Python i18n API. Many thanks to Campbell and Brecht for the reviews and suggestions!

This commit adds:
* A new bpy.app.translations module giving some info about locales/translation stuff (current active locale, all locales currently known by blender, all translation contexts currently defined, etc.).

* The ability for addons to feature translations, using the (un)register functions of above module.

* Also cleans up "translate py string when storing into RNA prop" by removing "PROP_TRANSLATE" string's subtype, and adding a PROP_STRING_PY_TRANSLATE flag instead (this way it is no more exposed to python...).

Addon translations work with py dictionaries: each addon features a dict {lang: {(context, message): translation, ...}, ...}, which is registered when the addon is enabled (and unregistered when disabled). 

Then, when a key (context, message) is not found in regular mo catalog, a cache dict for current locale is built from all registered addon translations, and key is searched in it.

Note: currently addons writers have to do all the work by hand, will add something (probably extend "edit translation" addon) to automate messages extraction from addons soon(ish)! To get a look to expected behavior from addons, have a look at render_copy_settings/__init__.py and render_copy_settings/translations.py (rather stupid example currently, but...). Once we have a complete process, I'll also update relevant wiki pages.

8 files changed, 21 insertions, 25 deletions

diff --git a/source/blender/makesrna/RNA_define.h b/source/blender/makesrna/RNA_define.h
index 463e0e04679..cd6d74c3488 100644
--- a/source/blender/makesrna/RNA_define.h
+++ b/source/blender/makesrna/RNA_define.h
@@ -87,7 +87,7 @@ PropertyRNA *RNA_def_string(StructOrFunctionRNA *cont, const char *identifier, c
 PropertyRNA *RNA_def_string_file_path(StructOrFunctionRNA *cont, const char *identifier, const char *default_value, int maxlen, const char *ui_name, const char *ui_description);
 PropertyRNA *RNA_def_string_dir_path(StructOrFunctionRNA *cont, const char *identifier, const char *default_value, int maxlen, const char *ui_name, const char *ui_description);
 PropertyRNA *RNA_def_string_file_name(StructOrFunctionRNA *cont, const char *identifier, const char *default_value, int maxlen, const char *ui_name, const char *ui_description);
-PropertyRNA *RNA_def_string_translate(StructOrFunctionRNA *cont, const char *identifier, const char *default_value, int maxlen, const char *ui_name, const char *ui_description);
+PropertyRNA *RNA_def_string_py_translate(StructOrFunctionRNA *cont, const char *identifier, const char *default_value, int maxlen, const char *ui_name, const char *ui_description);
 
 PropertyRNA *RNA_def_enum(StructOrFunctionRNA *cont, const char *identifier, const EnumPropertyItem *items, int default_value, const char *ui_name, const char *ui_description);
 PropertyRNA *RNA_def_enum_flag(StructOrFunctionRNA *cont, const char *identifier, const EnumPropertyItem *items, int default_value, const char *ui_name, const char *ui_description);
diff --git a/source/blender/makesrna/RNA_types.h b/source/blender/makesrna/RNA_types.h
index c76f9824c73..5f34fad09c6 100644
--- a/source/blender/makesrna/RNA_types.h
+++ b/source/blender/makesrna/RNA_types.h
@@ -110,10 +110,9 @@ typedef enum PropertySubType {
 	PROP_FILEPATH = 1,
 	PROP_DIRPATH = 2,
 	PROP_FILENAME = 3,
-	PROP_BYTESTRING = 4, /* a string which should be represented as bytes
-	                      * in python, still NULL terminated though. */
-	PROP_TRANSLATE = 5, /* a string which should be translated */
-	PROP_PASSWORD = 6,	/* a string which should not be displayed in UI */
+	PROP_BYTESTRING = 4, /* a string which should be represented as bytes in python, still NULL terminated though. */
+	/* 5 was used by "PROP_TRANSLATE" sub-type, which is now a flag. */
+	PROP_PASSWORD = 6, /* a string which should not be displayed in UI */
 
 	/* numbers */
 	PROP_UNSIGNED = 13,
@@ -144,6 +143,7 @@ typedef enum PropertySubType {
 } PropertySubType;
 
 /* Make sure enums are updated with thses */
+/* HIGHEST FLAG IN USE: 1 << 29 */
 typedef enum PropertyFlag {
 	/* editable means the property is editable in the user
 	 * interface, properties are editable by default except
@@ -200,6 +200,11 @@ typedef enum PropertyFlag {
 	 */
 	PROP_ENUM_FLAG = (1 << 21),
 
