Datablock ID Properties

The absence of datablock properties "will certainly be resolved soon as the need for them is becoming obvious" said the [[http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.67/Python_Nodes|Python Nodes release notes]]. So this patch allows Python scripts to create ID Properties which reference datablocks.
This functionality is implemented for `PointerProperty` and now such properties can be created with Python.

In addition to the standard update callback, `PointerProperty` can have a `poll` callback (standard RNA) which is useful for search menus. For details see the test included in this patch.

Original author: @artfunkel

Alexander (Blend4Web Team)

Reviewers: brecht, artfunkel, mont29, campbellbarton

Reviewed By: mont29, campbellbarton

Subscribers: jta, sergey, campbellbarton, wisaac, poseidon4o, mont29, homyachetser, Evgeny_Rodygin, AlexKowel, yurikovelenov, fjuhec, sharlybg, cardboard, duarteframos, blueprintrandom, a.romanov, BYOB, disnel, aditiapratama, bliblubli, dfelinto, lukastoenne

Maniphest Tasks: T37754

Differential Revision: https://developer.blender.org/D113

5 files changed, 167 insertions, 36 deletions

diff --git a/source/blender/python/generic/idprop_py_api.c b/source/blender/python/generic/idprop_py_api.c
index 0a9931f2683..5d6a7c578a2 100644
--- a/source/blender/python/generic/idprop_py_api.c
+++ b/source/blender/python/generic/idprop_py_api.c
@@ -43,6 +43,9 @@
 
 #include "python_utildefines.h"
 
+extern bool pyrna_id_FromPyObject(PyObject *obj, ID **id);
+extern PyObject *pyrna_id_CreatePyObject(ID *id);
+extern bool pyrna_id_CheckPyObject(PyObject *obj);
 
 /*********************** ID Property Main Wrapper Stuff ***************/
 
@@ -88,6 +91,11 @@ static PyObject *idprop_py_from_idp_group(ID *id, IDProperty *prop, IDProperty *
 	return (PyObject *)group;
 }
 
+static PyObject *idprop_py_from_idp_id(IDProperty *prop)
+{
+	return pyrna_id_CreatePyObject(prop->data.pointer);
+}
+
 static PyObject *idprop_py_from_idp_array(ID *id, IDProperty *prop)
 {
 	BPy_IDProperty *array = PyObject_New(BPy_IDProperty, &BPy_IDArray_Type);
@@ -148,6 +156,7 @@ PyObject *BPy_IDGroup_WrapData(ID *id, IDProperty *prop, IDProperty *parent)
 		case IDP_GROUP:    return idprop_py_from_idp_group(id, prop, parent);
 		case IDP_ARRAY:    return idprop_py_from_idp_array(id, prop);
 		case IDP_IDPARRAY: return idprop_py_from_idp_idparray(id, prop); /* this could be better a internal type */
+		case IDP_ID:       return idprop_py_from_idp_id(prop);
 		default: Py_RETURN_NONE;
 	}
 }
@@ -586,8 +595,15 @@ static IDProperty *idp_from_PyMapping(const char *name, PyObject *ob)
 	return prop;
 }
 
+static IDProperty *idp_from_DatablockPointer(const char *name, PyObject *ob, IDPropertyTemplate *val)
+{
+	pyrna_id_FromPyObject(ob, &val->id);
+	return IDP_New(IDP_ID, val, name);
+}
+
 static IDProperty *idp_from_PyObject(PyObject *name_obj, PyObject *ob)
 {
+	IDPropertyTemplate val = {0};
 	const char *name = idp_try_read_name(name_obj);
 	if (name == NULL) {
 		return NULL;
@@ -608,6 +624,9 @@ static IDProperty *idp_from_PyObject(PyObject *name_obj, PyObject *ob)
 	else if (PySequence_Check(ob)) {
 		return idp_from_PySequence(name, ob);
 	}
+	else if (ob == Py_None || pyrna_id_CheckPyObject(ob)) {
+		return idp_from_DatablockPointer(name, ob, &val);
+	}
 	else if (PyMapping_Check(ob)) {
 		return idp_from_PyMapping(name, ob);
 	}
@@ -732,6 +751,8 @@ static PyObject *BPy_IDGroup_MapDataToPy(IDProperty *prop)
 			return idprop_py_from_idp_float(prop);
 		case IDP_DOUBLE:
 			return idprop_py_from_idp_double(prop);
+		case IDP_ID:
+			return idprop_py_from_idp_id(prop);
 		case IDP_ARRAY:
 		{
 			PyObject *seq = PyList_New(prop->len);
diff --git a/source/blender/python/intern/bpy_props.c b/source/blender/python/intern/bpy_props.c
index f7348ac2250..2656e612b18 100644
--- a/source/blender/python/intern/bpy_props.c
+++ b/source/blender/python/intern/bpy_props.c
@@ -50,11 +50,13 @@
 #include "../generic/py_capi_utils.h"
 
