css: Add animation support

This adds the GtkCssAnimation class and the code needed to hook it into
GtkStyleContext. It takes the values out of the CSS "animation"
properties and does animations. See
  http://dev.w3.org/csswg/css3-animations/
for details.

Note that the code for starting and stopping animations with widget
visibility doesn't work yet.

1 files changed, 214 insertions, 0 deletions

diff --git a/gtk/gtkcssanimation.c b/gtk/gtkcssanimation.c
new file mode 100644
index 0000000000..765bb4e750
--- /dev/null
+++ b/gtk/gtkcssanimation.c
@@ -0,0 +1,214 @@
+/*
+ * Copyright © 2012 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: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "config.h"
+
+#include "gtkcssanimationprivate.h"
+
+#include "gtkcsseasevalueprivate.h"
+
+#include <math.h>
+
+G_DEFINE_TYPE (GtkCssAnimation, _gtk_css_animation, GTK_TYPE_STYLE_ANIMATION)
+
+/* NB: Return value can be negative and +-Inf */
+static double
+gtk_css_animation_get_iteration (GtkCssAnimation *animation,
+                                 gint64           for_time_us)
+{
+  gint64 elapsed;
+  double iterations;
+
+  elapsed = for_time_us - animation->timestamp;
+  iterations = (double) elapsed / animation->duration;
+
+  return iterations;
+}
+
+static gboolean
+gtk_css_animation_is_executing_at_iteration (GtkCssAnimation *animation,
+                                             double           iteration)
+{
+  switch (animation->fill_mode)
+    {
+    case GTK_CSS_FILL_NONE:
+      return iteration >= 0 && iteration <= animation->iteration_count;
+    case GTK_CSS_FILL_FORWARDS:
+      return iteration >= 0;
+    case GTK_CSS_FILL_BACKWARDS:
+      return iteration <= animation->iteration_count;
+    case GTK_CSS_FILL_BOTH:
+      return TRUE;
+    default:
+      g_return_val_if_reached (FALSE);
+    }
+}
+
+static double
+gtk_css_animation_get_progress_from_iteration (GtkCssAnimation *animation,
+                                               double           iteration)
+{
+  double d;
+
+  iteration = CLAMP (iteration, 0, animation->iteration_count);
+
+  switch (animation->direction)
+    {
+    case GTK_CSS_DIRECTION_NORMAL:
+      if (iteration == animation->iteration_count)
+        return 1;
+      else
+        return iteration - floor (iteration);
+    case GTK_CSS_DIRECTION_REVERSE:
+      if (iteration == animation->iteration_count)
+        return 1;
+      else
+        return ceil (iteration) - iteration;
+    case GTK_CSS_DIRECTION_ALTERNATE:
+      d = floor (iteration);
+      if (fmod (d, 2))
+        return iteration - d;
+      else
+        return 1 + d - iteration;
+    case GTK_CSS_DIRECTION_ALTERNATE_REVERSE:
+      d = floor (iteration);
+      if (fmod (d, 2))
+        return 1 + d - iteration;
+      else
+        return iteration - d;
+    default:
+      g_return_val_if_reached (0);
+    }
+}
+
+static GtkBitmask *
+gtk_css_animation_set_values (GtkStyleAnimation    *style_animation,
+                              GtkBitmask           *changed,
+                              gint64                for_time_us,
+                              GtkCssComputedValues *values)
+{
+  GtkCssAnimation *animation = GTK_CSS_ANIMATION (style_animation);
+  double iteration, progress;
+  guint i;
+
+  iteration = gtk_css_animation_get_iteration (animation, for_time_us);
+
+  if (!gtk_css_animation_is_executing_at_iteration (animation, iteration))
+    return changed;
+
+  progress = gtk_css_animation_get_progress_from_iteration (animation, iteration);
+  progress = _gtk_css_ease_value_transform (animation->ease, progress);
+  
+  for (i = 0; i < _gtk_css_keyframes_get_n_properties (animation->keyframes); i++)
+    {
+      GtkCssValue *value;
+      guint property_id;
+      
+      property_id = _gtk_css_keyframes_get_property_id (animation->keyframes, i);
+
+      value = _gtk_css_keyframes_get_value (animation->keyframes,
+                                            i,
+                                            progress,
+                                            _gtk_css_computed_values_get_value (values, i));
+      /* XXX: Is using 0 correct here? */
+      _gtk_css_computed_values_set_value (values, property_id, value, 0, NULL);
+      _gtk_css_value_unref (value);
+      
+      changed = _gtk_bitmask_set (changed, property_id, TRUE);
+    }
+
+  return changed;
+}
+
+static gboolean
+gtk_css_animation_is_finished (GtkStyleAnimation *style_animation,
+                               gint64             at_time_us)
+{
+  return FALSE;
+}
+
+static void
+gtk_css_animation_finalize (GObject *object)
+{
+  GtkCssAnimation *animation = GTK_CSS_ANIMATION (object);
+
+  g_free (animation->name);
+  _gtk_css_keyframes_unref (animation->keyframes);
+  _gtk_css_value_unref (animation->ease);
+
+  G_OBJECT_CLASS (_gtk_css_animation_parent_class)->finalize (object);
+}
+
+static void
+_gtk_css_animation_class_init (GtkCssAnimationClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkStyleAnimationClass *animation_class = GTK_STYLE_ANIMATION_CLASS (klass);
+
+  object_class->finalize = gtk_css_animation_finalize;
+
+  animation_class->set_values = gtk_css_animation_set_values;
+  animation_class->is_finished = gtk_css_animation_is_finished;
+}
+
+static void
+_gtk_css_animation_init (GtkCssAnimation *animation)
+{
+}
+
+GtkStyleAnimation *
+_gtk_css_animation_new (const char      *name,
+                        GtkCssKeyframes *keyframes,
+                        gint64           start_time_us,
+                        gint64           duration_us,
+                        GtkCssValue     *ease,
+                        GtkCssDirection  direction,
+                        GtkCssPlayState  play_state,
+                        GtkCssFillMode   fill_mode,
+                        double           iteration_count)
+{
+  GtkCssAnimation *animation;
+
+  g_return_val_if_fail (name != NULL, NULL);
+  g_return_val_if_fail (keyframes != NULL, NULL);
+  g_return_val_if_fail (ease != NULL, NULL);
+  g_return_val_if_fail (iteration_count >= 0, NULL);
+
+  animation = g_object_new (GTK_TYPE_CSS_ANIMATION, NULL);
+
+  animation->name = g_strdup (name);
+  animation->keyframes = _gtk_css_keyframes_ref (keyframes);
+  animation->timestamp = start_time_us;
+  animation->duration = duration_us;
+  animation->ease = _gtk_css_value_ref (ease);
+  animation->direction = direction;
+  animation->play_state = play_state;
+  animation->fill_mode = fill_mode;
+  animation->iteration_count = iteration_count;
+
+  return GTK_STYLE_ANIMATION (animation);
+}
+
+const char *
+_gtk_css_animation_get_name (GtkCssAnimation *animation)
+{
+  g_return_val_if_fail (GTK_IS_CSS_ANIMATION (animation), NULL);
+
+  return animation->name;
+}