theming: Introduce image size fallback mode

This changes image size handling a little bit. An optional <fallback size="xxx" />
tag tells the generator to use different image size when an image for the current
image size has not been supplied from the album XML file.

This is effectively used for the legacy <nofullsize> tag fallback. More generally
this is useful for templates showing additional image sizes. Also saves space as
images not having the custom size supplied are not generated from the source image.

1 files changed, 28 insertions, 3 deletions

diff --git a/src/setup.c b/src/setup.c
index 9cdf7d5..f0a6f3d 100644
--- a/src/setup.c
+++ b/src/setup.c
@@ -233,8 +233,8 @@ parse_design_setup_xml (const gchar *filename)
     image_size->quality = xml_file_get_node_attribute_long_with_default (xml, s, "value", -1);
     g_free (s);
 
-    s = g_strdup_printf ("/design_setup/image_sizes/size[%d]/no_resize", i + 1);
-    image_size->no_resize = xml_file_get_node_present (xml, s);
+    s = g_strdup_printf ("/design_setup/image_sizes/size[%d]/fallback", i + 1);
+    image_size->fallback_size = xml_file_get_node_attribute (xml, s, "size");
     g_free (s);
   }
 
@@ -434,8 +434,10 @@ gboolean
 validate_design_setup (TGallerySetup *setup)
 {
   GList *l;
-  TImageSize *image_size;
+  TImageSize *image_size, *isi;
   TGalleryDesignTheme *theme;
+  GHashTable *fallback_history;
+  gboolean res;
 
   /*  check for version match  */
   if (! SETUP_IS_NATIVE (setup->design)) {
@@ -460,6 +462,28 @@ validate_design_setup (TGallerySetup *setup)
       fprintf (stderr, "design validation warning: image size %s defined with zero sized element\n", image_size->name);
       continue;
     }
+    if (image_size->fallback_size != NULL && lookup_image_size_for_name (setup, image_size->fallback_size) == NULL) {
+      fprintf (stderr, "design validation error: specified \"%s\" fallback image size not found\n", image_size->fallback_size);
+      return FALSE;
+    }
+    if (image_size->fallback_size != NULL) {
+      fallback_history = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
+      isi = image_size;
+      res = TRUE;
+      while (isi != NULL) {
+        if (g_hash_table_lookup (fallback_history, isi->name)) {
+          res = FALSE;
+          break;
+        }
+        g_hash_table_insert (fallback_history, g_strdup (isi->name), (gpointer) 0x1);
+        isi = lookup_image_size_for_name (setup, isi->fallback_size);
+      }
+      g_hash_table_unref (fallback_history);
+      if (! res) {
+        fprintf (stderr, "design validation error: the fallback path for the \"%s\" image size leads to an endless loop\n", image_size->name);
+        return FALSE;
+      }
+    }
   }
 
   /*  validate themes  */
@@ -577,6 +601,7 @@ free_image_size_data (TImageSize *image_size)
   if (image_size) {
     g_free (image_size->name);
     g_free (image_size->tagname);
+    g_free (image_size->fallback_size);
     g_free (image_size);
   }
 }