better jpeg autorot

jpeg write is more careful about removing exif tags that have been
removed from the image metadata

it failed previously if there were multiple Orientation tags

ChangeLog

@@ -23,6 +23,7 @@
 - @out_format in vips_system() can contain [options]
 - webpsave_buffer no longer ignores @lossless, thanks aaron42net
 - float tiff tagged as scRGB to match photoshop convention, thanks Murat
+- better jpeg autorot, thanks otto
 
 24/3/16 started 8.2.4
 - fix nohalo and vsqbs interpolators, thanks Rafael

libvips/conversion/autorot.c

@@ -33,6 +33,10 @@
 
  */
 
+/*
+#define DEBUG
+ */
+
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif /*HAVE_CONFIG_H*/
@@ -64,7 +68,7 @@ vips_autorot_get_angle_sub( VipsImage *image,
 	const char *orientation;
 
 	if( vips_isprefix( "exif-", field ) &&
-		vips_ispostfix( "-Orientation", field ) &&
+		vips_ispostfix( field, "-Orientation" ) &&
 		!vips_image_get_string( image, field, &orientation ) ) {
 		if( vips_isprefix( "6", orientation ) )
 			*angle = VIPS_ANGLE_D90;
@@ -82,6 +86,10 @@ vips_autorot_get_angle_sub( VipsImage *image,
 		 *
 		 * http://www.80sidea.com/archives/2316
 		 */
+
+		/* Stop searching.
+		 */
+		return( image ); 
 	}
 
 	return( NULL );
@@ -106,6 +114,10 @@ vips_autorot_get_angle( VipsImage *image )
 	angle = VIPS_ANGLE_D0;
 	(void) vips_image_map( image, vips_autorot_get_angle_sub, &angle );
 
+#ifdef DEBUG
+	printf( "vips_autorot_get_angle: %d\n", angle ); 
+#endif /*DEBUG*/
+
 	return( angle );
 }
 
@@ -114,8 +126,13 @@ vips_autorot_remove_angle_sub( VipsImage *image,
 	const char *field, GValue *value, void *my_data )
 {
 	if( vips_isprefix( "exif-", field ) &&
-		vips_ispostfix( "-Orientation", field ) )
+		vips_ispostfix( field, "-Orientation" ) ) {
+#ifdef DEBUG
+		printf( "vips_autorot_remove_angle: %s\n", field ); 
+#endif /*DEBUG*/
+
 		(void) vips_image_remove( image, field );
+	}
 
 	return( NULL );
 }
@@ -128,7 +145,7 @@ vips_autorot_remove_angle_sub( VipsImage *image,
  *
  * See also: vips_autorot_get_angle(). 
  */
-static void
+void
 vips_autorot_remove_angle( VipsImage *image )
 {
 	(void) vips_image_map( image, vips_autorot_remove_angle_sub, NULL );

libvips/foreign/vips2jpeg.c

@@ -49,7 +49,7 @@
  * 24/11/11
  * 	- turn into a set of write fns ready to be called from a class
  * 7/8/12
- * 	- use VIPS_META_RESOLUTION_UNIT to select resoltuion unit
+ * 	- use VIPS_META_RESOLUTION_UNIT to select resolution unit
  * 16/11/12
  * 	- read ifds from exif fields 
  * 	- optionally parse rationals as a/b
@@ -72,6 +72,8 @@
  * 	- set arbitrary exif tags from metadata
  * 25/11/15	
  * 	- don't write JFIF headers if we are stripping, thanks Benjamin
+ * 13/4/16
+ * 	- remove deleted exif fields more carefully
  */
 
 /*
@@ -626,12 +628,87 @@ vips_exif_image_field( VipsImage *image,
 	return( NULL ); 
 }
 