 /* initial definition of callback slots we'll probably have more than 1 */
-#define BPY_DATA_CB_SLOT_SIZE 3
-
-#define BPY_DATA_CB_SLOT_UPDATE 0
-#define BPY_DATA_CB_SLOT_GET 1
-#define BPY_DATA_CB_SLOT_SET 2
+enum {
+	BPY_DATA_CB_SLOT_UPDATE     = 0,
+	BPY_DATA_CB_SLOT_GET        = 1,
+	BPY_DATA_CB_SLOT_SET        = 2,
+	BPY_DATA_CB_SLOT_POLL       = 3,
+	BPY_DATA_CB_SLOT_SIZE       = 4,
+};
 
 extern BPy_StructRNA *bpy_context_module;
 
@@ -71,6 +73,9 @@ static EnumPropertyItem property_flag_items[] = {
 "   :arg options: Enumerator in ['HIDDEN', 'SKIP_SAVE', 'ANIMATABLE', 'LIBRARY_EDITABLE', 'PROPORTIONAL'," \
                                 "'TEXTEDIT_UPDATE'].\n" \
 "   :type options: set\n" \
+"   :arg poll: function to be called to determine whether an item is valid for this property.\n" \
+"              The function must take 2 values (self,object) and return Bool.\n" \
+"   :type poll: function\n" \
 
 static EnumPropertyItem property_flag_enum_items[] = {
 	{PROP_HIDDEN, "HIDDEN", 0, "Hidden", ""},
@@ -389,6 +394,51 @@ static void bpy_prop_boolean_set_cb(struct PointerRNA *ptr, struct PropertyRNA *
 	}
 }
 
+static int bpy_prop_poll_cb(struct PointerRNA *self, PointerRNA candidate, struct PropertyRNA *prop)
+{
+	PyObject *py_self;
+	PyObject *py_candidate;
+	PyObject *py_func;
+	PyObject **py_data = RNA_property_py_data_get(prop);
+	PyObject *args;
+	PyObject *ret;
+	bool result;
+	const int is_write_ok = pyrna_write_check();
+	PyGILState_STATE gilstate = PyGILState_Ensure();
+
+	BLI_assert(self != NULL);
+
+	py_self = pyrna_struct_as_instance(self);
+	py_candidate = pyrna_struct_as_instance(&candidate);
+	py_func = py_data[BPY_DATA_CB_SLOT_POLL];
+
+	if (!is_write_ok)
+		pyrna_write_set(true);
+
+	args = PyTuple_New(2);
+	PyTuple_SET_ITEM(args, 0, py_self);
+	PyTuple_SET_ITEM(args, 1, py_candidate);
+
+	ret = PyObject_CallObject(py_func, args);
+
+	Py_DECREF(args);
+
+	if (ret == NULL) {
+		printf_func_error(py_func);
+		result = false;
+	}
+	else {
+		result = PyObject_IsTrue(ret);
+		Py_DECREF(ret);
+	}
+
+	PyGILState_Release(gilstate);
+	if (!is_write_ok)
+		pyrna_write_set(false);
+
+	return result;
+}
+
 static void bpy_prop_boolean_array_get_cb(struct PointerRNA *ptr, struct PropertyRNA *prop, int *values)
 {
 	PyObject **py_data = RNA_property_py_data_get(prop);
@@ -1598,6 +1648,16 @@ static void bpy_prop_callback_assign_update(struct PropertyRNA *prop, PyObject *
 	}
 }
 
+static void bpy_prop_callback_assign_pointer(struct PropertyRNA *prop, PyObject *poll_cb)
+{
+	if (poll_cb && poll_cb != Py_None) {
+		PyObject **py_data = bpy_prop_py_data_get(prop);
+
+		RNA_def_property_poll_runtime(prop, (void *) bpy_prop_poll_cb);
+		py_data[BPY_DATA_CB_SLOT_POLL] = poll_cb;
+	}
+}
+
 static void bpy_prop_callback_assign_boolean(struct PropertyRNA *prop, PyObject *get_cb, PyObject *set_cb)
 {
 	BooleanPropertyGetFunc rna_get_cb = NULL;
@@ -1904,7 +1964,7 @@ static void bpy_prop_callback_assign_enum(struct PropertyRNA *prop, PyObject *ge
 "   :type set: function\n" \
 
