allow optional output args

optional output args in C API startup ... need to fix up C API shutdown,
plus CLI, see TODO notes

ChangeLog

@@ -1,8 +1,9 @@
 20/8/11 started 7.27.0
 - version bump for new dev cycle
-- im_subtract(), im_avg() redone as classes
+- im_subtract(), im_avg(), im_min(), im_minpos() redone as classes
 - added VIPS_ARGUMENT_APPEND to help control arg ordering
 - generate has a 'stop' param to signal successful early termination
+- added optional output args, eg. x/y for min
 
 10/8/11 started 7.26.3
 - don't use G_VALUE_COLLECT_INIT(), many platforms do not have a glib this

TODO

@@ -1,16 +1,30 @@
-- optional output args are broken
+- cmd line interface needs to print optional output args, if requested
+  
+  eg. 
+
+  	$ vips min fred.v
+	12
+  	$ vips min -x fred.v
+	12
+	300
+
+  the switch is there, but breaks an assert:
+
+	$ vips min -x babe.jpg
+	VIPS:ERROR:object.c:1178:vips_object_set_argument_from_string: assertion
+	failed: (argument_class->flags & VIPS_ARGUMENT_INPUT)
+	Aborted
+
+
+
+
+- C interface needs to look for optional output args in final psss, eg.
 
 	vips_min( im, &min,
 		"x", &xpos,
 		"y", &ypos,
 		NULL );
 
-  tries to set "x" and "y" during vips_operation_set_valist_optional(),
-  instead it should read them during output arg readout phase
-
-
-
-
 
 
 

libvips/iofuncs/object.c

@@ -702,7 +702,6 @@ vips_object_set_property( GObject *gobject,
 	}
 
 #ifdef DEBUG
-#endif /*DEBUG*/
 {
 	char *str_value;
 
@@ -712,6 +711,7 @@ vips_object_set_property( GObject *gobject,
 	printf( ".%s = %s\n", g_param_spec_get_name( pspec ), str_value );
 	g_free( str_value );
 }
+#endif /*DEBUG*/
 
 	g_assert( ((VipsArgument *) argument_class)->pspec == pspec );
 	g_assert( ((VipsArgument *) argument_instance)->pspec == pspec );

libvips/iofuncs/operation.c

@@ -302,10 +302,54 @@ vips_operation_set_valist_required( VipsOperation *operation, va_list ap )
 static int
 vips_operation_set_valist_optional( VipsOperation *operation, va_list ap )
 {
-	char *first_property_name;
+	VipsOperationClass *class = 
+		VIPS_OPERATION_GET_CLASS( operation );
+	VipsArgumentTable *argument_table =
+		VIPS_OBJECT_CLASS( class )->argument_table;
 
-	first_property_name = va_arg( ap, char * );
+	char *name;
-	g_object_set_valist( G_OBJECT (operation), first_property_name, ap );
+
+	name = va_arg( ap, char * );
+
+	while( name ) {
+		GValue value = { 0, };
+		GParamSpec *pspec;
+		gchar *error = NULL;
+		VipsArgumentClass *argument_class;
+
+		if( !(pspec = g_object_class_find_property( 
+			G_OBJECT_CLASS( class ), name )) ) {
+			vips_error( VIPS_OBJECT_CLASS( class )->description, 
+				_( "class `%s' has no property named `%s'\n" ),
+				G_OBJECT_TYPE_NAME( operation ), name );
+			return( -1 );
+		}
+
+		g_value_init( &value, G_PARAM_SPEC_VALUE_TYPE( pspec ) );
+		G_VALUE_COLLECT( &value, ap, 0, &error );
+		if( error ) {
+			vips_error( VIPS_OBJECT_CLASS( class )->description, 
+				"%s", _( error ) );
+			g_value_unset( &value );
+			g_free( error );
+
+			return( -1 );
+		}
+
+		/* Only set input args, Output args are read from the
+		 * finished object after build.
+		 */
+		argument_class = (VipsArgumentClass *)
+			vips__argument_table_lookup( argument_table, pspec );
+		if( argument_class &&
+			(argument_class->flags & VIPS_ARGUMENT_INPUT) ) 
+			g_object_set_property( G_OBJECT( operation ), 
+				name, &value );
+
+		g_value_unset( &value );
+
+		name = va_arg( ap, char * );
+	}
 
 	return( 0 );
 }