Add a constraint editor demo

This is an initial cut at providing a tool
for interactive exploration of constraints.

demos/constraint-editor/constraint-view-child.c

@@ -0,0 +1,93 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "constraint-view-child.h"
+
+struct _ConstraintViewChild
+{
+  GObject parent_instance;
+
+  char *name;
+};
+
+enum {
+  PROP_NAME = 1,
+  LAST_PROP
+};
+
+static GParamSpec props[LAST_PROP];
+
+G_DEFINE_TYPE (ConstraintViewChild, constraint_view_child, G_TYPE_OBJECT)
+
+static void
+constraint_view_child_init (ConstraintViewChild *child)
+{
+}
+
+static void
+constraint_view_child_finalize (GObject *object)
+{
+  ConstraintViewChild *child = CONSTRAINT_VIEW_CHILD (object);
+
+  g_free (child->name);
+
+  G_OBJECT_CLASS (constraint_view_child_parent_class)->finalize (object);
+}
+
+static void
+constraint_view_child_set_property (GObject *object,
+                                    
+static void
+constraint_view_child_class_init (ConstraintViewChildClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->finalize = constraint_view_child_finalize;
+  object_class->get_property = constraint_view_child_get_property;
+  object_class->set_property = constraint_view_child_set_property;
+
+  props[PROP_NAME] =
+    g_param_spec_string ("name", "name", "name",
+                         NULL,
+                         G_PARAM_READWRITE);
+
+  g_object_class_install_properties (object_class, LAST_PROP, props);
+}
+
+#define CONSTRAINT_VIEW_CHILD_TYPE (constraint_view_get_type ())
+
+G_DECLARE_TYPE (ConstraintViewChild, constraint_view_child, CONSTRAINT, VIEW_CHILD, GObject)
+
+#define CONSTRAINT_VIEW_WIDGET_TYPE (constraint_view_widget_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewWidget, constraint_view_widget, CONSTRAINT, VIEW_WIDGET, ConstraintViewChild)
+
+ConstraintViewWidget * constraint_view_widget_new (void);
+
+#define CONSTRAINT_VIEW_GUIDE_TYPE (constraint_view_guide_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewGuide, constraint_view_guide, CONSTRAINT, VIEW_GUIDE, ConstraintViewChild)
+
+ConstraintViewGuide * constraint_view_guide_new (void);
+
+#define CONSTRAINT_VIEW_CONSTRAINT_TYPE (constraint_view_constraint_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewConstraint, constraint_view_constraint, CONSTRAINT, VIEW_CONSTRAINT, ConstraintViewChild)
+
+ConstraintViewGuide * constraint_view_constraint_new (void);