cssimage: Add transition code for linear-gradient()

This ensures feature-parity with the CSS spec and the -gtk-gradient()
notation.

1 files changed, 75 insertions, 0 deletions

diff --git a/gtk/gtkcssimagelinear.c b/gtk/gtkcssimagelinear.c
index 39b6b3e781..bd80d5f835 100644
--- a/gtk/gtkcssimagelinear.c
+++ b/gtk/gtkcssimagelinear.c
@@ -451,6 +451,80 @@ gtk_css_image_linear_compute (GtkCssImage             *image,
   return GTK_CSS_IMAGE (copy);
 }
 
+static GtkCssImage *
+gtk_css_image_linear_transition (GtkCssImage *start_image,
+                                 GtkCssImage *end_image,
+                                 guint        property_id,
+                                 double       progress)
+{
+  GtkCssImageLinear *start, *end, *result;
+  guint i;
+
+  start = GTK_CSS_IMAGE_LINEAR (start_image);
+
+  if (end_image == NULL)
+
+  if (!GTK_IS_CSS_IMAGE_LINEAR (end_image))
+    return GTK_CSS_IMAGE_CLASS (_gtk_css_image_linear_parent_class)->transition (start_image, end_image, property_id, progress);
+
+  end = GTK_CSS_IMAGE_LINEAR (end_image);
+
+  if ((start->repeating != end->repeating)
+      || (start->stops->len != end->stops->len))
+    return GTK_CSS_IMAGE_CLASS (_gtk_css_image_linear_parent_class)->transition (start_image, end_image, property_id, progress);
+
+  result = g_object_new (GTK_TYPE_CSS_IMAGE_LINEAR, NULL);
+  result->repeating = start->repeating;
+
+  result->angle = _gtk_css_value_transition (start->angle, end->angle, property_id, progress);
+  if (result->angle == NULL)
+    goto fail;
+  
+  for (i = 0; i < start->stops->len; i++)
+    {
+      GtkCssImageLinearColorStop stop, *start_stop, *end_stop;
+
+      start_stop = &g_array_index (start->stops, GtkCssImageLinearColorStop, i);
+      end_stop = &g_array_index (end->stops, GtkCssImageLinearColorStop, i);
+
+      if ((start_stop->offset != NULL) != (end_stop->offset != NULL))
+        goto fail;
+
+      if (start_stop->offset == NULL)
+        {
+          stop.offset = NULL;
+        }
+      else
+        {
+          stop.offset = _gtk_css_value_transition (start_stop->offset,
+                                                   end_stop->offset,
+                                                   property_id,
+                                                   progress);
+          if (stop.offset == NULL)
+            goto fail;
+        }
+
+      stop.color = _gtk_css_value_transition (start_stop->color,
+                                              end_stop->color,
+                                              property_id,
+                                              progress);
+      if (stop.color == NULL)
+        {
+          if (stop.offset)
+            _gtk_css_value_unref (stop.offset);
+          goto fail;
+        }
+
+      g_array_append_val (result->stops, stop);
+    }
+
+  return GTK_CSS_IMAGE (result);
+
+fail:
+  g_object_unref (result);
+  return GTK_CSS_IMAGE_CLASS (_gtk_css_image_linear_parent_class)->transition (start_image, end_image, property_id, progress);
+}
+
 static void
 gtk_css_image_linear_dispose (GObject *object)
 {
@@ -481,6 +555,7 @@ _gtk_css_image_linear_class_init (GtkCssImageLinearClass *klass)
   image_class->parse = gtk_css_image_linear_parse;
   image_class->print = gtk_css_image_linear_print;
   image_class->compute = gtk_css_image_linear_compute;
+  image_class->transition = gtk_css_image_linear_transition;
 
   object_class->dispose = gtk_css_image_linear_dispose;
 }