[gthumb: 77/129] jpeg_utils: added function to read image width and height from the jpeg header

[Paolo Bacchilega <paobac src gnome org>]

commit 001de4a94d2c026dc7a233087b1df036d89ca42b
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Mon Apr 25 15:21:56 2011 +0200

    jpeg_utils: added function to read image width and height from the jpeg header

 extensions/jpeg_utils/Makefile.am             |    4 +-
 extensions/jpeg_utils/jpeg-exif-orientation.c |  189 ------------
 extensions/jpeg_utils/jpeg-exif-orientation.h |   30 --
 extensions/jpeg_utils/jpeg-info.c             |  407 +++++++++++++++++++++++++
 extensions/jpeg_utils/jpeg-info.h             |   41 +++
 5 files changed, 450 insertions(+), 221 deletions(-)
---
diff --git a/extensions/jpeg_utils/Makefile.am b/extensions/jpeg_utils/Makefile.am
index 5efee06..349d720 100644
--- a/extensions/jpeg_utils/Makefile.am
+++ b/extensions/jpeg_utils/Makefile.am
@@ -7,8 +7,8 @@ libjpeg_utils_la_SOURCES = 		\
 	jmemorydest.h			\
 	jmemorysrc.c			\
 	jmemorysrc.h			\
-	jpeg-exif-orientation.c		\
-	jpeg-exif-orientation.h		\
+	jpeg-info.c			\
+	jpeg-info.h			\
 	jpegtran.c			\
 	jpegtran.h			\
 	transupp.h			\
diff --git a/extensions/jpeg_utils/jpeg-info.c b/extensions/jpeg_utils/jpeg-info.c
new file mode 100644
index 0000000..a225382
--- /dev/null
+++ b/extensions/jpeg_utils/jpeg-info.c
@@ -0,0 +1,407 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+
+/*
+ *  GThumb
+ *
+ *  Copyright (C) 2011 Free Software Foundation, Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include <config.h>
+#include "jpeg-info.h"
+
+
+static guchar
+_jpeg_read_segment_marker (GDataInputStream  *data_stream,
+			   GCancellable      *cancellable,
+			   GError           **error)
+{
+	guchar marker_id;
+
+	while ((marker_id = g_data_input_stream_read_byte (data_stream, cancellable, error)) == 0xff)
+		/* skip padding */;
+
+	return marker_id;
+}
+
+
+static gboolean
+_jpeg_skip_segment_data (GDataInputStream  *data_stream,
+			 guchar             marker_id,
+			 GCancellable      *cancellable,
+			 GError           **error)
+{
+	if (marker_id == 0xd9)  /* EOI => end of image */
+		return FALSE;
+	if (marker_id == 0xda)  /* SOS => end of header */
+		return FALSE;
+
+	if ((marker_id != 0xd0)
+	    && (marker_id != 0xd1)
+	    && (marker_id != 0xd2)
+	    && (marker_id != 0xd3)
+	    && (marker_id != 0xd4)
+	    && (marker_id != 0xd5)
+	    && (marker_id != 0xd6)
+	    && (marker_id != 0xd7)
+	    && (marker_id != 0xd8)
+	    && (marker_id != 0x01))
+	{
+		guint h, l;
+		guint segment_size;
+
+		/* skip to the next segment */
+
+		h = g_data_input_stream_read_byte (data_stream, cancellable, error);
+		l = g_data_input_stream_read_byte (data_stream, cancellable, error);
+		segment_size = (h << 8) + l;
+
+		if (g_input_stream_skip (G_INPUT_STREAM (data_stream),
+					 segment_size - 2,
+					 cancellable,
+					 error) < 0)
+		{
+			return FALSE;
+		}
+	}
+
+	return TRUE;
+}
+
+
+static gboolean
+_jpeg_skip_to_segment (GDataInputStream  *data_stream,
+		       guchar             segment_id,
+		       GCancellable      *cancellable,
+		       GError           **error)
+{
+	guchar marker_id = 0x00;
+
+	while ((marker_id = _jpeg_read_segment_marker (data_stream, cancellable, error)) != 0x00) {
+		if (marker_id == segment_id)
+			return TRUE;
+		if (! _jpeg_skip_segment_data (data_stream, marker_id, cancellable, error))
+			return FALSE;
+	}
+
+	return FALSE;
+}
+
+
+static GthTransform
+_jpeg_exif_orientation_from_app1_segment (guchar *in_buffer,
+					  gsize   app1_segment_size)
+{
+	int       pos;
+	guint     length;
+	gboolean  is_motorola;
+	guchar   *exif_data;
+	guint     offset, number_of_tags, tagnum;
+	int       orientation;
+
+	/* Length includes itself, so must be at least 2 */
+	/* Following Exif data length must be at least 6 */
+
+	length = app1_segment_size;
+	if (length < 8)
+		return 0;
+
+	pos = 0;