+	/* A string which should be translated when converting from py string to RNA prop.
+	 * Should only be used in some functions' properties (currently only "text" one of funcs in UI API).
+	 */
+	PROP_STRING_PY_TRANSLATE = (1 << 28),
+
 	/* need context for update function */
 	PROP_CONTEXT_UPDATE = (1 << 22),
 	PROP_CONTEXT_PROPERTY_UPDATE = (1 << 22) | (1 << 27),
diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index 4b512b650a5..605fb18d5aa 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -2444,7 +2444,6 @@ static const char *rna_property_subtypename(PropertySubType type)
 		case PROP_FILENAME: return "PROP_FILENAME";
 		case PROP_DIRPATH: return "PROP_DIRPATH";
 		case PROP_BYTESTRING: return "PROP_BYTESTRING";
-		case PROP_TRANSLATE: return "PROP_TRANSLATE";
 		case PROP_UNSIGNED: return "PROP_UNSIGNED";
 		case PROP_PERCENTAGE: return "PROP_PERCENTAGE";
 		case PROP_FACTOR: return "PROP_FACTOR";
diff --git a/source/blender/makesrna/intern/rna_define.c b/source/blender/makesrna/intern/rna_define.c
index b94d7eb691f..ac307139860 100644
--- a/source/blender/makesrna/intern/rna_define.c
+++ b/source/blender/makesrna/intern/rna_define.c
@@ -2534,13 +2534,14 @@ PropertyRNA *RNA_def_string_file_name(StructOrFunctionRNA *cont_, const char *id
 	return prop;
 }
 
-PropertyRNA *RNA_def_string_translate(StructOrFunctionRNA *cont_, const char *identifier, const char *default_value,
-                                      int maxlen, const char *ui_name, const char *ui_description)
+PropertyRNA *RNA_def_string_py_translate(StructOrFunctionRNA *cont_, const char *identifier, const char *default_value,
+                                         int maxlen, const char *ui_name, const char *ui_description)
 {
 	ContainerRNA *cont = cont_;
 	PropertyRNA *prop;
 
-	prop = RNA_def_property(cont, identifier, PROP_STRING, PROP_TRANSLATE);
+	prop = RNA_def_property(cont, identifier, PROP_STRING, PROP_NONE);
+	RNA_def_property_flag(prop, PROP_STRING_PY_TRANSLATE);
 	if (maxlen != 0) RNA_def_property_string_maxlength(prop, maxlen);
 	if (default_value) RNA_def_property_string_default(prop, default_value);
 	RNA_def_property_ui_text(prop, ui_name, ui_description);
diff --git a/source/blender/makesrna/intern/rna_rna.c b/source/blender/makesrna/intern/rna_rna.c
index f86f6010e27..b5b3897ed46 100644
--- a/source/blender/makesrna/intern/rna_rna.c
+++ b/source/blender/makesrna/intern/rna_rna.c
@@ -46,6 +46,9 @@ EnumPropertyItem property_type_items[] = {
 	{0, NULL, 0, NULL, NULL}
 };
 
+/* XXX Keep in sync with bpy_props.c's property_subtype_xxx_items ???
+ *     Currently it is not...
+ */
 EnumPropertyItem property_subtype_items[] = {
 	{PROP_NONE, "NONE", 0, "None", ""},
 
@@ -53,7 +56,7 @@ EnumPropertyItem property_subtype_items[] = {
 	{PROP_FILEPATH, "FILEPATH", 0, "File Path", ""},
 	{PROP_DIRPATH, "DIRPATH", 0, "Directory Path", ""},
 	{PROP_FILENAME, "FILENAME", 0, "File Name", ""},
-	{PROP_TRANSLATE, "TRANSLATE", 0, "Translate", ""},
+	{PROP_PASSWORD, "PASSWORD", 0, "Password", "A string that is displayed hidden ('********')"},
 
 	/* numbers */
 	{PROP_UNSIGNED, "UNSIGNED", 0, "Unsigned", ""},
diff --git a/source/blender/makesrna/intern/rna_ui.c b/source/blender/makesrna/intern/rna_ui.c
index 00124a82dd1..fad93ea9054 100644
--- a/source/blender/makesrna/intern/rna_ui.c
+++ b/source/blender/makesrna/intern/rna_ui.c
@@ -813,9 +813,6 @@ static void rna_def_panel(BlenderRNA *brna)
 	                         "class name is \"OBJECT_PT_hello\", and bl_idname is not set by the "
 	                         "script, then bl_idname = \"OBJECT_PT_hello\"");
 
-	/* panel's label indeed doesn't need PROP_TRANSLATE flag: translation of label happens in runtime
-	 * when drawing panel and having this flag set will make runtime switching of language much more tricky
-	 * because label will be stored translated */
 	prop = RNA_def_property(srna, "bl_label", PROP_STRING, PROP_NONE);
 	RNA_def_property_string_sdna(prop, NULL, "type->label");
 	RNA_def_property_flag(prop, PROP_REGISTER);
@@ -992,9 +989,6 @@ static void rna_def_menu(BlenderRNA *brna)
 	                         "class name is \"OBJECT_MT_hello\", and bl_idname is not set by the "
 	                         "script, then bl_idname = \"OBJECT_MT_hello\")");
 
