getting closer ...

fix RefString handling, add a test case

TODO

@@ -1,3 +1,18 @@
+- try:
+
+>>> from gi.repository import Vips
+>>> x = Vips.Image.new_from_file("images/IMG_4618.jpg")
+>>> x.get_value("exif-ifd0-Orientation")
+'1 (Top-left, Short, 1 components, 2 bytes)'
+>>> x.set_value("exif-ifd0-Orientation", "2")
+>>> x.write_to_file("x.jpg")
+
+  Orientation comes out as zero in vipsheader -a x.jpg
+
+  add a test-case for changing exif from py
+
+
+
 - colour needs to split _build() into preprocess / process / postprocess
   phases
 

libvips/include/vips/type.h

@@ -140,6 +140,7 @@ typedef struct _VipsRefString {
 	VipsArea area;
 } VipsRefString;
 
+VipsRefString *vips_ref_string_new( const char *str );
 const char *vips_ref_string_get( VipsRefString *refstr, size_t *length );
 GType vips_ref_string_get_type( void );
 

libvips/iofuncs/header.c

@@ -1106,18 +1106,22 @@ static int
 meta_get_value( const VipsImage *image,
 	const char *field, GType type, GValue *value_copy )
 {
-	if( vips_image_get( image, field, value_copy ) )
+	GValue value = { 0 }; 
+
+	if( vips_image_get( image, field, &value ) )
 		return( -1 );
-	if( G_VALUE_TYPE( value_copy ) != type ) {
+	g_value_init( value_copy, type );
+	if( !g_value_transform( &value, value_copy ) ) { 
 		vips_error( "VipsImage",
 			_( "field \"%s\" is of type %s, not %s" ),
 			field,
 			g_type_name( G_VALUE_TYPE( value_copy ) ),
 			g_type_name( type ) );
-		g_value_unset( value_copy );
+		g_value_unset( &value );
 
 		return( -1 );
 	}
+	g_value_unset( &value );
 
 	return( 0 );
 }

libvips/iofuncs/type.c

@@ -502,6 +502,31 @@ transform_save_string_ref_string( const GValue *src_value, GValue *dest_value )
 		vips_value_get_save_string( src_value ) );
 }
 
+/**
+ * vips_ref_string_new: 
+ * @str: (transfer none): string to store
+ *
+ * Create a new refstring. These are reference-counted immutable strings, used
+ * to store string data in vips image metadata.
+ *
+ * See also: vips_area_unref().
+ *
+ * Returns: (transfer full): the new #VipsRefString.
+ */
+VipsRefString *
+vips_ref_string_new( const char *str )
+{
+	VipsArea *area;
+
+	area = vips_area_new( (VipsCallbackFn) g_free, g_strdup( str ) );
+
+	/* Handy place to cache this.
+	 */
+	area->length = strlen( str );
+
+	return( (VipsRefString *) area );
+}
+
 /**
  * vips_ref_string_get:
  * @refstr: the #VipsRefString to fetch from
@@ -1311,20 +1336,12 @@ vips_value_get_ref_string( const GValue *value, size_t *length )
 void
 vips_value_set_ref_string( GValue *value, const char *str )
 {
-	VipsArea *area;
-	char *str_copy;
+	VipsRefString *ref_str;
 
 	g_assert( G_VALUE_TYPE( value ) == VIPS_TYPE_REF_STRING );
-
-	str_copy = g_strdup( str );
-	area = vips_area_new( (VipsCallbackFn) vips_free, str_copy );
-
-	/* Handy place to cache this.
-	 */
-	area->length = strlen( str );
-
-	g_value_set_boxed( value, area );
-	vips_area_unref( area );
+	ref_str = vips_ref_string_new( str );
+	g_value_set_boxed( value, ref_str );
+	vips_area_unref( VIPS_AREA( ref_str ) );
 }
 
 /** 

python/Vips.py

@@ -55,6 +55,7 @@ vips_type_array_image = GObject.GType.from_name("VipsArrayImage")
 vips_type_blob = GObject.GType.from_name("VipsBlob")
 vips_type_image = GObject.GType.from_name("VipsImage")
 vips_type_operation = GObject.GType.from_name("VipsOperation")
+vips_type_ref_string = GObject.GType.from_name("VipsRefString")
 
 def is_2D(value):
     if not isinstance(value, list):