 #define BPY_PROPDEF_TYPE_DOC \
-"   :arg type: A subclass of :class:`bpy.types.PropertyGroup`.\n" \
+"   :arg type: A subclass of :class:`bpy.types.PropertyGroup` or :class:`bpy.types.ID`.\n" \
 "   :type type: class\n" \
 
 #if 0
@@ -2772,7 +2832,7 @@ static PyObject *BPy_EnumProperty(PyObject *self, PyObject *args, PyObject *kw)
 	Py_RETURN_NONE;
 }
 
-static StructRNA *pointer_type_from_py(PyObject *value, const char *error_prefix)
+StructRNA *pointer_type_from_py(PyObject *value, const char *error_prefix)
 {
 	StructRNA *srna;
 
@@ -2782,25 +2842,18 @@ static StructRNA *pointer_type_from_py(PyObject *value, const char *error_prefix
 			PyObject *msg = PyC_ExceptionBuffer();
 			const char *msg_char = _PyUnicode_AsString(msg);
 			PyErr_Format(PyExc_TypeError,
-			             "%.200s expected an RNA type derived from PropertyGroup, failed with: %s",
+			             "%.200s expected an RNA type, failed with: %s",
 			             error_prefix, msg_char);
 			Py_DECREF(msg);
 		}
 		else {
 			PyErr_Format(PyExc_TypeError,
-			             "%.200s expected an RNA type derived from PropertyGroup, failed with type '%s'",
+			             "%.200s expected an RNA type, failed with type '%s'",
 			             error_prefix, Py_TYPE(value)->tp_name);
 		}
 		return NULL;
 	}
 
-	if (!RNA_struct_is_a(srna, &RNA_PropertyGroup)) {
-		PyErr_Format(PyExc_TypeError,
-		             "%.200s expected an RNA type derived from PropertyGroup",
-		             error_prefix);
-		return NULL;
-	}
-
 	return srna;
 }
 
@@ -2809,7 +2862,8 @@ PyDoc_STRVAR(BPy_PointerProperty_doc,
                               "name=\"\", "
                               "description=\"\", "
                               "options={'ANIMATABLE'}, "
-                              "update=None)\n"
+                              "update=None,\n"
+                              "poll=None)\n"
 "\n"
 "   Returns a new pointer property definition.\n"
 "\n"
@@ -2819,14 +2873,14 @@ BPY_PROPDEF_DESC_DOC
 BPY_PROPDEF_OPTIONS_DOC
 BPY_PROPDEF_UPDATE_DOC
 );
-static PyObject *BPy_PointerProperty(PyObject *self, PyObject *args, PyObject *kw)
+PyObject *BPy_PointerProperty(PyObject *self, PyObject *args, PyObject *kw)
 {
 	StructRNA *srna;
 
 	BPY_PROPDEF_HEAD(PointerProperty);
 
 	if (srna) {
-		static const char *kwlist[] = {"attr", "type", "name", "description", "options", "update", NULL};
+		static const char *kwlist[] = {"attr", "type", "name", "description", "options", "poll", "update", NULL};
 		const char *id = NULL, *name = NULL, *description = "";
 		int id_len;
 		PropertyRNA *prop;
@@ -2834,33 +2888,47 @@ static PyObject *BPy_PointerProperty(PyObject *self, PyObject *args, PyObject *k
 		PyObject *type = Py_None;
 		PyObject *pyopts = NULL;
 		int opts = 0;
-		PyObject *update_cb = NULL;
+		PyObject *update_cb = NULL, *poll_cb = NULL;
 
 		if (!PyArg_ParseTupleAndKeywords(args, kw,
-		                                 "s#O|ssO!O:PointerProperty",
+		                                 "s#O|ssO!OOO:PointerProperty",
 		                                 (char **)kwlist, &id, &id_len,
 		                                 &type, &name, &description,
 		                                 &PySet_Type, &pyopts,
-		                                 &update_cb))
+		                                 &poll_cb, &update_cb))
 		{
 			return NULL;
 		}
 
 		BPY_PROPDEF_CHECK(PointerProperty, property_flag_items);
 
