Asset System: Data-block asset metadata storage, reading and API

Asset metadata is what turns a regular data-block into an asset. It is a small
data-structure, but a key part of the technical design of the asset system.

The design foresees that asset data-blocks store an `ID.asset_data` pointer of
type `AssetMetaData`. This data **must not** have dependencies on other
data-blocks or data-block data, it must be an independent unit. That way we can
read asset-metadata from .blends without reading anything else from the file.
The Asset Browser will use this metadata (together with the data-block name,
preview and file path) to represent assets in the file list.

Includes:
* New `ID.asset_data` for asset metadata.
* Asset tags, description and custom properties.
* BKE code to manage asset meta-data and asset tags.
* Code to read asset data from files, without reading IDs.
* RNA for asset metadata (including tags)

Part of the first Asset Browser milestone. Check the #asset_browser_milestone_1
project milestone on developer.blender.org.

Differential Revision: https://developer.blender.org/D9716

Reviewed by: Bastien Montagne, Brecht Van Lommel

6 files changed, 238 insertions, 0 deletions

diff --git a/source/blender/makesrna/RNA_access.h b/source/blender/makesrna/RNA_access.h
index 4aeb9b9e5f7..da15489370a 100644
--- a/source/blender/makesrna/RNA_access.h
+++ b/source/blender/makesrna/RNA_access.h
@@ -70,6 +70,8 @@ extern StructRNA RNA_ArrayGpencilModifier;
 extern StructRNA RNA_ArrayModifier;
 extern StructRNA RNA_Attribute;
 extern StructRNA RNA_AttributeGroup;
+extern StructRNA RNA_AssetMetaData;
+extern StructRNA RNA_AssetTag;
 extern StructRNA RNA_BackgroundImage;
 extern StructRNA RNA_BevelModifier;
 extern StructRNA RNA_BezierSplinePoint;
diff --git a/source/blender/makesrna/intern/CMakeLists.txt b/source/blender/makesrna/intern/CMakeLists.txt
index 3ebbb98934e..2ce1acb0074 100644
--- a/source/blender/makesrna/intern/CMakeLists.txt
+++ b/source/blender/makesrna/intern/CMakeLists.txt
@@ -31,6 +31,7 @@ set(DEFSRC
   rna_animviz.c
   rna_armature.c
   rna_attribute.c
+  rna_asset.c
   rna_boid.c
   rna_brush.c
   rna_cachefile.c
diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index 8b861d20e4e..c2c95c59002 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -4270,6 +4270,7 @@ static RNAProcessItem PROCESS_ITEMS[] = {
     {"rna_animviz.c", NULL, RNA_def_animviz},
     {"rna_armature.c", "rna_armature_api.c", RNA_def_armature},
     {"rna_attribute.c", NULL, RNA_def_attribute},
+    {"rna_asset.c", NULL, RNA_def_asset},
     {"rna_boid.c", NULL, RNA_def_boid},
     {"rna_brush.c", NULL, RNA_def_brush},
     {"rna_cachefile.c", NULL, RNA_def_cachefile},
diff --git a/source/blender/makesrna/intern/rna_ID.c b/source/blender/makesrna/intern/rna_ID.c
index f63cf0271b8..7c67bfc360b 100644
--- a/source/blender/makesrna/intern/rna_ID.c
+++ b/source/blender/makesrna/intern/rna_ID.c
@@ -1528,6 +1528,11 @@ static void rna_def_ID(BlenderRNA *brna)
   RNA_def_property_override_flag(prop, PROPOVERRIDE_NO_COMPARISON);
   RNA_def_property_ui_text(prop, "Library", "Library file the data-block is linked from");
 
