[gnome-shell/wip/resource-scale: 2/7] StWidget: Introduce widget resource scale

[Marco Trevisan <marcotrevi src gnome org>]

commit 91e913ce1aa44be076928f1b8025a5c8cfa73519
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu May 11 12:30:04 2017 +0800

    StWidget: Introduce widget resource scale
    
    This commit makes StWidget manage the scale of which its associated
    resources should be multiplied with. The resource scale is calculated
    by clutter, and is retrieved by clutter_actor_get_resource_scale(). Due
    to the resource scale not always being available, the getter may fail,
    and the actual widget that draws the content will have to deal with
    this situation.
    
    As the resource scale depends on where on the stage the widget is drawn,
    the resource scale will in general be available once the widget is
    mapped.

 src/st/st-widget.c |   98 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/st/st-widget.h |    3 ++
 2 files changed, 99 insertions(+), 2 deletions(-)
---
diff --git a/src/st/st-widget.c b/src/st/st-widget.c
index db984ac..5817411 100644
--- a/src/st/st-widget.c
+++ b/src/st/st-widget.c
@@ -70,6 +70,9 @@ struct _StWidgetPrivate
   guint track_hover : 1;
   guint hover : 1;
   guint can_focus : 1;
+  guint is_resource_scale_valid : 1;
+
+  float resource_scale;
 
   gulong texture_file_changed_id;
 
@@ -121,6 +124,7 @@ enum
 {
   STYLE_CHANGED,
   POPUP_MENU,
+  RESOURCE_SCALE_CHANGED,
 
   LAST_SIGNAL
 };
@@ -140,6 +144,8 @@ static gboolean st_widget_real_navigate_focus (StWidget         *widget,
 
 static AtkObject * st_widget_get_accessible (ClutterActor *actor);
 
+static void st_widget_sync_resource_scale (StWidget *widget);
+
 static void
 st_widget_set_property (GObject      *gobject,
                         guint         prop_id,
@@ -408,6 +414,7 @@ st_widget_allocate (ClutterActor          *actor,
                     const ClutterActorBox *box,
                     ClutterAllocationFlags flags)
 {
+  StWidgetPrivate *priv = st_widget_get_instance_private (ST_WIDGET (actor));
   StThemeNode *theme_node = st_widget_get_theme_node (ST_WIDGET (actor));
   ClutterActorBox content_box;
 
@@ -427,6 +434,9 @@ st_widget_allocate (ClutterActor          *actor,
                                    CLUTTER_CONTAINER (actor),
                                    &content_box,
                                    flags);
+
+  priv->is_resource_scale_valid = FALSE;
+  st_widget_sync_resource_scale (ST_WIDGET (actor));
 }
 
 /**
@@ -476,6 +486,7 @@ static void
 st_widget_parent_set (ClutterActor *widget,
                       ClutterActor *old_parent)
 {
+  StWidget *self = ST_WIDGET (widget);
   ClutterActorClass *parent_class;
   ClutterActor *new_parent;
 
@@ -487,7 +498,22 @@ st_widget_parent_set (ClutterActor *widget,
 
   /* don't send the style changed signal if we no longer have a parent actor */
   if (new_parent)
-    st_widget_style_changed (ST_WIDGET (widget));
+    {
+      st_widget_style_changed (self);
+      st_widget_sync_resource_scale (self);
+    }
+}
+
+static void
+st_widget_realize (ClutterActor *actor)
+{
+  ClutterActorClass *actor_class =
+    CLUTTER_ACTOR_CLASS (st_widget_parent_class);
+
+  if (actor_class->realize)
+    actor_class->realize (actor);
+
+  st_widget_sync_resource_scale (ST_WIDGET (actor));
 }
 
 static void
@@ -498,6 +524,7 @@ st_widget_map (ClutterActor *actor)
   CLUTTER_ACTOR_CLASS (st_widget_parent_class)->map (actor);
 
   st_widget_ensure_style (self);
+  st_widget_sync_resource_scale (self);
 }
 
 static void
@@ -531,7 +558,7 @@ notify_children_of_style_change (ClutterActor *self)
 static void
 st_widget_real_style_changed (StWidget *self)
 {
-  clutter_actor_queue_redraw ((ClutterActor *) self);
+  clutter_actor_queue_relayout ((ClutterActor *) self);
   notify_children_of_style_change ((ClutterActor *) self);
 }
 
