UI support for showing candidates for string properties

Currently strings are used for cases where a list of identifiers would
be useful to show.

Add support for string properties to reference a callback to populate
candidates to show when editing a string. The user isn't prevented from
typing in text not found in this list, it's just useful as a reference.

Support for expanding the following strings has been added:

- Operator, menu & panel identifiers in the keymap editor.
- WM operators that reference data-paths expand using the
  Python-consoles auto-complete functionality.
- Names of keying sets for insert/delete keyframe operators.

Details:

- `bpy.props.StringProperty` takes an option `search` callback.

- A new string callback has been added, set via
  `RNA_def_property_string_search_func` or
  `RNA_def_property_string_search_func_runtime`.

- Addresses usability issue highlighted by T89560,
  where setting keying set identifiers as strings isn't practical.

- Showing additional right-aligned text in the search results is
  supported but disabled by default as the text is too cramped in most
  string search popups where the feature would make sense. It could be
  enabled as part of other layout tweaks.

Reviewed By: brecht

Ref D14986

5 files changed, 116 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index c3ca57b38bf..400944d60d4 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -1039,6 +1039,38 @@ static void rna_clamp_value(FILE *f, PropertyRNA *prop, int array)
   }
 }
 
+static char *rna_def_property_search_func(FILE *f,
+                                          StructRNA *srna,
+                                          PropertyRNA *prop,
+                                          PropertyDefRNA *UNUSED(dp),
+                                          const char *manualfunc)
+{
+  char *func;
+
+  if (prop->flag & PROP_IDPROPERTY && manualfunc == NULL) {
+    return NULL;
+  }
+  if (!manualfunc) {
+    return NULL;
+  }
+
+  func = rna_alloc_function_name(srna->identifier, rna_safe_id(prop->identifier), "search");
+
+  fprintf(f,
+          "void %s("
+          "const bContext *C, "
+          "PointerRNA *ptr, "
+          "PropertyRNA *prop, "
+          "const char *edit_text, "
+          "StringPropertySearchVisitFunc visit_fn, "
+          "void *visit_user_data)\n",
+          func);
+  fprintf(f, "{\n");
+  fprintf(f, "\n    %s(C, ptr, prop, edit_text, visit_fn, visit_user_data);\n", manualfunc);
+  fprintf(f, "}\n\n");
+  return func;
+}
+
 static char *rna_def_property_set_func(
     FILE *f, StructRNA *srna, PropertyRNA *prop, PropertyDefRNA *dp, const char *manualfunc)
 {
@@ -1895,6 +1927,8 @@ static void rna_def_property_funcs(FILE *f, StructRNA *srna, PropertyDefRNA *dp)
       sprop->length = (void *)rna_def_property_length_func(
           f, srna, prop, dp, (const char *)sprop->length);
       sprop->set = (void *)rna_def_property_set_func(f, srna, prop, dp, (const char *)sprop->set);
+      sprop->search = (void *)rna_def_property_search_func(
+          f, srna, prop, dp, (const char *)sprop->search);
       break;
     }
     case PROP_POINTER: {
@@ -4081,13 +4115,15 @@ static void rna_generate_property(FILE *f, StructRNA *srna, const char *nest, Pr
     case PROP_STRING: {
       StringPropertyRNA *sprop = (StringPropertyRNA *)prop;
       fprintf(f,
-              "\t%s, %s, %s, %s, %s, %s, %d, ",
+              "\t%s, %s, %s, %s, %s, %s, %s, %d, %d, ",
               rna_function_string(sprop->get),
               rna_function_string(sprop->length),
               rna_function_string(sprop->set),
               rna_function_string(sprop->get_ex),
               rna_function_string(sprop->length_ex),
               rna_function_string(sprop->set_ex),
+              rna_function_string(sprop->search),
+              (int)sprop->search_flag,
               sprop->maxlength);
       rna_print_c_string(f, sprop->defaultvalue);
       fprintf(f, "\n");
diff --git a/source/blender/makesrna/intern/rna_access.c b/source/blender/makesrna/intern/rna_access.c
index ccb7e1c69bc..c8cb0b7ffb8 100644
--- a/source/blender/makesrna/intern/rna_access.c
+++ b/source/blender/makesrna/intern/rna_access.c
@@ -3369,6 +3369,34 @@ int RNA_property_string_default_length(PointerRNA *UNUSED(ptr), PropertyRNA *pro
   return strlen(sprop->defaultvalue);
 }
 