+  prop = RNA_def_property(srna, "asset_data", PROP_POINTER, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_override_flag(prop, PROPOVERRIDE_NO_COMPARISON);
+  RNA_def_property_ui_text(prop, "Asset Data", "Additional data for an asset data-block");
+
   prop = RNA_def_pointer(
       srna, "override_library", "IDOverrideLibrary", "Library Override", "Library override data");
   RNA_def_property_clear_flag(prop, PROP_EDITABLE);
diff --git a/source/blender/makesrna/intern/rna_asset.c b/source/blender/makesrna/intern/rna_asset.c
new file mode 100644
index 00000000000..1af53e95cc9
--- /dev/null
+++ b/source/blender/makesrna/intern/rna_asset.c
@@ -0,0 +1,228 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup RNA
+ */
+
+#include <stdlib.h>
+
+#include "RNA_define.h"
+#include "RNA_enum_types.h"
+
+#include "DNA_asset_types.h"
+#include "DNA_defs.h"
+
+#include "rna_internal.h"
+
+#ifdef RNA_RUNTIME
+
+#  include "BKE_asset.h"
+#  include "BKE_idprop.h"
+
+#  include "BLI_listbase.h"
+
+#  include "RNA_access.h"
+
+static AssetTag *rna_AssetMetaData_tag_new(AssetMetaData *asset_data,
+                                           ReportList *reports,
+                                           const char *name,
+                                           bool skip_if_exists)
+{
+  AssetTag *tag = NULL;
+
+  if (skip_if_exists) {
+    struct AssetTagEnsureResult result = BKE_asset_metadata_tag_ensure(asset_data, name);
+
+    if (!result.is_new) {
+      BKE_reportf(
+          reports, RPT_WARNING, "Tag '%s' already present for given asset", result.tag->name);
+      /* Report, but still return valid item. */
+    }
+    tag = result.tag;
+  }
+  else {
+    tag = BKE_asset_metadata_tag_add(asset_data, name);
+  }
+
+  return tag;
+}
+
+static void rna_AssetMetaData_tag_remove(AssetMetaData *asset_data,
+                                         ReportList *reports,
+                                         PointerRNA *tag_ptr)
+{
+  AssetTag *tag = tag_ptr->data;
+  if (BLI_findindex(&asset_data->tags, tag) == -1) {
+    BKE_reportf(reports, RPT_ERROR, "Tag '%s' not found in given asset", tag->name);
+    return;
+  }
+
+  BKE_asset_metadata_tag_remove(asset_data, tag);
+  RNA_POINTER_INVALIDATE(tag_ptr);
+}
+
+static IDProperty *rna_AssetMetaData_idprops(PointerRNA *ptr, bool create)
+{
+  AssetMetaData *asset_data = ptr->data;
+
+  if (create && !asset_data->properties) {
+    IDPropertyTemplate val = {0};
+    asset_data->properties = IDP_New(IDP_GROUP, &val, "RNA_AssetMetaData group");
+  }
+
+  return asset_data->properties;
+}
+
+static void rna_AssetMetaData_description_get(PointerRNA *ptr, char *value)
+{
+  AssetMetaData *asset_data = ptr->data;
+
+  if (asset_data->description) {
+    strcpy(value, asset_data->description);
+  }
+  else {
+    value[0] = '\0';
+  }
+}
+
+static int rna_AssetMetaData_description_length(PointerRNA *ptr)
+{
+  AssetMetaData *asset_data = ptr->data;
+  return asset_data->description ? strlen(asset_data->description) : 0;
+}
+
+static void rna_AssetMetaData_description_set(PointerRNA *ptr, const char *value)
+{
+  AssetMetaData *asset_data = ptr->data;
+
+  if (asset_data->description) {
+    MEM_freeN(asset_data->description);
+  }
+
+  if (value[0]) {
+    asset_data->description = BLI_strdup(value);
+  }
+  else {
+    asset_data->description = NULL;
+  }
+}
+
+static void rna_AssetMetaData_active_tag_range(
+    PointerRNA *ptr, int *min, int *max, int *softmin, int *softmax)
+{
+  const AssetMetaData *asset_data = ptr->data;
+  *min = *softmin = 0;
+  *max = *softmax = MAX2(asset_data->tot_tags - 1, 0);
+}
+
+#else
+
+static void rna_def_asset_tag(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "AssetTag", NULL);
+  RNA_def_struct_ui_text(srna, "Asset Tag", "User defined tag (name token)");
+
+  prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_maxlength(prop, MAX_NAME);
+  RNA_def_property_ui_text(prop, "Name", "The identifier that makes up this tag");
