WIP: Add GtkPropertyAnimation

A GtkAnimation subclass that interpolates a GObject property.

gtk/gtkpropertyanimation.c

@@ -0,0 +1,49 @@
+/* gtkpropertyanimation.c: An animation controlling a single property
+ *
+ * Copyright 2019  GNOME Foundation
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * 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/>.
+ */
+
+#include "gtkpropertyanimation.h"
+
+#include "gtktransitionprivate.h"
+
+enum
+{
+  INITIAL,
+  FINAL,
+  N_STATES
+};
+
+struct _GtkPropertyAnimation
+{
+  GtkTransition parent_instance;
+
+  GValue interval[N_STATES];
+};
+
+G_DEFINE_TYPE (GtkPropertyAnimation, gtk_property_animation, GTK_TYPE_ANIMATION)
+
+static void
+gtk_property_animation_class_init (GtkPropertyAnimationClass *klass)
+{
+}
+
+static void
+gtk_property_animation_init (GtkPropertyAnimation *self)
+{
+}

gtk/gtkpropertyanimation.h

@@ -0,0 +1,52 @@
+/* gtkpropertyanimation.h: An animation controlling a single object property
+ *
+ * Copyright 2019  GNOME Foundation
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * 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/>.
+ */
+
+#pragma once
+
+#include <gtk/gtkanimation.h>
+
+G_BEGIN_DECLS
+
+/**
+ * GtkPropertyAnimation:
+ *
+ * A animation that operates on a single property of a #GObject.
+ */
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkPropertyAnimation, gtk_property_animation, GTK, PROPERTY_ANIMATION, GtkAnimation)
+
+GDK_AVAILABLE_IN_ALL
+GtkAnimation *          gtk_property_animation_new             (const char           *property_name);
+
+/* Interval */
+GDK_AVAILABLE_IN_ALL
+void                    gtk_property_animation_set_from        (GtkPropertyAnimation *animation,
+                                                                 ...);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_property_animation_set_from_value  (GtkPropertyAnimation *animation,
+                                                                 const GValue        *value);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_property_animation_set_to          (GtkPropertyAnimation *animation,
+                                                                 ...);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_property_animation_set_to_value    (GtkPropertyAnimation *animation,
+                                                                 const GValue         *value);
+
+G_END_DECLS