format_canon.c

Gqview,Linux下基于GTK+库写成的轻量级而能丰富的图像浏览程序。

/*
 *  GQView
 *  (C) 2005 John Ellis
 *
 * This software is released under the GNU General Public License (GNU GPL).
 * Please read the included file COPYING for more information.
 * This software comes with no warranty of any kind, use at your own risk!
 *
 *
 * Code to add support for Canon CR2 and CRW files, version 0.2
 *
 * Developed by Daniel M. German, dmgerman at uvic.ca 
 *
 * you can find the sources for this patch at http://turingmachine.org/~dmg/libdcraw/gqview/
 *
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif


#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <glib.h>

#include "intl.h"

#include "format_canon.h"
#include "format_raw.h"

#include "exif.h"


/*
 *-----------------------------------------------------------------------------
 * Raw (CR2, CRW) embedded jpeg extraction for Canon
 *-----------------------------------------------------------------------------
 */

static gint canon_cr2_tiff_entry(unsigned char *data, const guint len, guint offset, ExifByteOrder bo,
				 guint *image_offset, gint *jpeg_encoding)
{
	guint tag;
	guint type;
	guint count;
	guint jpeg_start;

	/* the two (tiff compliant) tags we want are:
	 *  0x0103 image compression type (must be type 6 for jpeg)
	 *  0x0111 jpeg start offset
	 * only use the first segment that contains an actual jpeg - as there
	 * is a another that contains the raw data.
	 */
	tag = exif_byte_get_int16(data + offset + EXIF_TIFD_OFFSET_TAG, bo);
	type = exif_byte_get_int16(data + offset + EXIF_TIFD_OFFSET_FORMAT, bo);
	count = exif_byte_get_int32(data + offset + EXIF_TIFD_OFFSET_COUNT, bo);

	/* tag 0x0103 contains the compression type for this segment's image data */
	if (tag == 0x0103)
		{
		if (ExifFormatList[type].size * count == 2 &&
		    exif_byte_get_int16(data + offset + EXIF_TIFD_OFFSET_DATA, bo) == 6)
			{
			*jpeg_encoding = TRUE;
			}
		return FALSE;
		}

	/* find and verify jpeg offset */
	if (tag != 0x0111 ||
	    !jpeg_encoding) return FALSE;

	/* make sure data segment contains 4 bytes */
	if (ExifFormatList[type].size * count != 4) return FALSE;

	jpeg_start = exif_byte_get_int32(data + offset + EXIF_TIFD_OFFSET_DATA, bo);

	/* verify this is jpeg data */
	if (len < jpeg_start + 4 ||
	    memcmp(data + jpeg_start, "\xff\xd8", 2) != 0)
		{
		return FALSE;
		}

	*image_offset = jpeg_start;
	return TRUE;
}

static gint canon_cr2_tiff_table(unsigned char *data, const guint len, guint offset, ExifByteOrder bo,
				 guint *image_offset)
{
	gint jpeg_encoding = FALSE;
	guint count;
	guint i;

	if (len < offset + 2) return 0;

	count = exif_byte_get_int16(data + offset, bo);
	offset += 2;
	if (len < offset + count * EXIF_TIFD_SIZE + 4) return 0;

	for (i = 0; i < count; i++)
		{
		if (canon_cr2_tiff_entry(data, len, offset + i * EXIF_TIFD_SIZE, bo,
					 image_offset, &jpeg_encoding))
			{
			return 0;
			}
		}

	return exif_byte_get_int32(data + offset + count * EXIF_TIFD_SIZE, bo);
}

gint format_canon_raw_cr2(unsigned char *data, const guint len,
			  guint *image_offset, guint *exif_offset)
{
	guint jpeg_offset = 0;
	ExifByteOrder bo;
	guint offset;
	gint level;

	/* cr2 files are tiff files with a few canon specific directory tags
	 * they are (always ?) in little endian format
	 */
	if (!exif_tiff_directory_offset(data, len, &offset, &bo)) return FALSE;

	level = 0;
	while (offset && level < EXIF_TIFF_MAX_LEVELS)
		{
		offset = canon_cr2_tiff_table(data, len, offset, bo, &jpeg_offset);
		level++;

		if (jpeg_offset != 0)
			{
			if (image_offset) *image_offset = jpeg_offset;
			return TRUE;
			}
		}

	return FALSE;
}

#define CRW_BYTE_ORDER		EXIF_BYTE_ORDER_INTEL
#define CRW_HEADER_SIZE		26
#define CRW_DIR_ENTRY_SIZE	10

gint format_canon_raw_crw(unsigned char *data, const guint len,
			  guint *image_offset, guint *exif_offset)
{
	guint block_offset;
	guint data_length;
	guint offset;
	guint count;
	guint i;