+  RNA_def_struct_name_property(srna, prop);
+}
+
+static void rna_def_asset_tags_api(BlenderRNA *brna, PropertyRNA *cprop)
+{
+  StructRNA *srna;
+
+  FunctionRNA *func;
+  PropertyRNA *parm;
+
+  RNA_def_property_srna(cprop, "AssetTags");
+  srna = RNA_def_struct(brna, "AssetTags", NULL);
+  RNA_def_struct_sdna(srna, "AssetMetaData");
+  RNA_def_struct_ui_text(srna, "Asset Tags", "Collection of custom asset tags");
+
+  /* Tag collection */
+  func = RNA_def_function(srna, "new", "rna_AssetMetaData_tag_new");
+  RNA_def_function_ui_description(func, "Add a new tag to this asset");
+  RNA_def_function_flag(func, FUNC_USE_REPORTS);
+  parm = RNA_def_string(func, "name", NULL, MAX_NAME, "Name", "");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_boolean(func,
+                         "skip_if_exists",
+                         false,
+                         "Skip if Exists",
+                         "Do not add a new tag if one of the same type already exists");
+  /* return type */
+  parm = RNA_def_pointer(func, "tag", "AssetTag", "", "New tag");
+  RNA_def_function_return(func, parm);
+
+  func = RNA_def_function(srna, "remove", "rna_AssetMetaData_tag_remove");
+  RNA_def_function_ui_description(func, "Remove an existing tag from this asset");
+  RNA_def_function_flag(func, FUNC_USE_REPORTS);
+  /* tag to remove */
+  parm = RNA_def_pointer(func, "tag", "AssetTag", "", "Removed tag");
+  RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED | PARM_RNAPTR);
+  RNA_def_parameter_clear_flags(parm, PROP_THICK_WRAP, 0);
+}
+
+static void rna_def_asset_data(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "AssetMetaData", NULL);
+  RNA_def_struct_ui_text(srna, "Asset Data", "Additional data stored for an asset data-block");
+  //  RNA_def_struct_ui_icon(srna, ICON_ASSET); /* TODO: Icon doesn't exist!. */
+  /* The struct has custom properties, but no pointer properties to other IDs! */
+  RNA_def_struct_idprops_func(srna, "rna_AssetMetaData_idprops");
+  RNA_def_struct_flag(srna, STRUCT_NO_DATABLOCK_IDPROPERTIES); /* Mandatory! */
+
+  prop = RNA_def_property(srna, "description", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_funcs(prop,
+                                "rna_AssetMetaData_description_get",
+                                "rna_AssetMetaData_description_length",
+                                "rna_AssetMetaData_description_set");
+  RNA_def_property_ui_text(
+      prop, "Description", "A description of the asset to be displayed for the user");
+
+  prop = RNA_def_property(srna, "tags", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "AssetTag");
+  RNA_def_property_flag(prop, PROP_EDITABLE);
+  RNA_def_property_ui_text(prop,
+                           "Tags",
+                           "Custom tags (name tokens) for the asset, used for filtering and "
+                           "general asset management");
+  rna_def_asset_tags_api(brna, prop);
+
+  prop = RNA_def_property(srna, "active_tag", PROP_INT, PROP_NONE);
+  RNA_def_property_int_funcs(prop, NULL, NULL, "rna_AssetMetaData_active_tag_range");
+  RNA_def_property_ui_text(prop, "Active Tag", "Index of the tag set for editing");
+}
+
+void RNA_def_asset(BlenderRNA *brna)
+{
+  RNA_define_animate_sdna(false);
+
+  rna_def_asset_tag(brna);
+  rna_def_asset_data(brna);
+
+  RNA_define_animate_sdna(true);
+}
+
+#endif
diff --git a/source/blender/makesrna/intern/rna_internal.h b/source/blender/makesrna/intern/rna_internal.h
index d4fdac390b2..76c3e17e128 100644
--- a/source/blender/makesrna/intern/rna_internal.h
+++ b/source/blender/makesrna/intern/rna_internal.h
@@ -152,6 +152,7 @@ void RNA_def_animation(struct BlenderRNA *brna);
 void RNA_def_animviz(struct BlenderRNA *brna);
 void RNA_def_armature(struct BlenderRNA *brna);
 void RNA_def_attribute(struct BlenderRNA *brna);
+void RNA_def_asset(struct BlenderRNA *brna);
 void RNA_def_boid(struct BlenderRNA *brna);
 void RNA_def_brush(struct BlenderRNA *brna);
 void RNA_def_cachefile(struct BlenderRNA *brna);