[libhandy/wip/haecker-felix/flap-widget: 15/20] animation: Add HdyAnimation

[Alexander Mikhaylenko <alexm src gnome org>]

commit 819d147c3a032e5aa43732c710f5b17be1cf9fc6
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Wed Nov 25 15:22:21 2020 +0500

    animation: Add HdyAnimation
    
    Add a tweener helper, this will make it significantly easier to do
    animations.
    
    Keep it private because the API is very barebones and we probably don't
    want anything for GTK 3 at this point anyway.

 src/hdy-animation-private.h |  30 ++++++++
 src/hdy-animation.c         | 169 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 198 insertions(+), 1 deletion(-)
---
diff --git a/src/hdy-animation-private.h b/src/hdy-animation-private.h
index f31002ad..ed6362f0 100644
--- a/src/hdy-animation-private.h
+++ b/src/hdy-animation-private.h
@@ -14,6 +14,36 @@
 
 G_BEGIN_DECLS
 
+#define HDY_TYPE_ANIMATION (hdy_animation_get_type())
+
+typedef struct _HdyAnimation HdyAnimation;
+
+typedef void   (*HdyAnimationValueCallback) (gdouble  value,
+                                             gpointer user_data);
+typedef void   (*HdyAnimationDoneCallback)  (gpointer user_data);
+typedef double (*HdyAnimationEasingFunc)    (gdouble  t);
+
+GType         hdy_animation_get_type  (void) G_GNUC_CONST;
+
+HdyAnimation *hdy_animation_new       (GtkWidget                 *widget,
+                                       gdouble                    from,
+                                       gdouble                    to,
+                                       gint64                     duration,
+                                       HdyAnimationEasingFunc     easing_func,
+                                       HdyAnimationValueCallback  value_cb,
+                                       HdyAnimationDoneCallback   done_cb,
+                                       gpointer                   user_data);
+
+HdyAnimation *hdy_animation_ref       (HdyAnimation *self);
+void          hdy_animation_unref     (HdyAnimation *self);
+
+void          hdy_animation_start     (HdyAnimation *self);
+void          hdy_animation_stop      (HdyAnimation *self);
+
+gdouble       hdy_animation_get_value (HdyAnimation *self);
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (HdyAnimation, hdy_animation_unref)
+
 gdouble hdy_lerp (gdouble a, gdouble b, gdouble t);
 
 G_END_DECLS
diff --git a/src/hdy-animation.c b/src/hdy-animation.c
index ce5bf64f..66ed3d64 100644
--- a/src/hdy-animation.c
+++ b/src/hdy-animation.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Purism SPC
+ * Copyright (C) 2019-2020 Purism SPC
  *
  * SPDX-License-Identifier: LGPL-2.1+
  */
@@ -18,6 +18,173 @@
  * Since: 0.0.11
  */
 