@@ -857,6 +884,7 @@ st_widget_class_init (StWidgetClass *klass)
   actor_class->paint = st_widget_paint;
   actor_class->get_paint_volume = st_widget_get_paint_volume;
   actor_class->parent_set = st_widget_parent_set;
+  actor_class->realize = st_widget_realize;
   actor_class->map = st_widget_map;
   actor_class->unmap = st_widget_unmap;
 
@@ -1044,6 +1072,21 @@ st_widget_class_init (StWidgetClass *klass)
                   G_STRUCT_OFFSET (StWidgetClass, popup_menu),
                   NULL, NULL, NULL,
                   G_TYPE_NONE, 0);
+
+  /**
+   * StWidget::resource-scale-changed:
+   * @widget: the #StWidget
+   *
+   * Emitted when the paint scale that the widget will be painted as
+   * changed.
+   */
+  signals[RESOURCE_SCALE_CHANGED] =
+    g_signal_new ("resource-scale-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (StWidgetClass, resource_scale_changed),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
 }
 
 /**
@@ -1473,6 +1516,57 @@ st_widget_get_style (StWidget *actor)
   return ST_WIDGET_PRIVATE (actor)->inline_style;
 }
 
+static gboolean
+st_widget_update_resource_scale (StWidget *widget)
+{
+  StWidgetPrivate *priv = st_widget_get_instance_private (widget);
+  float resource_scale;
+  float old_resource_scale;
+
+  g_return_val_if_fail (!priv->is_resource_scale_valid, FALSE);
+
+  if (!clutter_actor_get_resource_scale (CLUTTER_ACTOR (widget), &resource_scale))
+    return FALSE;
+
+  old_resource_scale = priv->resource_scale;
+  priv->resource_scale = resource_scale;
+  priv->is_resource_scale_valid = TRUE;
+
+  return old_resource_scale != resource_scale;
+}
+
+static void
+st_widget_sync_resource_scale (StWidget *widget)
+{
+  StWidgetPrivate *priv = st_widget_get_instance_private (widget);
+
+  if (priv->is_resource_scale_valid)
+    return;
+
+  if (st_widget_update_resource_scale (widget))
+    g_signal_emit (widget, signals[RESOURCE_SCALE_CHANGED], 0);
+}
+
+gboolean
+st_widget_get_resource_scale (StWidget *widget,
+                              float    *resource_scale)
+{
+  StWidgetPrivate *priv = st_widget_get_instance_private (widget);
+
+  if (!priv->is_resource_scale_valid)
+    st_widget_update_resource_scale (widget);
+
+  if (priv->is_resource_scale_valid)
+    {
+      *resource_scale = priv->resource_scale;
+      return TRUE;
+    }
+  else
+    {
+      return FALSE;
+    }
+}
+
 static void
 st_widget_name_notify (StWidget   *widget,
                        GParamSpec *pspec,
diff --git a/src/st/st-widget.h b/src/st/st-widget.h
index 4f351ea..192f061 100644
--- a/src/st/st-widget.h
+++ b/src/st/st-widget.h
@@ -53,6 +53,7 @@ struct _StWidgetClass
   /* signals */
   void     (* style_changed)       (StWidget         *self);
   void     (* popup_menu)          (StWidget         *self);
+  void     (* resource_scale_changed) (StWidget         *self);
 
   /* vfuncs */
 
@@ -127,6 +128,8 @@ StThemeNode *         st_widget_peek_theme_node           (StWidget        *widg
 
 GList *               st_widget_get_focus_chain           (StWidget        *widget);
 void                  st_widget_paint_background          (StWidget        *widget);
+gboolean              st_widget_get_resource_scale        (StWidget        *widget,
+                                                           float           *resource_scale);
 
 /* debug methods */
 char  *st_describe_actor       (ClutterActor *actor);