	/* CRW header starts with 2 bytes for byte order (always "II", little endian),
	 * 4 bytes for start of root block,
	 * and 8 bytes of magic for file type and format "HEAPCCDR"
	 * (also 4 bytes for file version, and 8 bytes reserved)
	 *
	 * CIFF specification in pdf format is available on some websites,
	 * search for "CIFFspecV1R03.pdf" or "CIFFspecV1R04.pdf"
	 */
	if (len < CRW_HEADER_SIZE ||
	    memcmp(data, "II", 2) != 0 ||
	    memcmp(data + 6, "HEAPCCDR", 8) != 0)
		{
		return FALSE;
		}

	block_offset = exif_byte_get_int32(data + 2, CRW_BYTE_ORDER);

	/* the end of the root block equals end of file,
	 * the last 4 bytes of the root block contain the block's data size
	 */
	offset = len - 4;
	data_length = exif_byte_get_int32(data + offset, CRW_BYTE_ORDER);

	offset = block_offset + data_length;
	if (len < offset + 2) return FALSE;

	/* number of directory entries for this block is in
	 * the next two bytes after the data for this block.
	 */
	count = exif_byte_get_int16(data + offset, CRW_BYTE_ORDER);
	offset += 2;
	if (len < offset + count * CRW_DIR_ENTRY_SIZE + 4) return FALSE;

	/* walk the directory entries looking for type jpeg (tag 0x2007),
	 * for reference, other tags are 0x2005 for raw and 0x300a for photo info:
	 */
	for (i = 0; i < count ; i++)
		{
		guint entry_offset;
		guint record_type;
		guint record_offset;
		guint record_length;

		entry_offset = offset + i * CRW_DIR_ENTRY_SIZE;

		/* entry is 10 bytes (in order):
		 *  2 for type
		 *  4 for length of data
		 *  4 for offset into data segment of this block
		 */
		record_type = exif_byte_get_int16(data + entry_offset, CRW_BYTE_ORDER);
		record_length = exif_byte_get_int32(data + entry_offset + 2, CRW_BYTE_ORDER);
		record_offset = exif_byte_get_int32(data + entry_offset + 6, CRW_BYTE_ORDER);

		/* tag we want for jpeg data */
		if (record_type == 0x2007)
			{
			guint jpeg_offset;

			jpeg_offset = block_offset + record_offset;
		 	if (len < jpeg_offset + record_length ||
			    record_length < 4 ||
			    memcmp(data + jpeg_offset, "\xff\xd8\xff\xdb", 4) != 0)
				{
				return FALSE;
				}

			/* we now know offset and verified jpeg */
			*image_offset = jpeg_offset;
			return TRUE;
			}
		}

	return FALSE;
}


/*
 *-----------------------------------------------------------------------------
 * EXIF Makernote for Canon
 *-----------------------------------------------------------------------------
 */

static ExifTextList CanonSet1MacroMode[] = {
	{ 1,	"macro" },
	{ 2,	"normal" },
	EXIF_TEXT_LIST_END
};

static ExifTextList CanonSet1Quality[] = {
	{ 2,	"normal" },
	{ 3,	"fine" },
	{ 4,	"raw" },
	{ 5,	"superfine" },
	EXIF_TEXT_LIST_END
};

static ExifTextList CanonSet1FlashMode[] = {
	{ 0,	"flash not fired" },
	{ 1,	"auto" },
	{ 2,	"on" },
	{ 3,	"red-eye reduction" },
	{ 4,	"slow sync" },
	{ 5,	"auto + red-eye reduction" },
	{ 6,	"on + red-eye reduction" },
	{ 16,	"external flash" },
	EXIF_TEXT_LIST_END
};

static ExifTextList CanonSet1DriveMode[] = {
	{ 0,	"single or timer" },
	{ 1,	"continuous" },
	EXIF_TEXT_LIST_END
};

static ExifTextList CanonSet1FocusMode[] = {
	{ 0,	"one-shot AF" },
	{ 1,	"AI servo AF" },
	{ 2,	"AI focus AF" },
	{ 3,	"manual" },
	{ 4,	"single" },
	{ 5,	"continuous" },
	{ 6,	"manual" },
	EXIF_TEXT_LIST_END
};

static ExifTextList CanonSet1ImageSize[] = {
	{ 0,	"large" },
	{ 1,	"medium" },
	{ 2,	"small" },
	/* where (or) does Medium 1/2 fit in here ? */
	EXIF_TEXT_LIST_END
};

static ExifTextList CanonSet1ShootingMode[] = {
	{ 0,	"auto" },
	{ 1,	"manual" },
	{ 2,	"landscape" },
	{ 3,	"fast shutter" },
	{ 4,	"slow shutter" },
	{ 5,	"night" },
	{ 6,	"black and white" },
	{ 7,	"sepia" },
	{ 8,	"portrait" },
	{ 9,	"sports" },
	{ 10,	"macro" },
	{ 11,	"pan focus" },
	EXIF_TEXT_LIST_END
};

/* Don't think this is interpreted correctly/completely, A60 at 2.5x Digital sets value of 3 */
static ExifTextList CanonSet1DigitalZoom[] = {
	{ 0,	"none" },
	{ 1,	"2x" },
	{ 2,	"4x" },
	{ 3,	"other" },
	EXIF_TEXT_LIST_END
};