css: Introduce dependencies for value computations

When values are computed, they might depend on various other values and
we need to track this so we can update the values when those other
values change. This is the first step in making that happen.

This patch does not do any dependency tracking at all, instead it uses
GTK_CSS_DEPENDS_ON_EVERYTHING as a sort of FIXME.

1 files changed, 15 insertions, 5 deletions

diff --git a/gtk/gtkcssvalue.c b/gtk/gtkcssvalue.c
index 5d5d39227f..e057f90b50 100644
--- a/gtk/gtkcssvalue.c
+++ b/gtk/gtkcssvalue.c
@@ -66,6 +66,9 @@ _gtk_css_value_unref (GtkCssValue *value)
  * @value: the value to compute from
  * @property_id: the ID of the property to compute
  * @context: the context to use for resolving
+ * @dependencies: (out) (allow-none): Set to the dependencies of the
+ *     computed values that indicate when this value needs to be
+ *     recomputed and how.
  *
  * Converts the specified @value into the computed value for the CSS
  * property given by @property_id using the information in @context.
@@ -73,17 +76,24 @@ _gtk_css_value_unref (GtkCssValue *value)
  * <ulink url="http://www.w3.org/TR/css3-cascade/#computed>
  * the CSS documentation</ulink>.
  *
- * Returns: the comptued value
+ * Returns: the computed value
  **/
 GtkCssValue *
-_gtk_css_value_compute (GtkCssValue     *value,
-                        guint            property_id,
-                        GtkStyleContext *context)
+_gtk_css_value_compute (GtkCssValue        *value,
+                        guint               property_id,
+                        GtkStyleContext    *context,
+                        GtkCssDependencies *dependencies)
 {
+  GtkCssDependencies fallback;
+
   g_return_val_if_fail (value != NULL, NULL);
   g_return_val_if_fail (GTK_IS_STYLE_CONTEXT (context), NULL);
 
-  return value->class->compute (value, property_id, context);
+  if (dependencies == NULL)
+    dependencies = &fallback;
+  *dependencies = 0;
+
+  return value->class->compute (value, property_id, context, dependencies);
 }
 
 gboolean