+G_DEFINE_BOXED_TYPE (HdyAnimation, hdy_animation, hdy_animation_ref, hdy_animation_unref)
+
+struct _HdyAnimation
+{
+  gatomicrefcount ref_count;
+
+  GtkWidget *widget;
+
+  gdouble value;
+
+  gdouble value_from;
+  gdouble value_to;
+  gint64 duration; /* ms */
+
+  gint64 start_time; /* ms */
+  guint tick_cb_id;
+
+  HdyAnimationEasingFunc easing_func;
+  HdyAnimationValueCallback value_cb;
+  HdyAnimationDoneCallback done_cb;
+  gpointer user_data;
+};
+
+static void
+set_value (HdyAnimation *self,
+           gdouble       value)
+{
+  self->value = value;
+  self->value_cb (value, self->user_data);
+}
+
+static gboolean
+tick_cb (GtkWidget     *widget,
+         GdkFrameClock *frame_clock,
+         HdyAnimation  *self)
+{
+  gint64 frame_time = gdk_frame_clock_get_frame_time (frame_clock) / 1000; /* ms */
+  gdouble t = (gdouble) (frame_time - self->start_time) / self->duration;
+
+  if (t >= 1) {
+    self->tick_cb_id = 0;
+
+    set_value (self, self->value_to);
+
+    g_signal_handlers_disconnect_by_func (self->widget, hdy_animation_stop, self);
+
+    self->done_cb (self->user_data);
+
+    return G_SOURCE_REMOVE;
+  }
+
+  set_value (self, hdy_lerp (self->value_from, self->value_to, self->easing_func (t)));
+
+  return G_SOURCE_CONTINUE;
+}
+
+static void
+hdy_animation_free (HdyAnimation *self)
+{
+  hdy_animation_stop (self);
+
+  g_slice_free (HdyAnimation, self);
+}
+
+HdyAnimation *
+hdy_animation_new (GtkWidget                 *widget,
+                   gdouble                    from,
+                   gdouble                    to,
+                   gint64                     duration,
+                   HdyAnimationEasingFunc     easing_func,
+                   HdyAnimationValueCallback  value_cb,
+                   HdyAnimationDoneCallback   done_cb,
+                   gpointer                   user_data)
+{
+  HdyAnimation *self;
+
+  g_return_val_if_fail (GTK_IS_WIDGET (widget), NULL);
+  g_return_val_if_fail (easing_func != NULL, NULL);
+  g_return_val_if_fail (value_cb != NULL, NULL);
+  g_return_val_if_fail (done_cb != NULL, NULL);
+
+  self = g_slice_new0 (HdyAnimation);
+
+  g_atomic_ref_count_init (&self->ref_count);
+
+  self->widget = widget;
+  self->value_from = from;
+  self->value_to = to;
+  self->duration = duration;
+  self->easing_func = easing_func;
+  self->value_cb = value_cb;
+  self->done_cb = done_cb;
+  self->user_data = user_data;
+
+  self->value = from;
+
+  return self;
+}
+
+HdyAnimation *
+hdy_animation_ref (HdyAnimation *self)
+{
+  g_return_val_if_fail (self != NULL, NULL);
+
+  g_atomic_ref_count_inc (&self->ref_count);
+
+  return self;
+}
+
+void
+hdy_animation_unref (HdyAnimation *self)
+{
+  g_return_if_fail (self != NULL);
+
+  if (g_atomic_ref_count_dec (&self->ref_count))
+    hdy_animation_free (self);
+}
+
+void
+hdy_animation_start (HdyAnimation *self)
+{
+  g_return_if_fail (self != NULL);
+
+  if (!hdy_get_enable_animations (self->widget) ||
+      !gtk_widget_get_mapped (self->widget) ||
+      self->duration <= 0) {
+    set_value (self, self->value_to);
+
+    self->done_cb (self->user_data);
+
+    return;
+  }
+
+  self->start_time = gdk_frame_clock_get_frame_time (gtk_widget_get_frame_clock (self->widget)) / 1000;
+
+  if (self->tick_cb_id)
+    return;
+
+  g_signal_connect_swapped (self->widget, "unmap",
+                            G_CALLBACK (hdy_animation_stop), self);
+  self->tick_cb_id = gtk_widget_add_tick_callback (self->widget, (GtkTickCallback) tick_cb, self, NULL);
+}
+
+void
+hdy_animation_stop (HdyAnimation *self)
+{
+  g_return_if_fail (self != NULL);
+
+  if (!self->tick_cb_id)
+    return;
+
+  gtk_widget_remove_tick_callback (self->widget, self->tick_cb_id);
+  self->tick_cb_id = 0;
+
+  g_signal_handlers_disconnect_by_func (self->widget, hdy_animation_stop, self);
+
+  self->done_cb (self->user_data);
+}
+
+gdouble
+hdy_animation_get_value (HdyAnimation *self)
+{
+  g_return_val_if_fail (self != NULL, 0.0);
+
+  return self->value;
+}
+
 /**
  * hdy_get_enable_animations:
  * @widget: a #GtkWidget