cssimage: Add gtk_css_image_is_invalid()

Use that instead of hacks to guess when an image is considered invalid
according to https://drafts.csswg.org/css-images-4/#invalid-image

Also add a GtkCssImageInvalid that implements the behavior of invalid
images according to the CSS spec so thjat image implementations can
refer to that image.

1 files changed, 19 insertions, 0 deletions

diff --git a/gtk/gtkcssimage.c b/gtk/gtkcssimage.c
index 10cdc73ce5..c61c3ee4a5 100644
--- a/gtk/gtkcssimage.c
+++ b/gtk/gtkcssimage.c
@@ -97,6 +97,12 @@ gtk_css_image_real_transition (GtkCssImage *start,
 }
 
 static gboolean
+gtk_css_image_real_is_invalid (GtkCssImage *image)
+{
+  return FALSE;
+}
+
+static gboolean
 gtk_css_image_real_is_dynamic (GtkCssImage *image)
 {
   return FALSE;
@@ -118,6 +124,7 @@ _gtk_css_image_class_init (GtkCssImageClass *klass)
   klass->compute = gtk_css_image_real_compute;
   klass->equal = gtk_css_image_real_equal;
   klass->transition = gtk_css_image_real_transition;
+  klass->is_invalid = gtk_css_image_real_is_invalid;
   klass->is_dynamic = gtk_css_image_real_is_dynamic;
   klass->get_dynamic_image = gtk_css_image_real_get_dynamic_image;
 }
@@ -280,6 +287,18 @@ gtk_css_image_snapshot (GtkCssImage *image,
 }
 
 gboolean
+gtk_css_image_is_invalid (GtkCssImage *image)
+{
+  GtkCssImageClass *klass;
+
+  g_return_val_if_fail (GTK_IS_CSS_IMAGE (image), FALSE);
+
+  klass = GTK_CSS_IMAGE_GET_CLASS (image);
+
+  return klass->is_invalid (image);
+}
+
+gboolean
 gtk_css_image_is_dynamic (GtkCssImage *image)
 {
   GtkCssImageClass *klass;