+
+	/* Read Exif head, check for "Exif" */
+
+	if ((in_buffer[pos++] != 0x45)
+	    || (in_buffer[pos++] != 0x78)
+	    || (in_buffer[pos++] != 0x69)
+	    || (in_buffer[pos++] != 0x66)
+	    || (in_buffer[pos++] != 0)
+	    || (in_buffer[pos++] != 0))
+	{
+		return 0;
+	}
+
+	/* Length of an IFD entry */
+
+	if (length < 12)
+		return 0;
+
+	exif_data = in_buffer + pos;
+
+	/* Discover byte order */
+
+	if ((exif_data[0] == 0x49) && (exif_data[1] == 0x49))
+		is_motorola = FALSE;
+	else if ((exif_data[0] == 0x4D) && (exif_data[1] == 0x4D))
+		is_motorola = TRUE;
+	else
+		return 0;
+
+	/* Check Tag Mark */
+
+	if (is_motorola) {
+		if (exif_data[2] != 0)
+			return 0;
+		if (exif_data[3] != 0x2A)
+			return 0;
+	}
+	else {
+		if (exif_data[3] != 0)
+			return 0;
+		if (exif_data[2] != 0x2A)
+			return 0;
+	}
+
+	/* Get first IFD offset (offset to IFD0) */
+
+	if (is_motorola) {
+		if (exif_data[4] != 0)
+			return 0;
+		if (exif_data[5] != 0)
+			return 0;
+		offset = exif_data[6];
+		offset <<= 8;
+		offset += exif_data[7];
+	}
+	else {
+		if (exif_data[7] != 0)
+			return 0;
+		if (exif_data[6] != 0)
+			return 0;
+		offset = exif_data[5];
+		offset <<= 8;
+		offset += exif_data[4];
+	}
+
+	if (offset > length - 2) /* check end of data segment */
+		return 0;
+
+	/* Get the number of directory entries contained in this IFD */
+
+	if (is_motorola) {
+		number_of_tags = exif_data[offset];
+		number_of_tags <<= 8;
+		number_of_tags += exif_data[offset+1];
+	}
+	else {
+		number_of_tags = exif_data[offset+1];
+		number_of_tags <<= 8;
+		number_of_tags += exif_data[offset];
+	}
+	if (number_of_tags == 0)
+		return 0;
+
+	offset += 2;
+
+	/* Search for Orientation Tag in IFD0 */
+
+	for (;;) {
+		if (offset > length - 12) /* check end of data segment */
+			return 0;
+
+		/* Get Tag number */
+
+		if (is_motorola) {
+			tagnum = exif_data[offset];
+			tagnum <<= 8;
+			tagnum += exif_data[offset+1];
+		}
+		else {
+			tagnum = exif_data[offset+1];
+			tagnum <<= 8;
+			tagnum += exif_data[offset];
+		}
+
+		if (tagnum == 0x0112) /* found Orientation Tag */
+			break;
+
+		if (--number_of_tags == 0)
+			return 0;
+
+		offset += 12;
+	}
+
+	/* Get the Orientation value */
+
+	if (is_motorola) {
+		if (exif_data[offset + 8] != 0)
+			return 0;
+		orientation = exif_data[offset + 9];
+	}
+	else {
+		if (exif_data[offset + 9] != 0)
+			return 0;
+		orientation = exif_data[offset + 8];
+	}
+
+	if (orientation > 8)
+		orientation = 0;
+
+	return (GthTransform) orientation;
+}
+
+
+gboolean
+_jpeg_get_image_info (GInputStream  *stream,
+		      int           *width,
+		      int           *height,
+		      GthTransform  *orientation,
+		      GCancellable  *cancellable,
+		      GError       **error)
+{
+	gboolean          size_read;
+	gboolean          orientation_read;
+	GDataInputStream *data_stream;
+	guchar            marker_id;
+
+	size_read = FALSE;
+
+	if (orientation != NULL) {
+		*orientation = GTH_TRANSFORM_NONE;
+		orientation_read = FALSE;
+	}
+	else
+		/* no need to search for the orientation flag if orientation is NULL */
+		orientation_read = TRUE;
+
+	data_stream = g_data_input_stream_new (stream);
+	g_filter_input_stream_set_close_base_stream (G_FILTER_INPUT_STREAM (data_stream), FALSE);
+
+	while ((marker_id = _jpeg_read_segment_marker (data_stream, cancellable, error)) != 0x00) {
+		if (marker_id == 0xc0) { /* SOF0 */
+			guint h, l;
+			guint size;
+
+			/* size */
+
+			h = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			l = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			size = (h << 8) + l;
+
+			/* data precision */
+
+			(void) g_data_input_stream_read_byte (data_stream, cancellable, error);
+
+			/* height */
+
+			h = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			l = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			if (height != NULL)
+				*height = (h << 8) + l;
+
+			/* width */
+
