cssvalue: Add _gtk_css_value_equal()

For now, we return FALSE for all default css values, so this is not very
useful.

I also think of this as an optimization equal, not a guaranteed equal,
because we don't even have a notion of what "equal" means.

For example, for background-repeat, "repeat, repeat" and "repeat"
are functionally equivalent. But the cssvalue has no idea that it's used
for background-repeat.
As a more complicated example, "repeat, no-repeat" and "repeat" are
equal to what one sees as long as there's only one image listed
background-image-source. But once you start transition'ing to an image
with 2 sources, it's different...

1 files changed, 8 insertions, 0 deletions

diff --git a/gtk/gtkcssinheritvalue.c b/gtk/gtkcssinheritvalue.c
index 99405bbb87..427f7ec09f 100644
--- a/gtk/gtkcssinheritvalue.c
+++ b/gtk/gtkcssinheritvalue.c
@@ -30,6 +30,13 @@ gtk_css_value_inherit_free (GtkCssValue *value)
   g_assert_not_reached ();
 }
 
+static gboolean
+gtk_css_value_inherit_equal (const GtkCssValue *value1,
+                             const GtkCssValue *value2)
+{
+  return TRUE;
+}
+
 static void
 gtk_css_value_inherit_print (const GtkCssValue *value,
                              GString           *string)
@@ -39,6 +46,7 @@ gtk_css_value_inherit_print (const GtkCssValue *value,
 
 static const GtkCssValueClass GTK_CSS_VALUE_INHERIT = {
   gtk_css_value_inherit_free,
+  gtk_css_value_inherit_equal,
   gtk_css_value_inherit_print
 };