update exif orientation on jpeg write

test the value of the 'exif-Orientation' tag and update exif on jpeg
write

ChangeLog

@@ -1,6 +1,7 @@
 12/10/11 started 7.26.6
 - NOCACHE was not being set correctly on OS X causing performance 
   problems with large files
+- update Orientation exif tag on jpeg write
 
 12/10/11 started 7.26.5
 - jpeg read/write copies over XMP data

libvips/format/im_jpeg2vips.c

@@ -271,9 +271,10 @@ attach_exif_entry( ExifEntry *entry, IMAGE *im )
 	vips_buf_init_static( &value, value_text, 256 );
 
 	vips_buf_appendf( &name, "exif-%s", exif_tag_get_title( entry->tag ) );
-	vips_buf_appendf( &value, "%s (%s, %d bytes)", 
+	vips_buf_appendf( &value, "%s (%s, %lu componets, %d bytes)", 
 		exif_entry_get_value( entry, exif_value, 256 ),
 		exif_format_get_name( entry->format ),
+		entry->components,
 		entry->size );
 
 	/* Can't do anything sensible with the error return.

libvips/format/im_vips2jpeg.c

@@ -42,6 +42,8 @@
  * 	- oop CMYK write was not inverting, thanks Ole
  * 12/10/2011
  * 	- write XMP data
+ * 18/10/2011
+ * 	- update Orientation as well
  */
 
 /*
@@ -72,8 +74,8 @@
 
 /*
 #define DEBUG_VERBOSE
-#define DEBUG
  */
+#define DEBUG
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>
@@ -314,10 +316,16 @@ write_tag( ExifData *ed, ExifTag tag, ExifFormat f, write_fn fn, void *data )
 		ExifEntry *entry;
 
 		entry = exif_entry_new();
+
+		/* tag must be set before calling exif_content_add_entry.
+		 */
+		entry->tag = tag; 
+
 		exif_content_add_entry( ed->ifd[0], entry );
 		exif_entry_initialize( entry, tag );
-		fn( entry, bo, data );
 		exif_entry_unref( entry );
+
+		fn( entry, bo, data );
 	}
 
 	return( 0 );
@@ -356,6 +364,62 @@ set_exif_resolution( ExifData *ed, IMAGE *im )
 
 	return( 0 );
 }
+
+static void *
+update_orientation_cb( VipsImage *in, const char *name, GValue *value, void *a )
+{
+	/* Sadly these strings are subject to i18n by libexif. We should
+	 * attach EXIF data as binary and leave interpretaion to the UI argh.
+	 */
+	static const char *orientations[] = {
+		"", 
+		"Top-left", "Top-right", "Bottom-right",
+		"Bottom-left", "Left-top", "Right-top",
+		"Right-bottom", "Left-bottom", 
+		NULL
+	};
+
+	ExifData *ed = (ExifData *) a;
+
+	int i;
+	ExifShort orientation;
+
+	if( vips_isprefix( "exif-Orientation", name ) ) {
+		const char *string;
+
+		if( !(string = vips_ref_string_get( value )) ) {
+			vips_warn( "im_jpeg2vips", 
+				"%s", _( "exif-Orientation is not a string" ) );
+			return( NULL );
+		}
+
+		orientation = 0;
+		for( i = 0; orientations[i]; i++ ) 
+			if( strlen( orientations[i] ) > 0 &&
+				vips_isprefix( orientations[i], string ) ) {
+				orientation = i;
+				break;
+			}
+		if( orientation == 0 ) {
+			vips_warn( "im_jpeg2vips", 
+				"%s", _( "unknown JPEG orientation" ) );
+			return( NULL );
+		}
+
+		if( write_tag( ed, EXIF_TAG_ORIENTATION, EXIF_FORMAT_SHORT,
+			write_short, &orientation ) ) {
+			vips_warn( "im_jpeg2vips", 
+				"%s", _( "error setting JPEG orientation" ) );
+			return( NULL );
+		}
+
+#ifdef DEBUG
+		printf( "im_vips2jpeg: updated orientation\n" );
+#endif /*DEBUG*/
+	}
+
+	return( NULL );
+}
 #endif /*HAVE_EXIF*/
 
 static int
@@ -378,9 +442,23 @@ write_exif( Write *write )
 		if( !(ed = exif_data_new_from_data( data, data_length )) )
 			return( -1 );
 	}
-	else 
+	else  {
 		ed = exif_data_new();
 
+		exif_data_set_option( ed, 
+			EXIF_DATA_OPTION_FOLLOW_SPECIFICATION );
+		exif_data_set_data_type( ed, EXIF_DATA_TYPE_COMPRESSED );
+		exif_data_set_byte_order( ed, EXIF_BYTE_ORDER_INTEL );
+	
+		/* Create the mandatory EXIF fields with default data.
+		 */
+		exif_data_fix( ed );
+	}
+
+	/* Update EXIF orientation from VIPS.
+	 */
+	(void) vips_image_map( write->in, update_orientation_cb, ed );
+
 	/* Update EXIF resolution from VIPS.
 	 */
 	if( set_exif_resolution( ed, write->in ) ) {

libvips/iofuncs/header.c

@@ -112,7 +112,7 @@
  * Various convenience functions (eg. vips_image_set_int()) let you easily 
  * attach 
  * simple types like
- * numbers, strings and memory blocks to images. Use vips_header_map() to loop
+ * numbers, strings and memory blocks to images. Use vips_image_map() to loop
  * over an image's fields, including all metadata.
  *
  * Items of metadata are identified by strings. Some strings are reserved, for
@@ -479,8 +479,6 @@ vips_image_init_fields( VipsImage *image,
 static void *
 meta_cp_field( VipsMeta *meta, VipsImage *dst )
 {
-	VipsMeta *meta_copy;
-
 #ifdef DEBUG
 {
 	char *str_value;
@@ -494,7 +492,7 @@ meta_cp_field( VipsMeta *meta, VipsImage *dst )
 
 	/* No way to return error here, sadly.
 	 */
-	meta_copy = meta_new( dst, meta->field, &meta->value );
+	(void) meta_new( dst, meta->field, &meta->value );
 
 #ifdef DEBUG
 	meta_sanity( dst );