Nodes: Add a callback to check for valid socket type

This adds a callback to bNodeTreeType to check which socket types are
valid for the tree type. Function has been implemented for the normal
tree types, and can be implemented for custom node trees with python,
by adding a `classmethod` to the tree. However, only builtin socket
types are supported.

This is relevant for T87049, but it also has the advantage that it is
now clear which node trees support which sockets. Previously this
was assumed to be known by all developers.

Differential Revision: https://developer.blender.org/D10938

1 files changed, 36 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index a738084dbcd..3b81b591f6d 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -971,6 +971,32 @@ static void rna_NodeTree_get_from_context(
   RNA_parameter_list_free(&list);
 }
 
+static bool rna_NodeTree_valid_socket_type(eNodeSocketDatatype socket_type,
+                                           bNodeTreeType *ntreetype)
+{
+  extern FunctionRNA rna_NodeTree_valid_socket_type_func;
+
+  PointerRNA ptr;
+  ParameterList list;
+  FunctionRNA *func;
+  void *ret;
+  bool valid;
+
+  RNA_pointer_create(NULL, ntreetype->rna_ext.srna, NULL, &ptr); /* dummy */
+  func = &rna_NodeTree_valid_socket_type_func;
+
+  RNA_parameter_list_create(&list, &ptr, func);
+  RNA_parameter_set_lookup(&list, "type", &socket_type);
+  ntreetype->rna_ext.call(NULL, &ptr, func, &list);
+
+  RNA_parameter_get_lookup(&list, "valid", &ret);
+  valid = *(bool *)ret;
+
+  RNA_parameter_list_free(&list);
+
+  return valid;
+}
+
 static void rna_NodeTree_unregister(Main *UNUSED(bmain), StructRNA *type)
 {
   bNodeTreeType *nt = RNA_struct_blender_type_get(type);
@@ -999,7 +1025,7 @@ static StructRNA *rna_NodeTree_register(Main *bmain,
   bNodeTreeType *nt, dummynt;
   bNodeTree dummyntree;
   PointerRNA dummyptr;
-  int have_function[3];
+  int have_function[4];
 
   /* setup dummy tree & tree type to store static properties in */
   memset(&dummynt, 0, sizeof(bNodeTreeType));
@@ -1045,6 +1071,7 @@ static StructRNA *rna_NodeTree_register(Main *bmain,
   nt->poll = (have_function[0]) ? rna_NodeTree_poll : NULL;
   nt->update = (have_function[1]) ? rna_NodeTree_update_reg : NULL;
   nt->get_from_context = (have_function[2]) ? rna_NodeTree_get_from_context : NULL;
+  nt->valid_socket_type = (have_function[3]) ? rna_NodeTree_valid_socket_type : NULL;
 
   ntreeTypeAdd(nt);
 
@@ -11414,6 +11441,14 @@ static void rna_def_nodetree(BlenderRNA *brna)
   parm = RNA_def_pointer(
       func, "result_3", "ID", "From ID", "Original ID data-block selected from the context");
   RNA_def_function_output(func, parm);
+
+  /* Check for support of a socket type. */
+  func = RNA_def_function(srna, "valid_socket_type", NULL);
+  RNA_def_function_ui_description(func, "Check if the socket type is valid for the node tree");
+  RNA_def_function_flag(func, FUNC_NO_SELF | FUNC_REGISTER_OPTIONAL);
+  parm = RNA_def_enum(func, "type", node_socket_type_items, 0, "", "");
+  RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
+  RNA_def_function_return(func, RNA_def_boolean(func, "valid", false, "", ""));
 }
 
 static void rna_def_composite_nodetree(BlenderRNA *brna)