Geometry Nodes: Attribute search drop-down

This commit adds a search for existing attributes when you click
on an attribute field. This is useful because otherwise you have
to remember which attributes should be available at each node in
the tree.

The fundamental complication is that this information is not
accessible statically. So the search data is only a cache from
the previous node tree evaluation. The information is added
with `BKE_nodetree_attribute_hint_add`, currently for every
input geometry socket for a single node.

This is only an initial implementation, and later versions will
expose the data type and domain of the attributes.

Differential Revision: https://developer.blender.org/D10519

source/blender/editors/space_node/CMakeLists.txt

@@ -42,6 +42,7 @@ set(SRC
   node_buttons.c
   node_draw.cc
   node_edit.c
+  node_geometry_attribute_search.cc
   node_gizmo.c
   node_group.c
   node_ops.c

source/blender/editors/space_node/drawnode.c

@@ -3389,7 +3389,15 @@ static void std_node_socket_draw(
     case SOCK_STRING: {
       uiLayout *row = uiLayoutSplit(layout, 0.5f, false);
       uiItemL(row, text, 0);
-      uiItemR(row, ptr, "default_value", DEFAULT_FLAGS, "", 0);
+
+      const bNodeTree *node_tree = (const bNodeTree *)node_ptr->owner_id;
+      if (node_tree->type == NTREE_GEOMETRY) {
+        node_geometry_add_attribute_search_button(node_tree, node, ptr, row);
+      }
+      else {
+        uiItemR(row, ptr, "default_value", DEFAULT_FLAGS, "", 0);
+      }
+
       break;
     }
     case SOCK_OBJECT: {

source/blender/editors/space_node/node_geometry_attribute_search.cc

@@ -0,0 +1,151 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "BLI_index_range.hh"
+#include "BLI_listbase.h"
+#include "BLI_map.hh"
+#include "BLI_set.hh"
+#include "BLI_string_ref.hh"
+#include "BLI_string_search.h"
+
+#include "DNA_modifier_types.h"
+#include "DNA_node_types.h"
+#include "DNA_object_types.h"
+#include "DNA_space_types.h"
+
+#include "BKE_context.h"
+#include "BKE_node_ui_storage.hh"
+#include "BKE_object.h"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "node_intern.h"
+
+using blender::IndexRange;
+using blender::Map;
+using blender::Set;
+using blender::StringRef;
+
+struct AttributeSearchData {
+  const bNodeTree &node_tree;
+  const bNode &node;
+
+  uiBut *search_button;
+
+  /* Used to keep track of a button pointer over multiple redraws. Since the UI code
+   * may reallocate the button, without this we might end up with a dangling pointer. */
+  uiButStore *button_store;
+  uiBlock *button_store_block;
+};
+
+static void attribute_search_update_fn(
+    const bContext *C, void *arg, const char *str, uiSearchItems *items, const bool is_first)
+{
+  AttributeSearchData *data = static_cast<AttributeSearchData *>(arg);
+  const NodeUIStorage *ui_storage = BKE_node_tree_ui_storage_get_from_context(
+      C, data->node_tree, data->node);
+  if (ui_storage == nullptr) {
+    return;
+  }
+
+  const Set<std::string> &attribute_name_hints = ui_storage->attribute_name_hints;
+
+  if (str[0] != '\0' && !attribute_name_hints.contains_as(StringRef(str))) {
+    /* Any string may be valid, so add the current search string with the hints. */
+    UI_search_item_add(items, str, (void *)str, ICON_ADD, 0, 0);
+  }
+
+  /* Skip the filter when the menu is first opened, so all of the items are visible. */
+  if (is_first) {
+    for (const std::string &attribute_name : attribute_name_hints) {
+      /* Just use the pointer to the name string as the search data,
+       * since it's not used anyway but we need a pointer. */
+      UI_search_item_add(items, attribute_name.c_str(), (void *)&attribute_name, ICON_NONE, 0, 0);
+    }
+    return;
+  }
+
+  StringSearch *search = BLI_string_search_new();
+  for (const std::string &attribute_name : attribute_name_hints) {
+    BLI_string_search_add(search, attribute_name.c_str(), (void *)&attribute_name);
+  }
+
+  std::string **filtered_items;
+  const int filtered_amount = BLI_string_search_query(search, str, (void ***)&filtered_items);
+
+  for (const int i : IndexRange(filtered_amount)) {
+    std::string *item = filtered_items[i];
+    if (!UI_search_item_add(items, item->c_str(), item, ICON_NONE, 0, 0)) {
+      break;
+    }
+  }
+
+  MEM_freeN(filtered_items);
+  BLI_string_search_free(search);
+}
+
+static void attribute_search_free_fn(void *arg)
+{
+  AttributeSearchData *data = static_cast<AttributeSearchData *>(arg);
+
+  UI_butstore_free(data->button_store_block, data->button_store);
+  delete data;
+}
+
+void node_geometry_add_attribute_search_button(const bNodeTree *node_tree,
+                                               const bNode *node,
+                                               PointerRNA *socket_ptr,
+                                               uiLayout *layout)
+{
+  uiBlock *block = uiLayoutGetBlock(layout);
+  uiBut *but = uiDefIconTextButR(block,
+                                 UI_BTYPE_SEARCH_MENU,
+                                 0,
+                                 ICON_NONE,
+                                 "",
+                                 0,
+                                 0,
+                                 10 * UI_UNIT_X, /* Dummy value, replaced by layout system. */
+                                 UI_UNIT_Y,
+                                 socket_ptr,
+                                 "default_value",
+                                 0,
+                                 0.0f,
+                                 0.0f,
+                                 0.0f,
+                                 0.0f,
+                                 "");
+
+  AttributeSearchData *data = new AttributeSearchData{
+      *node_tree,
+      *node,
+      but,
+      UI_butstore_create(block),
+      block,
+  };
+
+  UI_butstore_register(data->button_store, &data->search_button);
+
+  UI_but_func_search_set_results_are_suggestions(but, true);
+  UI_but_func_search_set(but,
+                         nullptr,
+                         attribute_search_update_fn,
+                         static_cast<void *>(data),
+                         attribute_search_free_fn,
+                         nullptr,
+                         nullptr);
+}

source/blender/editors/space_node/node_intern.h

@@ -38,9 +38,11 @@ struct bContext;
 struct bNode;
 struct bNodeLink;
 struct bNodeSocket;
+struct uiBut;
 struct wmGizmoGroupType;
 struct wmKeyConfig;
 struct wmWindow;
+struct uiBlock;
 
 #ifdef __cplusplus
 extern "C" {
@@ -289,6 +291,12 @@ void NODE_GGT_backdrop_corner_pin(struct wmGizmoGroupType *gzgt);
 void NODE_OT_cryptomatte_layer_add(struct wmOperatorType *ot);
 void NODE_OT_cryptomatte_layer_remove(struct wmOperatorType *ot);
 
+/* node_geometry_attribute_search.cc */
+void node_geometry_add_attribute_search_button(const struct bNodeTree *node_tree,
+                                               const struct bNode *node,
+                                               struct PointerRNA *socket_ptr,
+                                               struct uiLayout *layout);
+
 extern const char *node_context_dir[];
 
 /* XXXXXX */