[libadwaita] timed-animation: Add alternate and reverse

[Alexander Mikhaylenko <alexm src gnome org>]

commit 6eaf28868b36661afb4728f934fde0d1352391fb
Author: Manuel Genovés <manuel genoves gmail com>
Date:   Tue Nov 16 14:11:29 2021 +0500

    timed-animation: Add alternate and reverse

 src/adw-timed-animation-private.h |  8 ++++
 src/adw-timed-animation.c         | 90 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 97 insertions(+), 1 deletion(-)
---
diff --git a/src/adw-timed-animation-private.h b/src/adw-timed-animation-private.h
index 18463aaa..6d284d7e 100644
--- a/src/adw-timed-animation-private.h
+++ b/src/adw-timed-animation-private.h
@@ -55,4 +55,12 @@ guint adw_timed_animation_get_repeat_count (AdwTimedAnimation *self);
 void  adw_timed_animation_set_repeat_count (AdwTimedAnimation *self,
                                             guint              repeat_count);
 
+gboolean adw_timed_animation_get_reverse (AdwTimedAnimation *self);
+void     adw_timed_animation_set_reverse (AdwTimedAnimation *self,
+                                          gboolean           reverse);
+
+gboolean adw_timed_animation_get_alternate (AdwTimedAnimation *self);
+void     adw_timed_animation_set_alternate (AdwTimedAnimation *self,
+                                            gboolean           alternate);
+
 G_END_DECLS
diff --git a/src/adw-timed-animation.c b/src/adw-timed-animation.c
index b7a3e54c..c78c1762 100644
--- a/src/adw-timed-animation.c
+++ b/src/adw-timed-animation.c
@@ -19,6 +19,8 @@ struct _AdwTimedAnimation
   double value_to;
   guint duration; /* ms */
   guint repeat_count;
+  gboolean reverse;
+  gboolean alternate;
 
   AdwAnimationInterpolator interpolator;
 };
@@ -37,6 +39,8 @@ enum {
   PROP_DURATION,
   PROP_INTERPOLATOR,
   PROP_REPEAT_COUNT,
+  PROP_REVERSE,
+  PROP_ALTERNATE,
   LAST_PROP,
 };
 
@@ -58,19 +62,29 @@ adw_timed_animation_calculate_value (AdwAnimation *animation,
                                      guint         t)
 {
   AdwTimedAnimation *self = ADW_TIMED_ANIMATION (animation);
+
   double value;
   double iteration, progress;
+  gboolean reverse = false;
 
   if (self->duration == 0)
     return self->value_to;
 
   progress = modf (((double) t / self->duration), &iteration);
 
+  if (self->alternate)
+    reverse = ((int) iteration % 2);
+
+  if (self->reverse)
+    reverse = !reverse;
+
   /* When the animation ends, return the exact final value, which depends on the
      direction the animation is going at that moment, having into account that at the
      time of this check we're already on the next iteration. */
   if (t >= adw_timed_animation_estimate_duration (animation))
-    return self->value_to;
+    return self->alternate == reverse ? self->value_to : self->value_from;
+
+  progress = reverse ? (1 - progress) : progress;
 
   switch (self->interpolator) {
     case ADW_ANIMATION_INTERPOLATOR_EASE_IN:
@@ -118,6 +132,14 @@ adw_timed_animation_get_property (GObject    *object,
     g_value_set_uint (value, adw_timed_animation_get_repeat_count (self));
     break;
 
+  case PROP_REVERSE:
+    g_value_set_boolean (value, adw_timed_animation_get_reverse (self));
+    break;
+
+  case PROP_ALTERNATE:
+    g_value_set_boolean (value, adw_timed_animation_get_alternate (self));
+    break;
+
   default:
     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
   }
@@ -152,6 +174,14 @@ adw_timed_animation_set_property (GObject      *object,
     adw_timed_animation_set_repeat_count (self, g_value_get_uint (value));
     break;
 
+  case PROP_REVERSE:
+    adw_timed_animation_set_reverse (self, g_value_get_boolean (value));
+    break;
+
+  case PROP_ALTERNATE:
+    adw_timed_animation_set_alternate (self, g_value_get_boolean (value));
+    break;
+
   default:
     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
   }
@@ -213,6 +243,20 @@ adw_timed_animation_class_init (AdwTimedAnimationClass *klass)
                        1,
                        G_PARAM_READWRITE | G_PARAM_CONSTRUCT);
 
+  props[PROP_REVERSE] =
+    g_param_spec_boolean ("reverse",
+                          "Reverse",
+                          "Wheter the animation should play backwards",
+                          FALSE,
+                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT);
+
+  props[PROP_ALTERNATE] =
+    g_param_spec_boolean ("alternate",
+                          "Alternate",
+                          "Whether the animation should change direction each time",
+                          FALSE,
+                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT);
+
   g_object_class_install_properties (object_class, LAST_PROP, props);
 }
 
@@ -357,3 +401,47 @@ adw_timed_animation_set_repeat_count (AdwTimedAnimation *self,
 
   g_object_notify_by_pspec (G_OBJECT (self), props[PROP_REPEAT_COUNT]);
 }
+
+gboolean
+adw_timed_animation_get_reverse (AdwTimedAnimation *self)
+{
+  g_return_val_if_fail (ADW_IS_TIMED_ANIMATION (self), FALSE);
+
+  return self->reverse;
+}
+
+void
+adw_timed_animation_set_reverse (AdwTimedAnimation *self,
+                                 gboolean           reverse)
+{
+  g_return_if_fail (ADW_IS_TIMED_ANIMATION (self));
+
+  if (self->reverse == reverse)
+    return;
+
+  self->reverse = reverse;
+
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_REVERSE]);
+}
+
+gboolean
+adw_timed_animation_get_alternate (AdwTimedAnimation *self)
+{
+  g_return_val_if_fail (ADW_IS_TIMED_ANIMATION (self), FALSE);
+
+  return self->alternate;
+}
+
+void
+adw_timed_animation_set_alternate (AdwTimedAnimation *self,
+                                   gboolean           alternate)
+{
+  g_return_if_fail (ADW_IS_TIMED_ANIMATION (self));
+
+  if (self->alternate == alternate)
+    return;
+
+  self->alternate = alternate;
+
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_ALTERNATE]);
+}