_error_mgr {
	struct jpeg_error_mgr pub;	/* "public" fields */
	jmp_buf setjmp_buffer;		/* for return to caller */
	char* buffer;				/* error message <CSC>*/
};
typedef ima_error_mgr *ima_error_ptr;

////////////////////////////////////////////////////////////////////////////////
// Here's the routine that will replace the standard error_exit method:
////////////////////////////////////////////////////////////////////////////////
static void
ima_jpeg_error_exit (j_common_ptr cinfo)
{
	/* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
	ima_error_ptr myerr = (ima_error_ptr) cinfo->err;
	/* Create the message */
	myerr->pub.format_message (cinfo, myerr->buffer);
	/* Send it to stderr, adding a newline */
	/* Return control to the setjmp point */
	longjmp(myerr->setjmp_buffer, 1);
}
////////////////////////////////////////////////////////////////////////////////
CxImageJPG::CxImageJPG(): CxImage(CXIMAGE_FORMAT_JPG)
{
#if CXIMAGEJPG_SUPPORT_EXIF
	memset(&m_exifinfo, 0, sizeof(EXIFINFO));
#endif
}
////////////////////////////////////////////////////////////////////////////////
#if CXIMAGEJPG_SUPPORT_EXIF
bool CxImageJPG::DecodeExif(CxFile * hFile)
{
	long pos=hFile->Tell();
	CxExifInfo exif(&m_exifinfo);
	exif.DecodeExif(hFile);
	hFile->Seek(pos,SEEK_SET);
	return exif.m_exifinfo->IsExif;
}
#endif //CXIMAGEJPG_SUPPORT_EXIF
////////////////////////////////////////////////////////////////////////////////
bool CxImageJPG::Decode(CxFile * hFile)
{

	bool is_exif = false;
#if CXIMAGEJPG_SUPPORT_EXIF
	is_exif = DecodeExif(hFile);
#endif

	CImageIterator iter(this);
	/* This struct contains the JPEG decompression parameters and pointers to
	* working space (which is allocated as needed by the JPEG library).
	*/
	struct jpeg_decompress_struct cinfo;
	/* We use our private extension JPEG error handler. <CSC> */
	struct ima_error_mgr jerr;
	jerr.buffer=info.szLastError;
	/* More stuff */
	JSAMPARRAY buffer;	/* Output row buffer */
	int row_stride;		/* physical row width in output buffer */

	/* In this example we want to open the input file before doing anything else,
	* so that the setjmp() error recovery below can assume the file is open.
	* VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
	* requires it in order to read binary files.
	*/

	/* Step 1: allocate and initialize JPEG decompression object */
	/* 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.
		*/
		jpeg_destroy_decompress(&cinfo);
		return 0;
	}
	/* Now we can initialize the JPEG decompression object. */
	jpeg_create_decompress(&cinfo);

	/* Step 2: specify data source (eg, a file) */
	//jpeg_stdio_src(&cinfo, infile);
	CxFileJpg src(hFile);
    cinfo.src = &src;

	/* Step 3: read file parameters with jpeg_read_header() */
	(void) jpeg_read_header(&cinfo, TRUE);

	/* Step 4 <chupeev> handle decoder options*/
	if ((GetCodecOption() & DECODE_GRAYSCALE) != 0)
		cinfo.out_color_space = JCS_GRAYSCALE;
	if ((GetCodecOption() & DECODE_QUANTIZE) != 0) {
		cinfo.quantize_colors = TRUE;
		cinfo.desired_number_of_colors = info.nQuality;
	}
	if ((GetCodecOption() & DECODE_DITHER) != 0)
		cinfo.dither_mode = m_nDither;
	if ((GetCodecOption() & DECODE_ONEPASS) != 0)
		cinfo.two_pass_quantize = FALSE;
	if ((GetCodecOption() & DECODE_NOSMOOTH) != 0)
		cinfo.do_fancy_upsampling = FALSE;