-		ptype = pointer_type_from_py(type, "PointerProperty(...):");
+		ptype = pointer_type_from_py(type, "PointerProperty(...)");
 		if (!ptype)
 			return NULL;
-
+		if (!RNA_struct_is_a(ptype, &RNA_PropertyGroup) && !RNA_struct_is_ID(ptype)) {
+			PyErr_Format(PyExc_TypeError,
+			             "PointerProperty(...) expected an RNA type derived from %.200s or %.200s",
+			             RNA_struct_ui_name(&RNA_ID), RNA_struct_ui_name(&RNA_PropertyGroup));
+			return NULL;
+		}
 		if (bpy_prop_callback_check(update_cb, "update", 2) == -1) {
 			return NULL;
 		}
-
+		if (bpy_prop_callback_check(poll_cb, "poll", 2) == -1) {
+			return NULL;
+		}
 		prop = RNA_def_pointer_runtime(srna, id, ptype, name ? name : id, description);
 		if (pyopts) {
 			bpy_prop_assign_flag(prop, opts);
 		}
+
+		if (RNA_struct_idprops_contains_datablock(ptype)) {
+			if (RNA_struct_is_a(srna, &RNA_PropertyGroup)) {
+				RNA_def_struct_flag(srna, STRUCT_CONTAINS_DATABLOCK_IDPROPERTIES);
+			}
+		}
 		bpy_prop_callback_assign_update(prop, update_cb);
+		bpy_prop_callback_assign_pointer(prop, poll_cb);
 		RNA_def_property_duplicate_pointers(srna, prop);
 	}
 	Py_RETURN_NONE;
@@ -2879,7 +2947,7 @@ BPY_PROPDEF_NAME_DOC
 BPY_PROPDEF_DESC_DOC
 BPY_PROPDEF_OPTIONS_DOC
 );
-static PyObject *BPy_CollectionProperty(PyObject *self, PyObject *args, PyObject *kw)
+PyObject *BPy_CollectionProperty(PyObject *self, PyObject *args, PyObject *kw)
 {
 	StructRNA *srna;
 
@@ -2910,10 +2978,23 @@ static PyObject *BPy_CollectionProperty(PyObject *self, PyObject *args, PyObject
 		if (!ptype)
 			return NULL;
 
+		if (!RNA_struct_is_a(ptype, &RNA_PropertyGroup)) {
+			PyErr_Format(PyExc_TypeError,
+				"CollectionProperty(...) expected an RNA type derived from %.200s",
+				RNA_struct_ui_name(&RNA_ID), RNA_struct_ui_name(&RNA_PropertyGroup));
+			return NULL;
+		}
+
 		prop = RNA_def_collection_runtime(srna, id, ptype, name ? name : id, description);
 		if (pyopts) {
 			bpy_prop_assign_flag(prop, opts);
 		}
+
+		if (RNA_struct_idprops_contains_datablock(ptype)) {
+			if (RNA_struct_is_a(srna, &RNA_PropertyGroup)) {
+				RNA_def_struct_flag(srna, STRUCT_CONTAINS_DATABLOCK_IDPROPERTIES);
+			}
+		}
 		RNA_def_property_duplicate_pointers(srna, prop);
 	}
 	Py_RETURN_NONE;
diff --git a/source/blender/python/intern/bpy_props.h b/source/blender/python/intern/bpy_props.h
index c9934ca0cf3..614c1b4b708 100644
--- a/source/blender/python/intern/bpy_props.h
+++ b/source/blender/python/intern/bpy_props.h
@@ -30,6 +30,10 @@
 
 PyObject *BPY_rna_props(void);
 
+PyObject *BPy_PointerProperty(PyObject *self, PyObject *args, PyObject *kw);
+PyObject *BPy_CollectionProperty(PyObject *self, PyObject *args, PyObject *kw);
+StructRNA *pointer_type_from_py(PyObject *value, const char *error_prefix);
+
 #define PYRNA_STACK_ARRAY 32
 
