1 files changed, 65 insertions, 0 deletions
diff --git a/src/animation/gtd-animation-utils.h b/src/animation/gtd-animation-utils.h
new file mode 100644
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+++ b/src/animation/gtd-animation-utils.h
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+/* gtd-animation-utils.h
+ *
+ * Copyright 2020 Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <glib-object.h>
+
+G_BEGIN_DECLS
+
+
+/**
+ * GtdProgressFunc:
+ * @a: the initial value of an interval
+ * @b: the final value of an interval
+ * @progress: the progress factor, between 0 and 1
+ * @retval: the value used to store the progress
+ *
+ * Prototype of the progress function used to compute the value
+ * between the two ends @a and @b of an interval depending on
+ * the value of @progress.
+ *
+ * The #GValue in @retval is already initialized with the same
+ * type as @a and @b.
+ *
+ * This function will be called by #GtdInterval if the
+ * type of the values of the interval was registered using
+ * gtd_interval_register_progress_func().
+ *
+ * Return value: %TRUE if the function successfully computed
+ *   the value and stored it inside @retval
+ */
+typedef gboolean (* GtdProgressFunc) (const GValue *a,
+                                      const GValue *b,
+                                      gdouble       progress,
+                                      GValue       *retval);
+
+void            gtd_interval_register_progress_func (GType           value_type,
+                                                     GtdProgressFunc func);
+
+
+gboolean        gtd_has_progress_function  (GType gtype);
+gboolean        gtd_run_progress_function  (GType         gtype,
+                                            const GValue *initial,
+                                            const GValue *final,
+                                            gdouble       progress,
+                                            GValue       *retval);
+
+G_END_DECLS