return built-in enums as strings

we now return strings for things like `vips_image_get($image, "interpretation")`

previously these came back as ints due to the way libvips handles the
getter for built-in properties

Author: jcupitt

ChangeLog

@@ -5,7 +5,8 @@ Version 0.1.1 (2016-10-03)
 	* Support draw operations
 	* Add vips_error_buffer(), remove docref messages
 	* Return 0/-1 everywhere for error
-	* Vips_image_get() returns ["out" => value] | -1
+	* vips_image_get() returns ["out" => value] | -1
+	* vips_image_get() returns built-in enums as strings
 	* Fix type conversions
 	* Add vips_image_remove()
 	* Add vips_cache_set_*() 

tests/004.phpt

@@ -13,9 +13,3 @@ vips can get image header fields
 ?>
 --EXPECT--
 pass
---CLEAN--
-<?php
-  $output_filename = dirname(__FILE__) . "/x.tif";
-  unlink($output_filename);
-?>
-

tests/030.phpt

@@ -0,0 +1,15 @@
+--TEST--
+enum fields are returned as strings
+--SKIPIF--
+<?php if (!extension_loaded("vips")) print "skip"; ?>
+--FILE--
+<?php 
+  $filename = dirname(__FILE__) . "/images/img_0076.jpg";
+  $image = vips_image_new_from_file($filename)["out"];
+  $interpretation = vips_image_get($image, "interpretation")["out"];
+  if ($interpretation == "srgb") {
+    echo("pass\n");
+  }
+?>
+--EXPECT--
+pass

vips.c

@@ -1254,6 +1254,7 @@ PHP_FUNCTION(vips_image_get)
 	VipsImage *image;
 	GValue gvalue = { 0 };
 	zval zvalue;
+	GParamSpec *pspec;
 
 	if (zend_parse_parameters(ZEND_NUM_ARGS(), "rs", 
 		&im, &field_name, &field_name_len) == FAILURE) {
@@ -1265,7 +1266,20 @@ PHP_FUNCTION(vips_image_get)
 		RETURN_LONG(-1);
 	}
 
-	if (vips_image_get(image, field_name, &gvalue)) {
+	/* Ugly: older libvipses would return enums from the true header fields 
+	 * (eg. ->interpretation) as ints, but we want to send a string back
+	 * for things like this.
+	 *
+	 * Test if field_name exists as a regular glib property and if it does, use
+	 * g_object_get(). Otherwise use vips_image_get(), since it can read extra
+	 * image metadata.
+	 */
+	if ((pspec = g_object_class_find_property(G_OBJECT_GET_CLASS(image), 
+		field_name))) {
+		g_value_init(&gvalue, G_PARAM_SPEC_VALUE_TYPE(pspec));
+		g_object_get_property(G_OBJECT(image), field_name, &gvalue);
+	} 
+	else if (vips_image_get(image, field_name, &gvalue)) {
 		RETURN_LONG(-1);
 	}