 #endif
diff --git a/source/blender/python/intern/bpy_rna.c b/source/blender/python/intern/bpy_rna.c
index 2fd46ab94f0..00627030db3 100644
--- a/source/blender/python/intern/bpy_rna.c
+++ b/source/blender/python/intern/bpy_rna.c
@@ -1934,16 +1934,10 @@ static int pyrna_py_to_prop(
 					}
 					else {
 						/* data == NULL, assign to RNA */
-						if (value == Py_None) {
-							PointerRNA valueptr = {{NULL}};
-							RNA_property_pointer_set(ptr, prop, valueptr);
-						}
-						else if (RNA_struct_is_a(param->ptr.type, ptr_type)) {
-							RNA_property_pointer_set(ptr, prop, param->ptr);
-						}
-						else {
+						if (value == Py_None || RNA_struct_is_a(param->ptr.type, ptr_type))
+							RNA_property_pointer_set(ptr, prop, value == Py_None ? PointerRNA_NULL : param->ptr);
+						else
 							raise_error = true;
-						}
 					}
 
 					if (raise_error) {
@@ -3277,6 +3271,16 @@ static int pyrna_struct_ass_subscript(BPy_StructRNA *self, PyObject *key, PyObje
 		return -1;
 	}
 
+	BPy_StructRNA *val = (BPy_StructRNA *)value;
+	if (val && self->ptr.type && val->ptr.type) {
+		if (!RNA_struct_idprops_datablock_allowed(self->ptr.type) &&
+		    RNA_struct_idprops_contains_datablock(val->ptr.type))
+		{
+			PyErr_SetString(PyExc_TypeError, "bpy_struct[key] = val: datablock id properties not supported for this type");
+			return -1;
+		}
+	}
+
 	return BPy_Wrap_SetMapItem(group, key, value);
 }
 
@@ -6745,7 +6749,7 @@ PyObject *pyrna_id_CreatePyObject(ID *id)
 
 bool pyrna_id_FromPyObject(PyObject *obj, ID **id)
 {
-	if (BPy_StructRNA_Check(obj) && (RNA_struct_is_ID(((BPy_StructRNA *)obj)->ptr.type))) {
+	if (pyrna_id_CheckPyObject(obj)) {
 		*id = ((BPy_StructRNA *)obj)->ptr.id.data;
 		return true;
 	}
@@ -6755,6 +6759,11 @@ bool pyrna_id_FromPyObject(PyObject *obj, ID **id)
 	}
 }
 
+bool pyrna_id_CheckPyObject(PyObject *obj)
+{
+	return BPy_StructRNA_Check(obj) && (RNA_struct_is_ID(((BPy_StructRNA *) obj)->ptr.type));
+}
+
 void BPY_rna_init(void)
 {
 #ifdef USE_MATHUTILS  /* register mathutils callbacks, ok to run more than once. */
@@ -7089,6 +7098,21 @@ static int deferred_register_prop(StructRNA *srna, PyObject *key, PyObject *item
 			args_fake = PyTuple_New(1);
 			PyTuple_SET_ITEM(args_fake, 0, py_srna_cobject);
 
+			PyObject *type = PyDict_GetItemString(py_kw, "type");
+			StructRNA *type_srna = srna_from_self(type, "");
+			if (type_srna) {
+				if (!RNA_struct_idprops_datablock_allowed(srna) &&
+				    (*(PyCFunctionWithKeywords)PyCFunction_GET_FUNCTION(py_func) == BPy_PointerProperty ||
+				     *(PyCFunctionWithKeywords)PyCFunction_GET_FUNCTION(py_func) == BPy_CollectionProperty) &&
+				    RNA_struct_idprops_contains_datablock(type_srna))
+				{
+					PyErr_Format(PyExc_ValueError,
+								 "bpy_struct \"%.200s\" doesn't support datablock properties \n",
+								 RNA_struct_identifier(srna));
+					return -1;
+				}
+			}
+
 			py_ret = PyObject_Call(py_func, args_fake, py_kw);
 
 			if (py_ret) {
diff --git a/source/blender/python/intern/bpy_rna.h b/source/blender/python/intern/bpy_rna.h
index e38d4f095d6..605f79b1ad8 100644
--- a/source/blender/python/intern/bpy_rna.h
+++ b/source/blender/python/intern/bpy_rna.h
@@ -179,6 +179,7 @@ PyObject *pyrna_prop_CreatePyObject(PointerRNA *ptr, PropertyRNA *prop);
 /* extern'd by other modules which don't deal closely with RNA */
 PyObject *pyrna_id_CreatePyObject(struct ID *id);
 bool      pyrna_id_FromPyObject(PyObject *obj, struct ID **id);
+bool      pyrna_id_CheckPyObject(PyObject *obj);
 
 /* operators also need this to set args */
 int pyrna_pydict_to_props(PointerRNA *ptr, PyObject *kw, const bool all_args, const char *error_prefix);