//<DP>: Load true color images as RGB (no quantize) 
/* Step 4: set parameters for decompression */
/*  if (cinfo.jpeg_color_space!=JCS_GRAYSCALE) {
 *	cinfo.quantize_colors = TRUE;
 *	cinfo.desired_number_of_colors = 128;
 *}
 */ //</DP>

	// Set the scale <ignacio>
	cinfo.scale_denom = info.nScale;

	// Borrowed the idea from GIF implementation <ignacio>
	if (info.nEscape == -1) {
		// Return output dimensions only
		jpeg_calc_output_dimensions(&cinfo);
		head.biWidth = cinfo.output_width;
		head.biHeight = cinfo.output_height;
		jpeg_destroy_decompress(&cinfo);
		return true;
	}

	/* Step 5: Start decompressor */
	jpeg_start_decompress(&cinfo);

	/* We may need to do some setup of our own at this point before reading
	* the data.  After jpeg_start_decompress() we have the correct scaled
	* output image dimensions available, as well as the output colormap
	* if we asked for color quantization.
	*/
	//Create the image using output dimensions <ignacio>
	//Create(cinfo.image_width, cinfo.image_height, 8*cinfo.output_components, CXIMAGE_FORMAT_JPG);
	Create(cinfo.output_width, cinfo.output_height, 8*cinfo.output_components, CXIMAGE_FORMAT_JPG);

	if (!pDib) longjmp(jerr.setjmp_buffer, 1);  //<DP> check if the image has been created

	if (is_exif){
#if CXIMAGEJPG_SUPPORT_EXIF
	if ((m_exifinfo.Xresolution != 0.0) && (m_exifinfo.ResolutionUnit != 0))
		SetXDPI((long)(m_exifinfo.Xresolution/m_exifinfo.ResolutionUnit));
	if ((m_exifinfo.Yresolution != 0.0) && (m_exifinfo.ResolutionUnit != 0))
		SetYDPI((long)(m_exifinfo.Yresolution/m_exifinfo.ResolutionUnit));
#endif
	} else {
		if (cinfo.density_unit==2){
			SetXDPI((long)floor(cinfo.X_density * 254.0 / 10000.0 + 0.5));
			SetYDPI((long)floor(cinfo.Y_density * 254.0 / 10000.0 + 0.5));
		} else {
			SetXDPI(cinfo.X_density);
			SetYDPI(cinfo.Y_density);
		}
	}

	if (cinfo.out_color_space==JCS_GRAYSCALE){
		SetGrayPalette();
		head.biClrUsed =256;
	} else {
		if (cinfo.quantize_colors==TRUE){
			SetPalette(cinfo.actual_number_of_colors, cinfo.colormap[0], cinfo.colormap[1], cinfo.colormap[2]);
			head.biClrUsed=cinfo.actual_number_of_colors;
		} else {
			head.biClrUsed=0;
		}
	}

	/* JSAMPLEs per row in output buffer */
	row_stride = cinfo.output_width * cinfo.output_components;

	/* Make a one-row-high sample array that will go away when done with image */
	buffer = (*cinfo.mem->alloc_sarray)
		((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);

	/* Step 6: while (scan lines remain to be read) */
	/*           jpeg_read_scanlines(...); */
	/* Here we use the library's state variable cinfo.output_scanline as the
	* loop counter, so that we don't have to keep track ourselves.
	*/
	iter.Upset();
	while (cinfo.output_scanline < cinfo.output_height) {

		if (info.nEscape) longjmp(jerr.setjmp_buffer, 1); // <vho> - cancel decoding
		
		(void) jpeg_read_scanlines(&cinfo, buffer, 1);
		// info.nProgress = (long)(100*cinfo.output_scanline/cinfo.output_height);
		//<DP> Step 6a: CMYK->RGB */ 
		if ((cinfo.num_components==4)&&(cinfo.quantize_colors==FALSE)){
			BYTE k,*dst,*src;
			dst=iter.GetRow();
			src=buffer[0];
			for(long x3=0,x4=0; x3<(long)info.dwEffWidth && x4<row_stride; x3+=3, x4+=4){
				k=src[x4+3];