Node Editor: Link Drag Search Menu

This commit adds a search menu when links are dragged above empty
space. When releasing the drag, a menu displays all compatible
sockets with the source link. The "main" sockets (usually the first)
are weighted above other sockets in the search, so they appear first
when you type the name of the node.

A few special operators for creating a reroute or a group input node
are also added to the search.

Translation is started after choosing a node so it can be placed
quickly, since users would likely adjust the position after anyway.

A small "+" is displayed next to the cursor to give a hint about this.

Further improvements are possible after this first iteration:
 - Support custom node trees.
 - Better drawing of items in the search menu.
 - Potential tweaks to filtering of items, depending on user feedback.

Thanks to Juanfran Matheu for developing an initial patch.

Differential Revision: https://developer.blender.org/D8286

1 files changed, 54 insertions, 0 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_viewer.cc b/source/blender/nodes/geometry/nodes/node_geo_viewer.cc
index ad9737ac24b..18f2fa4cd36 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_viewer.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_viewer.cc
@@ -14,9 +14,16 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
+#include "BKE_context.h"
+
 #include "UI_interface.h"
 #include "UI_resources.h"
 
+#include "ED_node.h"
+#include "ED_spreadsheet.h"
+
+#include "NOD_socket_search_link.hh"
+
 #include "node_geometry_util.hh"
 
 namespace blender::nodes::node_geo_viewer_cc {
@@ -80,6 +87,52 @@ static void node_update(bNodeTree *ntree, bNode *node)
   }
 }
 
+static void node_gather_link_searches(GatherLinkSearchOpParams &params)
+{
+  auto set_active_fn = [](LinkSearchOpParams &params, bNode &viewer_node) {
+    /* Set this new viewer node active in spreadsheet editors. */
+    SpaceNode *snode = CTX_wm_space_node(&params.C);
+    Main *bmain = CTX_data_main(&params.C);
+    ED_node_set_active(bmain, snode, &params.node_tree, &viewer_node, nullptr);
+    ED_spreadsheet_context_paths_set_geometry_node(bmain, snode, &viewer_node);
+  };
+
+  const std::optional<CustomDataType> type = node_socket_to_custom_data_type(
+      params.other_socket());
+  if (params.in_out() == SOCK_OUT) {
+    /* The viewer node only has inputs. */
+    return;
+  }
+  if (params.other_socket().type == SOCK_GEOMETRY) {
+    params.add_item(IFACE_("Geometry"), [set_active_fn](LinkSearchOpParams &params) {
+      bNode &node = params.add_node("GeometryNodeViewer");
+      params.connect_available_socket(node, "Geometry");
+      set_active_fn(params, node);
+    });
+  }
+  if (type &&
+      ELEM(type, CD_PROP_FLOAT, CD_PROP_BOOL, CD_PROP_INT32, CD_PROP_FLOAT3, CD_PROP_COLOR)) {
+    params.add_item(IFACE_("Value"), [type, set_active_fn](LinkSearchOpParams &params) {
+      bNode &node = params.add_node("GeometryNodeViewer");
+      node_storage(node).data_type = *type;
+      params.update_and_connect_available_socket(node, "Value");
+
+      /* If the source node has a geometry socket, connect it to the new viewer node as well. */
+      LISTBASE_FOREACH (bNodeSocket *, socket, &params.node.outputs) {
+        if (socket->type == SOCK_GEOMETRY && !(socket->flag & (SOCK_UNAVAIL | SOCK_HIDDEN))) {
+          nodeAddLink(&params.node_tree,
+                      &params.node,
+                      socket,
+                      &node,
+                      static_cast<bNodeSocket *>(node.inputs.first));
+        }
+      }
+
+      set_active_fn(params, node);
+    });
+  }
+}
+
 }  // namespace blender::nodes::node_geo_viewer_cc
 
 void register_node_type_geo_viewer()
@@ -95,5 +148,6 @@ void register_node_type_geo_viewer()
   node_type_init(&ntype, file_ns::node_init);
   ntype.declare = file_ns::node_declare;
   ntype.draw_buttons_ex = file_ns::node_layout;
+  ntype.gather_link_search_ops = file_ns::node_gather_link_searches;
   nodeRegisterType(&ntype);
 }