setting EXIF data blocks sets other tags too

calling vips_image_set() to set the EXIF data block VIPS_META_EXIF_NAME
will automaticaly set other tags, like orientation etc.

ChangeLog

@@ -40,6 +40,7 @@
 - add gif-delay, gif-comment and gif-loop metadata
 - add dispose handling to gifload
 - deprecate the "centre" option for vips_resize(): it's now always on
+- setting the EXIF data block automatically sets other image tags
 
 29/8/17 started 8.5.9
 - make --fail stop jpeg read on any libjpeg warning, thanks @mceachen

libvips/foreign/exif.c

@@ -484,7 +484,7 @@ vips__exif_parse( VipsImage *image )
 		return( -1 ); 
 	}
 
-	/* Make sure all required fields are there before we attach to vips
+	/* Make sure all required fields are there before we attach the vips
 	 * metadata.
 	 */
 	exif_data_fix( ed );

libvips/foreign/jpeg2vips.c

@@ -514,9 +514,6 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
 			(VipsCallbackFn) vips_free, data, data_length );
 	}
 
-	if( vips__exif_parse( out ) )
-		return( -1 );
-
 	/* Tell downstream we are reading sequentially.
 	 */
 	vips_image_set_area( out, VIPS_META_SEQUENTIAL, NULL, NULL ); 

libvips/foreign/pforeign.h

@@ -239,9 +239,6 @@ int vips__openslide_read( const char *filename, VipsImage *out,
 int vips__openslide_read_associated( const char *filename, VipsImage *out, 
 	const char *associated );
 
-int vips__exif_parse( VipsImage *image );
-int vips__exif_update( VipsImage *image );
-
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/

libvips/foreign/vips2webp.c

@@ -53,6 +53,7 @@
 #include <string.h>
 
 #include <vips/vips.h>
+#include <vips/internal.h>
 
 #include "pforeign.h"
 

libvips/foreign/webp2vips.c

@@ -269,11 +269,6 @@ read_header( Read *read, VipsImage *out )
 	}
 
 	WebPMuxDelete( mux ); 
-
-	/* We may have read some exif ... parse into the header.
-	 */
-	if( vips__exif_parse( out ) )
-		return( -1 ); 
 }
 #endif /*HAVE_LIBWEBPMUX*/
 

libvips/include/vips/internal.h

@@ -52,6 +52,9 @@ typedef struct _VipsMeta {
 	GValue value;			/* copy of value */
 } VipsMeta;
 
+int vips__exif_parse( VipsImage *image );
+int vips__exif_update( VipsImage *image );
+
 void vips_check_init( void );
 
 void vips__meta_init_types( void );

libvips/iofuncs/header.c

@@ -962,6 +962,16 @@ vips_image_set( VipsImage *image, const char *name, GValue *value )
 	meta_init( image );
 	(void) meta_new( image, name, value );
 
+	/* If we're setting an EXIF data block, we need to automatically expand 
+	 * out all the tags. This will set things like xres/yres too.
+	 *
+	 * We do this herfe rather than in meta_new() since we don't want to
+	 * trigger on copy_fields.
+	 */
+	if( strcmp( name, VIPS_META_EXIF_NAME ) == 0 ) 
+		if( vips__exif_parse( image ) ) 
+			g_warning( "image_set: bad exif data" );
+
 #ifdef DEBUG
 	meta_sanity( image );
 #endif /*DEBUG*/