# UNDF: UNDF-2026-000000797
# UNDF: (leave blank)
# darktable-0003: map view clustering g_list_find(sel_imgs) inside O(I*J) loop
#
# In src/views/map.c, the map clustering code iterates over all images (i-loop)
# and for each cluster, iterates again over all images (j-loop). Inside the
# j-loop, g_list_find(sel_imgs, GINT_TO_POINTER(p[j].imgid)) performs a linear
# scan of the selected-images list (length S). Total complexity: O(I*J*S)
# which for 5000 map images with 500 selected is O(5000*5000*500) = 12.5
# billion pointer comparisons.
#
# The outer i-loop also calls g_list_find(sel_imgs, ...) for NOISE points
# and cluster heads — each O(S), contributing O(I*S) additional.
#
# Fix: build a GHashTable from sel_imgs before the loop, replace g_list_find
# with g_hash_table_contains for O(1) lookup.
#
# Severity: HIGH — map view is redrawn on every pan/zoom with the full image
# collection; O(I²×S) collapses to O(I²+S).
--- a/src/views/map.c
+++ b/src/views/map.c
@@ -1506,6 +1506,12 @@
       gboolean *processed = calloc(num_clusters+1,sizeof(gboolean));
       GList *sel_imgs = dt_act_on_get_images(FALSE, FALSE, FALSE);
+
+      // Build hash set for O(1) selection membership test
+      GHashTable *sel_set = g_hash_table_new(g_direct_hash, g_direct_equal);
+      for(GList *si = sel_imgs; si; si = g_list_next(si))
+        g_hash_table_add(sel_set, si->data);
+
       int group = -1;
       for(i = 0; i< img_count; i++)
       {
@@ -1523,8 +1529,7 @@
             if(sel_imgs)
-              entry->selected_in_group = g_list_find((GList *)sel_imgs,
-                                                     GINT_TO_POINTER(entry->imgid))
-                                         ? TRUE : FALSE;
+              entry->selected_in_group =
+                g_hash_table_contains(sel_set, GINT_TO_POINTER(entry->imgid));
             lib->images = g_slist_prepend(lib->images, entry);
@@ -1540,8 +1545,7 @@
-            entry->selected_in_group = (sel_imgs && g_list_find((GList *)sel_imgs,
-                                                                GINT_TO_POINTER(p[i].imgid)))
-                                       ? TRUE : FALSE;
+            entry->selected_in_group = sel_imgs
+              && g_hash_table_contains(sel_set, GINT_TO_POINTER(p[i].imgid));
@@ -1557,7 +1561,7 @@
                 if(sel_imgs && !entry->selected_in_group)
                 {
-                  if(g_list_find((GList *)sel_imgs, GINT_TO_POINTER(p[j].imgid)))
+                  if(g_hash_table_contains(sel_set, GINT_TO_POINTER(p[j].imgid)))
                     entry->selected_in_group = TRUE;
                 }
       }
       free(processed);
+      g_hash_table_destroy(sel_set);
       g_list_free(sel_imgs);