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, 3 insertions, 0 deletions

diff --git a/source/blender/nodes/composite/node_composite_util.cc b/source/blender/nodes/composite/node_composite_util.cc
index 9ea98d2a867..1262dfad11f 100644
--- a/source/blender/nodes/composite/node_composite_util.cc
+++ b/source/blender/nodes/composite/node_composite_util.cc
@@ -21,6 +21,8 @@
  * \ingroup nodes
  */
 
+#include "NOD_socket_search_link.hh"
+
 #include "node_composite_util.hh"
 
 bool cmp_node_poll_default(bNodeType *UNUSED(ntype),
@@ -52,4 +54,5 @@ void cmp_node_type_base(bNodeType *ntype, int type, const char *name, short ncla
   ntype->poll = cmp_node_poll_default;
   ntype->updatefunc = cmp_node_update_default;
   ntype->insert_link = node_insert_link_default;
+  ntype->gather_link_search_ops = blender::nodes::search_link_ops_for_basic_node;
 }