text: /*
   * 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 "gtkcsstransitionprivate.h"
  
  #include "gtkcsseasevalueprivate.h"
  #include "gtkprogresstrackerprivate.h"
  
  struct _GtkCssTransition
  {
    GtkStyleAnimation parent;
  
    guint               property;
    guint               finished;
    GtkCssValue        *start;
    GtkCssValue        *ease;
    GtkProgressTracker  tracker;
  };
  
  
  static GtkStyleAnimation *   gtk_css_transition_advance  (GtkStyleAnimation    *style_animation,
                                                            gint64                timestamp);
  
  
  
  static void
  gtk_css_transition_apply_values (GtkStyleAnimation   *style_animation,
                                   GtkCssAnimatedStyle *style)
  {
    GtkCssTransition *transition = (GtkCssTransition *)style_animation;
    GtkCssValue *value, *end;
    double progress;
    GtkProgressState state;
  
    if (transition->finished)
      return;
  
    end = gtk_css_animated_style_get_intrinsic_value (style, transition->property);
    state = gtk_progress_tracker_get_state (&transition->tracker);
  
    if (state == GTK_PROGRESS_STATE_BEFORE)
      value = _gtk_css_value_ref (transition->start);
    else if (state == GTK_PROGRESS_STATE_DURING)
      {
        progress = gtk_progress_tracker_get_progress (&transition->tracker, FALSE);
        progress = _gtk_css_ease_value_transform (transition->ease, progress);
  
        value = _gtk_css_value_transition (transition->start,
                                           end,
                                           transition->property,
                                           progress);
      }
    else
      return;
  
    if (value == NULL)
      value = _gtk_css_value_ref (end);
  
    gtk_css_animated_style_set_animated_value (style, transition->property, value);
  }
  
  static gboolean
  gtk_css_transition_is_finished (GtkStyleAnimation *animation)
  {
    GtkCssTransition *transition = (GtkCssTransition *)animation;
  
    return transition->finished;
  }
  
  static gboolean
  gtk_css_transition_is_static (GtkStyleAnimation *animation)
  {
    GtkCssTransition *transition = (GtkCssTransition *)animation;
  
    return transition->finished;
  }
  
  static void
  gtk_css_transition_free (GtkStyleAnimation *animation)
  {
    GtkCssTransition *self = (GtkCssTransition *)animation;
  
    gtk_css_value_unref (self->start);
    gtk_css_value_unref (self->ease);
  
    g_slice_free (GtkCssTransition, self);
  }
  
  static const GtkStyleAnimationClass GTK_CSS_TRANSITION_CLASS = {
    "GtkCssTransition",
    gtk_css_transition_free,
    gtk_css_transition_is_finished,
    gtk_css_transition_is_static,
    gtk_css_transition_apply_values,
    gtk_css_transition_advance,
  };
  
  static GtkStyleAnimation *
  gtk_css_transition_advance (GtkStyleAnimation    *style_animation,
                              gint64                timestamp)
  {
    GtkCssTransition *source = (GtkCssTransition *)style_animation;
    GtkCssTransition *transition;
  
    transition = g_slice_alloc (sizeof (GtkCssTransition));
    transition->parent.class = &GTK_CSS_TRANSITION_CLASS;
    transition->parent.ref_count = 1;
  
    transition->property = source->property;
    transition->start = _gtk_css_value_ref (source->start);
    transition->ease = _gtk_css_value_ref (source->ease);
  
    gtk_progress_tracker_init_copy (&source->tracker, &transition->tracker);
    gtk_progress_tracker_advance_frame (&transition->tracker, timestamp);
    transition->finished = gtk_progress_tracker_get_state (&transition->tracker) == GTK_PROGRESS_STATE_AFTER;
  
    return (GtkStyleAnimation *)transition;
  }
  GtkStyleAnimation *
  _gtk_css_transition_new (guint        property,
                           GtkCssValue *start,
                           GtkCssValue *ease,
                           gint64       timestamp,
                           gint64       duration_us,
                           gint64       delay_us)
  {
    GtkCssTransition *transition;
  
    g_return_val_if_fail (start != NULL, NULL);
    g_return_val_if_fail (ease != NULL, NULL);
  
    transition = g_slice_alloc (sizeof (GtkCssTransition));
    transition->parent.class = &GTK_CSS_TRANSITION_CLASS;
    transition->parent.ref_count = 1;
  
    transition->property = property;
    transition->start = _gtk_css_value_ref (start);
    transition->ease = _gtk_css_value_ref (ease);
    gtk_progress_tracker_start (&transition->tracker, duration_us, delay_us, 1.0);
    gtk_progress_tracker_advance_frame (&transition->tracker, timestamp);
    transition->finished = gtk_progress_tracker_get_state (&transition->tracker) == GTK_PROGRESS_STATE_AFTER;
  
    return (GtkStyleAnimation*)transition;
  }
  
  guint
  _gtk_css_transition_get_property (GtkCssTransition *transition)
  {
    return transition->property;
  }
  
  gboolean
  _gtk_css_transition_is_transition (GtkStyleAnimation  *animation)
  {
    return animation->class == &GTK_CSS_TRANSITION_CLASS;
  }
  