Refactor IDProperty UI data storage

The storage of IDProperty UI data (min, max, default value, etc) is
quite complicated. For every property, retrieving a single one of these
values involves three string lookups. First for the "_RNA_UI" group
property, then another for a group with the property's name, then for
the data value name. Not only is this inefficient, it's hard to reason
about, unintuitive, and not at all self-explanatory.

This commit replaces that system with a UI data struct directly in the
IDProperty. If it's not used, the only cost is of a NULL pointer. Beyond
storing the description, name, and RNA subtype, derived structs are used
to store type specific UI data like min and max.

Note that this means that addons using (abusing) the `_RNA_UI` custom
property will have to be changed. A few places in the addons repository
will be changed after this commit with D9919.

**Before**
Before, first the _RNA_UI subgroup is retrieved the _RNA_UI group,
then the subgroup for the original property, then specific UI data
is accessed like any other IDProperty.
```
prop = rna_idprop_ui_prop_get(idproperties_owner, "prop_name", create=True)
prop["min"] = 1.0
```

**After**
After, the `id_properties_ui` function for RNA structs returns a python
object specifically for managing an IDProperty's UI data.
```
ui_data = idproperties_owner.id_properties_ui("prop_name")
ui_data.update(min=1.0)
```
In addition to `update`, there are now other functions:
 - `as_dict`: Returns a dictionary of the property's UI data.
 - `clear`: Removes the property's UI data.
 - `update_from`: Copy UI data between properties,
   even if they have different owners.

Differential Revision: https://developer.blender.org/D9697

1 files changed, 27 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_idprop.h b/source/blender/blenkernel/BKE_idprop.h
index a5cb6489194..c28ac63388b 100644
--- a/source/blender/blenkernel/BKE_idprop.h
+++ b/source/blender/blenkernel/BKE_idprop.h
@@ -32,6 +32,7 @@ struct BlendLibReader;
 struct BlendWriter;
 struct ID;
 struct IDProperty;
+struct IDPropertyUIData;
 
 typedef union IDPropertyTemplate {
   int i;
@@ -183,6 +184,10 @@ void IDP_Reset(struct IDProperty *prop, const struct IDProperty *reference);
 #  define IDP_Id(prop) ((ID *)(prop)->data.pointer)
 #endif
 
+int IDP_coerce_to_int_or_zero(const struct IDProperty *prop);
+float IDP_coerce_to_float_or_zero(const struct IDProperty *prop);
+double IDP_coerce_to_double_or_zero(const struct IDProperty *prop);
+
 /**
  * Call a callback for each idproperty in the hierarchy under given root one (included).
  *
@@ -209,6 +214,28 @@ void IDP_BlendReadData_impl(struct BlendDataReader *reader,
 void IDP_BlendReadLib(struct BlendLibReader *reader, struct IDProperty *prop);
 void IDP_BlendReadExpand(struct BlendExpander *expander, struct IDProperty *prop);
 
+typedef enum eIDPropertyUIDataType {
+  /** Other properties types that don't support RNA UI data. */
+  IDP_UI_DATA_TYPE_UNSUPPORTED = -1,
+  /** IDP_INT or IDP_ARRAY with subtype IDP_INT. */
+  IDP_UI_DATA_TYPE_INT = 0,
+  /** IDP_FLOAT and IDP_DOUBLE or IDP_ARRAY properties with a float or double subtypes. */
+  IDP_UI_DATA_TYPE_FLOAT = 1,
+  /** IDP_STRING properties. */
+  IDP_UI_DATA_TYPE_STRING = 2,
+  /** IDP_ID. */
+  IDP_UI_DATA_TYPE_ID = 3,
+} eIDPropertyUIDataType;
+
+bool IDP_ui_data_supported(const struct IDProperty *prop);
+eIDPropertyUIDataType IDP_ui_data_type(const struct IDProperty *prop);
+void IDP_ui_data_free(struct IDProperty *prop);
+void IDP_ui_data_free_unique_contents(struct IDPropertyUIData *ui_data,
+                                      eIDPropertyUIDataType type,
+                                      const struct IDPropertyUIData *other);
+struct IDPropertyUIData *IDP_ui_data_ensure(struct IDProperty *prop);
+struct IDPropertyUIData *IDP_ui_data_copy(const struct IDProperty *prop);
+
 #ifdef __cplusplus
 }
 #endif