python: expose plugin configuration as well.

In both PluginMetadata and AbstractPlugin itself. This makes the
pluginmanager module depend on the utility module (which currently
contains just the Configuration bindings).

src/python/corrade/corrade.cpp

@@ -128,12 +128,14 @@ PYBIND11_MODULE(_corrade, m) {
     py::module_ containers = m.def_submodule("containers");
     corrade::containers(containers);
 
+    py::module_ utility = m.def_submodule("utility");
+    corrade::utility(utility);
+
+    /* PluginManager needs Utility::ConfigurationGroup, needs to be defined
+       after */
     #ifdef Corrade_PluginManager_FOUND
     py::module_ pluginmanager = m.def_submodule("pluginmanager");
     corrade::pluginmanager(pluginmanager);
     #endif
-
-    py::module_ utility = m.def_submodule("utility");
-    corrade::utility(utility);
     #endif
 }

src/python/corrade/pluginmanager.cpp

@@ -32,6 +32,7 @@
 #include <Corrade/PluginManager/AbstractManager.h>
 #include <Corrade/PluginManager/AbstractPlugin.h>
 #include <Corrade/PluginManager/PluginMetadata.h>
+#include <Corrade/Utility/ConfigurationGroup.h>
 
 #include "Corrade/PythonBindings.h"
 
@@ -43,6 +44,13 @@ namespace corrade {
 void pluginmanager(py::module_& m) {
     m.doc() = "Plugin management";
 
+    #ifndef CORRADE_BUILD_STATIC
+    /* Need ConfigurationGroup from there. These are a part of the same module
+       in the static build, no need to import (also can't import because there
+       it's _corrade.*) */
+    py::module_::import("corrade.utility");
+    #endif
+
     py::enum_<PluginManager::LoadState> loadState{m, "LoadState", "Plugin load state"};
     loadState
         .value("NOT_FOUND", PluginManager::LoadState::NotFound)
@@ -62,7 +70,9 @@ void pluginmanager(py::module_& m) {
         .def_property_readonly("name", &PluginManager::PluginMetadata::name, "Plugin name")
         .def_property_readonly("depends", &PluginManager::PluginMetadata::depends, "Plugins on which this plugin depends")
         .def_property_readonly("used_by", &PluginManager::PluginMetadata::usedBy, "Plugins which depend on this plugin")
-        .def_property_readonly("provides", &PluginManager::PluginMetadata::provides, "Plugins which are provided by this plugin");
+        .def_property_readonly("provides", &PluginManager::PluginMetadata::provides, "Plugins which are provided by this plugin")
+        /** @todo data? no plugin uses this at the moment */
+        .def_property_readonly("configuration", static_cast<Utility::ConfigurationGroup&(PluginManager::PluginMetadata::*)()>(&PluginManager::PluginMetadata::configuration), "Initial plugin-specific configuration", py::return_value_policy::reference_internal);
 
     PyNonDestructibleClass<PluginManager::AbstractManager> manager{m, "AbstractManager", "Base for plugin managers"};
     manager.attr("VERSION") = PluginManager::AbstractManager::Version;
@@ -143,7 +153,8 @@ void pluginmanager(py::module_& m) {
             /** @todo drop std::string in favor of our own string caster */
             return std::string{self.plugin()};
         }, "Plugin identifier string")
-        .def_property_readonly("metadata", &PluginManager::AbstractPlugin::metadata, "Plugin metadata", py::return_value_policy::reference_internal);
+        .def_property_readonly("metadata", &PluginManager::AbstractPlugin::metadata, "Plugin metadata", py::return_value_policy::reference_internal)
+        .def_property_readonly("configuration", static_cast<Utility::ConfigurationGroup&(PluginManager::AbstractPlugin::*)()>(&PluginManager::AbstractPlugin::configuration), "Plugin-specific configuration", py::return_value_policy::reference_internal);
 }
 
 }

src/python/magnum/test/test_trade.py

@@ -1081,6 +1081,40 @@ class Importer(unittest.TestCase):
         del metadata
         self.assertEqual(sys.getrefcount(manager), manager_refcount)
 
+    def test_configuration(self):
+        manager = trade.ImporterManager()
+
+        metadata = manager.metadata('StbImageImporter')
+        metadata_refcount = sys.getrefcount(metadata)
+
+        # Setting the value from initial configuration should make the plugin
+        # inherit that
+        initial_configuration = metadata.configuration
+        self.assertEqual(sys.getrefcount(metadata), metadata_refcount + 1)
+        self.assertEqual(initial_configuration['forceChannelCount'], '0')
+        initial_configuration['forceChannelCount'] = '7'
+
+        del initial_configuration
+        self.assertEqual(sys.getrefcount(metadata), metadata_refcount)
+
+        importer = manager.load_and_instantiate('StbImageImporter')
+        importer_refcount = sys.getrefcount(importer)
+
+        configuration = importer.configuration
+        self.assertEqual(sys.getrefcount(importer), importer_refcount + 1)
+        self.assertEqual(configuration['forceChannelCount'], '7')
+
+        configuration['forceChannelCount'] = '2'
+
+        del configuration
+        self.assertEqual(sys.getrefcount(importer), importer_refcount)
+
+        # Verify the config change is actually used and not being done on some
+        # copy that gets thrown away
+        importer.open_file(os.path.join(os.path.dirname(__file__), 'rgb.png'))
+        image = importer.image2d(0)
+        self.assertEqual(image.format, PixelFormat.RG8_UNORM) # not RGB8
+
     def test_no_file_opened(self):
         importer = trade.ImporterManager().load_and_instantiate('StbImageImporter')
         self.assertFalse(importer.is_opened)