+typedef struct _VipsExif {
+	VipsImage *image;
+	ExifData *ed;
+	ExifContent *content;
+	GSList *to_remove;
+} VipsExif;
+
+static void
+vips_exif_exif_entry( ExifEntry *entry, VipsExif *ve )
+{
+	const char *tag_name;
+	char vips_name_txt[256];
+	VipsBuf vips_name = VIPS_BUF_STATIC( vips_name_txt );
+
+	if( !(tag_name = exif_tag_get_name( entry->tag )) )
+		return;
+
+	vips_buf_appendf( &vips_name, "exif-ifd%d-%s", 
+		exif_entry_get_ifd( entry ), tag_name );
+
+	/* Does this field exist on the image? If not, schedule it for
+	 * removal.
+	 */
+	if( !vips_image_get_typeof( ve->image, vips_buf_all( &vips_name ) ) ) 
+		ve->to_remove = g_slist_prepend( ve->to_remove, entry );
+}
+
+static void *
+vips_exif_exif_remove( ExifEntry *entry, VipsExif *ve )
+{
+#ifdef DEBUG
+{
+	const char *tag_name;
+	char vips_name_txt[256];
+	VipsBuf vips_name = VIPS_BUF_STATIC( vips_name_txt );
+
+	tag_name = exif_tag_get_name( entry->tag );
+	vips_buf_appendf( &vips_name, "exif-ifd%d-%s", 
+		exif_entry_get_ifd( entry ), tag_name );
+
+	printf( "vips_exif_exif_remove: %s\n", vips_buf_all( &vips_name ) );
+}
+#endif /*DEBUG*/
+
+	exif_content_remove_entry( ve->content, entry );
+
+	return( NULL );
+}
+
+static void
+vips_exif_exif_content( ExifContent *content, VipsExif *ve )
+{
+	ve->content = content;
+	ve->to_remove = NULL;
+        exif_content_foreach_entry( content, 
+		(ExifContentForeachEntryFunc) vips_exif_exif_entry, ve );
+	vips_slist_map2( ve->to_remove,
+		(VipsSListMap2Fn) vips_exif_exif_remove, ve, NULL );
+	VIPS_FREEF( g_slist_free, ve->to_remove );
+}
+
 static void
 vips_exif_update( ExifData *ed, VipsImage *image )
 {
+	VipsExif ve;
+
 	VIPS_DEBUG_MSG( "vips_exif_update: \n" );
 
+	/* Walk the image and update any stuff that's been changed in image
+	 * metadata.
+	 */
 	vips_image_map( image, vips_exif_image_field, ed );
+
+	/* Walk the exif and look for any fields which are NOT in image
+	 * metadata. They must have been removed ... remove them from exif as
+	 * well.
+	 */
+	ve.image = image;
+	ve.ed = ed;
+	exif_data_foreach_content( ed, 
+		(ExifDataForeachContentFunc) vips_exif_exif_content, &ve );
 }
 
 #endif /*HAVE_EXIF*/
@@ -667,9 +744,7 @@ write_blob( Write *write, const char *field, int app )
 #endif /*DEBUG*/
 
 			jpeg_write_marker( &write->cinfo, app, 
-				data, data_length );
-		}
-	}
+				data, data_length ); } }
 
 	return( 0 );
 }

libvips/include/vips/conversion.h

@@ -127,6 +127,7 @@ int vips_rot( VipsImage *in, VipsImage **out, VipsAngle angle, ... )
 int vips_rot45( VipsImage *in, VipsImage **out, ... )
 	__attribute__((sentinel));
 VipsAngle vips_autorot_get_angle( VipsImage *image );
+void vips_autorot_remove_angle( VipsImage *image );
 int vips_autorot( VipsImage *in, VipsImage **out, ... )
 	__attribute__((sentinel));
 int vips_zoom( VipsImage *in, VipsImage **out, int xfac, int yfac, ... )

tools/vipsthumbnail.c

@@ -93,8 +93,6 @@
 #include <vips/vips.h>
 #include <vips/internal.h>
 
-#define ORIENTATION ("exif-ifd0-Orientation")
-
 /* Default settings. We change the default to bicubic in main() if
  * this vips has been compiled with bicubic support.
  */
@@ -582,6 +580,9 @@ thumbnail_rotate( VipsObject *process, VipsImage *im )
 
 	if( rotate_image &&
 		angle != VIPS_ANGLE_D0 ) {
+		vips_info( "vipsthumbnail", "rotating by %s", 
+			vips_enum_nick( VIPS_TYPE_ANGLE, angle ) ); 
+
 		/* Need to copy to memory, we have to stay seq.
 		 */
 		t[0] = vips_image_new_memory();
@@ -590,7 +591,7 @@ thumbnail_rotate( VipsObject *process, VipsImage *im )
 			return( NULL ); 
 		im = t[1];
 
-		(void) vips_image_remove( im, ORIENTATION );
+		vips_autorot_remove_angle( im );
 	}
 
 	return( im );