+			h = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			l = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			if (width != NULL)
+				*width = (h << 8) + l;
+
+			size_read = TRUE;
+
+			/* skip to the end of the segment */
+
+			if (! orientation_read)
+				g_input_stream_skip (G_INPUT_STREAM (data_stream), size - 7, cancellable, error);
+		}
+
+		if (! orientation_read && (marker_id == 0xe1)) { /* APP1 */
+			guint   h, l;
+			gsize   size;
+			guchar *app1_segment;
+
+			/* size */
+
+			h = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			l = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			size = (h << 8) + l;
+
+			app1_segment = g_new (guchar, size);
+			if (g_input_stream_read (stream, app1_segment, size, cancellable, error) > 0)
+				*orientation = _jpeg_exif_orientation_from_app1_segment (app1_segment, size);
+
+			orientation_read = TRUE;
+
+			g_free (app1_segment);
+		}
+
+		if (size_read && orientation_read)
+			break;
+
+		if (! _jpeg_skip_segment_data (data_stream, marker_id, cancellable, error))
+			break;
+	}
+
+	g_object_unref (data_stream);
+
+	return size_read;
+}
+
+
+GthTransform
+_jpeg_exif_orientation (guchar *in_buffer,
+			gsize   in_buffer_size)
+{
+	GInputStream *stream;
+	GthTransform  orientation;
+
+	stream = g_memory_input_stream_new_from_data (in_buffer, in_buffer_size, NULL);
+	orientation = _jpeg_exif_orientation_from_stream (stream, NULL, NULL);
+
+	g_object_unref (stream);
+
+	return orientation;
+}
+
+
+GthTransform
+_jpeg_exif_orientation_from_stream (GInputStream  *stream,
+				    GCancellable  *cancellable,
+				    GError       **error)
+{
+	GthTransform      orientation;
+	GDataInputStream *data_stream;
+
+	orientation = GTH_TRANSFORM_NONE;
+	data_stream = g_data_input_stream_new (stream);
+	g_filter_input_stream_set_close_base_stream (G_FILTER_INPUT_STREAM (data_stream), FALSE);
+
+	if (_jpeg_read_segment_marker (data_stream, cancellable, error) == 0xd8) {
+		if (_jpeg_skip_to_segment (data_stream, 0xe1, cancellable, error)) {
+			guint   h, l;
+			guint   app1_segment_size;
+			guchar *app1_segment;
+
+			h = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			l = g_data_input_stream_read_byte (data_stream, cancellable, error);
+			app1_segment_size = (h << 8) + l;
+
+			app1_segment = g_new (guchar, app1_segment_size);
+			if (g_input_stream_read (stream,
+						 app1_segment,
+						 app1_segment_size,
+						 cancellable,
+						 error) > 0)
+			{
+				orientation = _jpeg_exif_orientation_from_app1_segment (app1_segment, app1_segment_size);
+			}
+
+			g_free (app1_segment);
+		}
+	}
+
+	g_object_unref (data_stream);
+
+	return orientation;
+}
diff --git a/extensions/jpeg_utils/jpeg-info.h b/extensions/jpeg_utils/jpeg-info.h
new file mode 100644
index 0000000..4807fa3
--- /dev/null
+++ b/extensions/jpeg_utils/jpeg-info.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
+
+/*
+ *  GThumb
+ *
+ *  Copyright (C) 2001-2009 The Free Software Foundation, Inc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef JPEG_INFO_H
+#define JPEG_INFO_H
+
+#include <gthumb.h>
+
+#define JPEG_SEGMENT_MAX_SIZE (64 * 1024)
+
+gboolean      _jpeg_get_image_info                     (GInputStream      *stream,
+		      	      	      	       	        int               *width,
+		      	      	      	       	        int               *height,
+		      	      	      	       	        GthTransform      *orientation,
+		      	      	      	       	        GCancellable      *cancellable,
+		      	      	      	       	        GError           **error);
+GthTransform  _jpeg_exif_orientation                   (guchar            *in_buffer,
+				      	      	        gsize              in_buffer_size);
+GthTransform  _jpeg_exif_orientation_from_stream       (GInputStream      *stream,
+				    	    	        GCancellable      *cancellable,
+				    	    	        GError           **error);
+
+#endif /* JPEG_INFO_H */