-	/* menu's label indeed doesn't need PROP_TRANSLATE flag: translation of label happens in runtime
-	 * when drawing panel and having this flag set will make runtime switching of language much more tricky
-	 * because label will be stored translated */
 	prop = RNA_def_property(srna, "bl_label", PROP_STRING, PROP_NONE);
 	RNA_def_property_string_sdna(prop, NULL, "type->label");
 	RNA_def_property_flag(prop, PROP_REGISTER);
diff --git a/source/blender/makesrna/intern/rna_ui_api.c b/source/blender/makesrna/intern/rna_ui_api.c
index 366d0dc1fd9..93410383a58 100644
--- a/source/blender/makesrna/intern/rna_ui_api.c
+++ b/source/blender/makesrna/intern/rna_ui_api.c
@@ -196,7 +196,7 @@ static void api_ui_item_common(FunctionRNA *func)
 {
 	PropertyRNA *prop;
 
-	RNA_def_string_translate(func, "text", "", 0, "", "Override automatic text of the item");
+	RNA_def_string_py_translate(func, "text", "", 0, "", "Override automatic text of the item");
 
 	prop = RNA_def_property(func, "icon", PROP_ENUM, PROP_NONE);
 	RNA_def_property_enum_items(prop, icon_items);
@@ -466,7 +466,7 @@ void RNA_api_ui_layout(StructRNA *srna)
 	parm = RNA_def_string(func, "type_property", "", 0, "",
 	                      "Identifier of property in data giving the type of the ID-blocks to use");
 	RNA_def_property_flag(parm, PROP_REQUIRED);
-	RNA_def_string_translate(func, "text", "", 0, "", "Custom label to display in UI");
+	RNA_def_string_py_translate(func, "text", "", 0, "", "Custom label to display in UI");
 	
 	func = RNA_def_function(srna, "template_path_builder", "uiTemplatePathBuilder");
 	parm = RNA_def_pointer(func, "data", "AnyType", "", "Data from which to take property");
@@ -475,7 +475,7 @@ void RNA_api_ui_layout(StructRNA *srna)
 	RNA_def_property_flag(parm, PROP_REQUIRED);
 	parm = RNA_def_pointer(func, "root", "ID", "", "ID-block from which path is evaluated from");
 	RNA_def_property_flag(parm, PROP_REQUIRED | PROP_RNAPTR);
-	RNA_def_string_translate(func, "text", "", 0, "", "Custom label to display in UI");
+	RNA_def_string_py_translate(func, "text", "", 0, "", "Custom label to display in UI");
 	
 	func = RNA_def_function(srna, "template_modifier", "uiTemplateModifier");
 	RNA_def_function_flag(func, FUNC_USE_CONTEXT);
diff --git a/source/blender/makesrna/intern/rna_wm.c b/source/blender/makesrna/intern/rna_wm.c
index f416d3403ad..c0fb2a7238f 100644
--- a/source/blender/makesrna/intern/rna_wm.c
+++ b/source/blender/makesrna/intern/rna_wm.c
@@ -1330,9 +1330,6 @@ static void rna_def_operator(BlenderRNA *brna)
 	RNA_def_property_flag(prop, PROP_REGISTER | PROP_NEVER_CLAMP);
 	RNA_def_struct_name_property(srna, prop);
 
-	/* operator's label indeed doesn't need PROP_TRANSLATE flag: translation of label happens in runtime
-	 * when drawing panel and having this flag set will make runtime switching of language much more tricky
-	 * because label will be stored translated */
 	prop = RNA_def_property(srna, "bl_label", PROP_STRING, PROP_NONE);
 	RNA_def_property_string_sdna(prop, NULL, "type->name");
 	RNA_def_property_string_maxlength(prop, RNA_DYN_DESCR_MAX); /* else it uses the pointer size! */
@@ -1397,9 +1394,6 @@ static void rna_def_macro_operator(BlenderRNA *brna)
 	RNA_def_property_flag(prop, PROP_REGISTER | PROP_NEVER_CLAMP);
 	RNA_def_struct_name_property(srna, prop);
 
-	/* menu's label indeed doesn't need PROP_TRANSLATE flag: translation of label happens in runtime
-	 * when drawing panel and having this flag set will make runtime switching of language much more tricky
-	 * because label will be stored translated */
 	prop = RNA_def_property(srna, "bl_label", PROP_STRING, PROP_NONE);
 	RNA_def_property_string_sdna(prop, NULL, "type->name");
 	RNA_def_property_string_maxlength(prop, RNA_DYN_DESCR_MAX); /* else it uses the pointer size! */