+eStringPropertySearchFlag RNA_property_string_search_flag(PropertyRNA *prop)
+{
+  StringPropertyRNA *sprop = (StringPropertyRNA *)rna_ensure_property(prop);
+  if (prop->magic != RNA_MAGIC) {
+    return false;
+  }
+  BLI_assert(RNA_property_type(prop) == PROP_STRING);
+  if (sprop->search) {
+    BLI_assert(sprop->search_flag & PROP_STRING_SEARCH_SUPPORTED);
+  }
+  else {
+    BLI_assert(sprop->search_flag == 0);
+  }
+  return sprop->search_flag;
+}
+
+void RNA_property_string_search(const bContext *C,
+                                PointerRNA *ptr,
+                                PropertyRNA *prop,
+                                const char *edit_text,
+                                StringPropertySearchVisitFunc visit_fn,
+                                void *visit_user_data)
+{
+  BLI_assert(RNA_property_string_search_flag(prop) & PROP_STRING_SEARCH_SUPPORTED);
+  StringPropertyRNA *sprop = (StringPropertyRNA *)rna_ensure_property(prop);
+  sprop->search(C, ptr, prop, edit_text, visit_fn, visit_user_data);
+}
+
 int RNA_property_enum_get(PointerRNA *ptr, PropertyRNA *prop)
 {
   EnumPropertyRNA *eprop = (EnumPropertyRNA *)prop;
diff --git a/source/blender/makesrna/intern/rna_define.c b/source/blender/makesrna/intern/rna_define.c
index 1e950b883ab..dfb551fcb05 100644
--- a/source/blender/makesrna/intern/rna_define.c
+++ b/source/blender/makesrna/intern/rna_define.c
@@ -3316,6 +3316,33 @@ void RNA_def_property_string_funcs(PropertyRNA *prop,
   }
 }
 
+void RNA_def_property_string_search_func(PropertyRNA *prop,
+                                         const char *search,
+                                         const eStringPropertySearchFlag search_flag)
+{
+  StructRNA *srna = DefRNA.laststruct;
+
+  if (!DefRNA.preprocess) {
+    CLOG_ERROR(&LOG, "only during preprocessing.");
+    return;
+  }
+
+  switch (prop->type) {
+    case PROP_STRING: {
+      StringPropertyRNA *sprop = (StringPropertyRNA *)prop;
+      sprop->search = (StringPropertySearchFunc)search;
+      if (search != NULL) {
+        sprop->search_flag = search_flag | PROP_STRING_SEARCH_SUPPORTED;
+      }
+      break;
+    }
+    default:
+      CLOG_ERROR(&LOG, "\"%s.%s\", type is not string.", srna->identifier, prop->identifier);
+      DefRNA.error = true;
+      break;
+  }
+}
+
 void RNA_def_property_string_funcs_runtime(PropertyRNA *prop,
                                            StringPropertyGetFunc getfunc,
                                            StringPropertyLengthFunc lengthfunc,
@@ -3343,6 +3370,18 @@ void RNA_def_property_string_funcs_runtime(PropertyRNA *prop,
   }
 }
 
+void RNA_def_property_string_search_func_runtime(PropertyRNA *prop,
+                                                 StringPropertySearchFunc search_fn,
+                                                 const eStringPropertySearchFlag search_flag)
+{
+  StringPropertyRNA *sprop = (StringPropertyRNA *)prop;
+
+  sprop->search = search_fn;
+  if (search_fn != NULL) {
+    sprop->search_flag = search_flag | PROP_STRING_SEARCH_SUPPORTED;
+  }
+}
+
 void RNA_def_property_pointer_funcs(
     PropertyRNA *prop, const char *get, const char *set, const char *type_fn, const char *poll)
 {
diff --git a/source/blender/makesrna/intern/rna_internal_types.h b/source/blender/makesrna/intern/rna_internal_types.h
index a5b719cf753..4f88959b5ba 100644
--- a/source/blender/makesrna/intern/rna_internal_types.h
+++ b/source/blender/makesrna/intern/rna_internal_types.h
@@ -440,6 +440,15 @@ typedef struct StringPropertyRNA {
   PropStringLengthFuncEx length_ex;
   PropStringSetFuncEx set_ex;
 
+  /**
+   * Optional callback to list candidates for a string.
+   * This is only for use as suggestions in UI, other values may be assigned.
+   *
+   * \note The callback type is public, hence the difference in naming convention.
+   */
+  StringPropertySearchFunc search;
+  eStringPropertySearchFlag search_flag;
+
   int maxlength; /* includes string terminator! */
 
   const char *defaultvalue;
diff --git a/source/blender/makesrna/intern/rna_wm.c b/source/blender/makesrna/intern/rna_wm.c
index ac1b7e53a9b..c80d0e2da39 100644
--- a/source/blender/makesrna/intern/rna_wm.c
+++ b/source/blender/makesrna/intern/rna_wm.c
@@ -2599,6 +2599,9 @@ static void rna_def_keyconfig(BlenderRNA *brna)
                                 "rna_wmKeyMapItem_idname_get",
                                 "rna_wmKeyMapItem_idname_length",
                                 "rna_wmKeyMapItem_idname_set");
+  RNA_def_property_string_search_func(prop,
+                                      "WM_operatortype_idname_visit_for_search",
+                                      PROP_STRING_SEARCH_SORT | PROP_STRING_SEARCH_SUGGESTION);
   RNA_def_struct_name_property(srna, prop);
   RNA_def_property_update(prop, 0, "rna_KeyMapItem_update");