feat: add translation context for operators and their properties.

- add translation context for operator, menu, panel and etc. and their associated properties.
- improve some name and description but not finished.
- move reset BME material function inside BMEMaterialsHelper.
- rename variable of collection visitor in BME adder operator for clear meaning.
- replace some message box to report in ballance elements reset operator, BME materials reset operator and rail UV operator

bbp_ng/UTIL_translation.py

@@ -0,0 +1,87 @@
+import bpy
+
+#region Translation Contexts
+
+## NOTE: Translation Priniciple
+#  Due to the shitty design of Blender I18N tools (I can't specify context for every translation entries and its static analyse is so bad),
+#  I will specify all context but I can't do anything if Blender throw my translation context away.
+#  
+#  BME module has its own context naming convention which make sure all configuration fields of prototypes are properly translated.
+#  This module also provide a corresponding function to compute these context string from given BME prototype name and the index of configuration fields.
+#  
+#  For BBP plugin self, there is a priniciple list which you should follow when providing translation context.
+#  - For operator, menu, panel and etc, set their `bl_translation_context` to their names, such as `BBP_OT_some_operator`
+#  - For property located in operator, menu, panel and etc, set their `translation_context` to corresponding class name, 
+#    plus `/property` suffix, such as `BBP_OT_some_operator/property`.
+#  - For draw function located in operator, menu, panel and etc, set their `translation_context` to corresponding class name, 
+#    plus `/draw` suffix, such as `BBP_OT_some_operator/draw`.
+#  - For property loacted in shared class (usually shared by multiple operators), set their `translation_context` to `BME/<MODULE_NAME>.<CLASS_NAME>/property`.
+#    `<MODULE_NAME>` is the module name (file name) where this class located. `<CLASS_NAME>` is the name of this class.
+#    For example, `BBP/some_module.some_class/property`
+#    
+#  Due to the shitty design, I can't find a way to add translation context for descrption field.
+#  So these description may collide with Blender official translation and thus not put in result file.
+#  I have no idea about this.
+#  
+#  Due to the shitty static analyse ability of Blender I18N plugin, all context should be written in literal,
+#  not the reference to other fields or the return value of some function.
+#  However for those strings, which originally should not be extracted by Blender I18N plugin, the way to get their context string is free.
+#  
+#  
+#  For the string given to Python `print()` which will be output in console,
+#  please use `bpy.app.translations.pgettext_rpt()` to get translation message because they are report.
+#  For the string given to `UTIL_functions.message_box()`, please use `bpy.app.translations.pgettext_iface` because they are UI elements.
+#  
+#  It seema that `bpy.app.translations.pgettext` function family has fatal error when extracting message with context
+#  (it will produce a correct one and a wrong one which just simply concat the message and its context. I don't know why).
+#  
+#  
+#  All translation annotation are started with `TR:`
+#  
+
+# The universal translation context prefix for BBP_NG plugin.
+CTX_BBP: str = 'BBP'
+
+# The universal translation context prefix for BME module in BBP_NG plugin.
+CTX_BBP_BME: str = CTX_BBP + '/BME'
+def build_prototype_showcase_context(identifier: str) -> str:
+    """
+    Build the context for getting the translation for BME prototype showcase title.
+    @param[in] identifier The identifier of this prototype.
+    @return The context for getting translation.
+    """
+    return CTX_BBP_BME + '/' + identifier
+def build_prototype_showcase_cfg_context(identifier: str, cfg_index: int) -> str:
+    """
+    Build the context for getting the translation for BME prototype showcase configuration title or description.
+    @param[in] identifier The identifier of this prototype.
+    @param[in] cfg_index The index of this configuration in this prototype showcase.
+    @return The context for getting translation.
+    """
+    return CTX_BBP_BME + f'/{identifier}/[{cfg_index}]'
+
+#endregion
+
+# ##### BEGIN AUTOGENERATED I18N SECTION #####
+# NOTE: You can safely move around this auto-generated block (with the begin/end markers!),
+#       and edit the translations by hand.
+#       Just carefully respect the format of the tuple!
+
+# Tuple of tuples:
+# ((msgctxt, msgid), (sources, gen_comments), (lang, translation, (is_fuzzy, comments)), ...)
+translations_tuple = ()
+
+translations_dict = {}
+for msg in translations_tuple:
+    key = msg[0]
+    for lang, trans, (is_fuzzy, comments) in msg[2:]:
+        if trans and not is_fuzzy:
+            translations_dict.setdefault(lang, {})[key] = trans
+
+# ##### END AUTOGENERATED I18N SECTION #####
+
+def register() -> None:
+    bpy.app.translations.register(__package__, translations_dict)
+
+def unregister() -> None:
+    bpy.app.translations.unregister(__package__)