ENH: i18n: Add support for generating translation templates

This commit adds GenerateSlicerTranslationTemplates target allowing to
generate "<BaseName>_untranslated.ts" files.

To facilitate their distribution, the files are generated in the directory
"<CMAKE_BINARY_DIR>/TranslationTemplates".

Author: jcfr

CMake/SlicerMacroTranslation.cmake

@@ -67,7 +67,7 @@ function(SlicerMacroTranslation)
   foreach(language ${MY_TS_LANGUAGES})
     set(ts_file "${MY_TS_DIR}/${MY_TS_BASEFILENAME}_${language}.ts")
 
-    if(NOT Slicer_UPDATE_TRANSLATION AND NOT EXISTS ${ts_file})
+    if(NOT EXISTS ${ts_file})
       continue()
     endif()
 
@@ -79,6 +79,7 @@ function(SlicerMacroTranslation)
   # ---------------------------------------------------------------------------------
   set_property(GLOBAL APPEND PROPERTY Slicer_TS_BASEFILENAMES ${MY_TS_BASEFILENAME})
   set_property(GLOBAL PROPERTY Slicer_${MY_TS_BASEFILENAME}_FILES_TO_TRANSLATE "${FILES_TO_TRANSLATE}")
+  set_property(GLOBAL PROPERTY Slicer_${MY_TS_BASEFILENAME}_TS_DIR "${MY_TS_DIR}")
   set_property(GLOBAL PROPERTY Slicer_${MY_TS_BASEFILENAME}_TS_FILES "${TS_FILES}")
   set_property(GLOBAL PROPERTY Slicer_${MY_TS_BASEFILENAME}_QM_OUTPUT_DIR "${CMAKE_CURRENT_BINARY_DIR}")
 
@@ -108,13 +109,15 @@ function(SlicerFunctionAddGenerateSlicerTranslationQMFilesTarget)
 
   # ---------------------------------------------------------------------------------
   set(qm_output_dirs)
+  set(untranslated_ts_files)
 
   # ---------------------------------------------------------------------------------
   # UPDATE or ADD translation
   # ---------------------------------------------------------------------------------
   get_property(ts_basefilenames GLOBAL PROPERTY Slicer_TS_BASEFILENAMES)
   foreach(ts_basefilename IN LISTS ts_basefilenames)
     get_property(files_to_translate GLOBAL PROPERTY Slicer_${ts_basefilename}_FILES_TO_TRANSLATE)
+    get_property(ts_dir GLOBAL PROPERTY Slicer_${ts_basefilename}_TS_DIR)
     get_property(ts_files GLOBAL PROPERTY Slicer_${ts_basefilename}_TS_FILES)
     get_property(qm_output_dir GLOBAL PROPERTY Slicer_${ts_basefilename}_QM_OUTPUT_DIR)
 
@@ -147,8 +150,15 @@ function(SlicerFunctionAddGenerateSlicerTranslationQMFilesTarget)
       endforeach()
     endif()
 
-    set_source_files_properties(${ts_files} PROPERTIES OUTPUT_LOCATION ${qm_output_dir})
+    # Add custom commands for creating or updating "*_untranslated.ts" files.
+    set(untranslated_ts_dir "${CMAKE_BINARY_DIR}/TranslationTemplates")
+    set(untranslated_ts_file ${untranslated_ts_dir}/${ts_basefilename}_untranslated.ts)
+    SLICER_CREATE_TRANSLATION_ONLY(
+      ${srcs_to_translate} ${rewritten_scripts_to_translate_for_context} ${untranslated_ts_file}
+      OPTIONS -source-language en_US -no-ui-lines
+      )
 
+    set_source_files_properties(${ts_files} PROPERTIES OUTPUT_LOCATION ${qm_output_dir})
     if(Slicer_UPDATE_TRANSLATION)
       # Add custom command for creating or updating "*_<lang>.ts" translation files, and for
       # generating the associated "*_<lang>.qm" files.
@@ -161,13 +171,22 @@ function(SlicerFunctionAddGenerateSlicerTranslationQMFilesTarget)
       QT5_ADD_TRANSLATION(QM_OUTPUT_FILES ${ts_files})
     endif()
 
+    list(APPEND untranslated_ts_files ${untranslated_ts_file})
     list(APPEND qm_output_dirs ${qm_output_dir})
   endforeach()
 
   # ---------------------------------------------------------------------------------
   # Targets
   # ---------------------------------------------------------------------------------
 
+  set(_all)
+  if(Slicer_UPDATE_TRANSLATION)
+    set(_all ALL)
+  endif()
+  add_custom_target(GenerateSlicerTranslationTemplates ${_all} DEPENDS
+    ${untranslated_ts_files}
+    )
+
   add_custom_target(GenerateSlicerTranslationQMFiles ALL DEPENDS
     ${QM_OUTPUT_FILES}
     )
@@ -187,3 +206,53 @@ function(SlicerFunctionAddGenerateSlicerTranslationQMFilesTarget)
   set(${MY_QM_OUTPUT_DIRS_VAR} ${qm_output_dirs} PARENT_SCOPE)
 
 endfunction()
+
+
+function(SLICER_CREATE_TRANSLATION_ONLY)
+  # Adapted from QT5_CREATE_TRANSLATION:
+  # - remove call to "qt5_add_translation"
+  # - remove setting of "_qm_files" output variable
+  set(options)
+  set(oneValueArgs)
+  set(multiValueArgs OPTIONS)
+
+  cmake_parse_arguments(_LUPDATE "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+  set(_lupdate_files ${_LUPDATE_UNPARSED_ARGUMENTS})
+  set(_lupdate_options ${_LUPDATE_OPTIONS})
+
+  set(_my_sources)
+  set(_my_tsfiles)
+  foreach(_file ${_lupdate_files})
+    get_filename_component(_ext ${_file} EXT)
+    get_filename_component(_abs_FILE ${_file} ABSOLUTE)
+    if(_ext MATCHES "ts")
+        list(APPEND _my_tsfiles ${_abs_FILE})
+    else()
+        list(APPEND _my_sources ${_abs_FILE})
+    endif()
+  endforeach()
+  foreach(_ts_file ${_my_tsfiles})
+    if(_my_sources)
+      # make a list file to call lupdate on, so we don't make our commands too
+      # long for some systems
+      get_filename_component(_ts_name ${_ts_file} NAME_WE)
+      set(_ts_lst_file "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/${_ts_name}_lst_file")
+      set(_lst_file_srcs)
+      foreach(_lst_file_src ${_my_sources})
+          set(_lst_file_srcs "${_lst_file_src}\n${_lst_file_srcs}")
+      endforeach()
+
+      get_directory_property(_inc_DIRS INCLUDE_DIRECTORIES)
+      foreach(_pro_include ${_inc_DIRS})
+          get_filename_component(_abs_include "${_pro_include}" ABSOLUTE)
+          set(_lst_file_srcs "-I${_pro_include}\n${_lst_file_srcs}")
+      endforeach()
+
+      file(WRITE ${_ts_lst_file} "${_lst_file_srcs}")
+    endif()
+    add_custom_command(OUTPUT ${_ts_file}
+        COMMAND ${Qt5_LUPDATE_EXECUTABLE}
+        ARGS ${_lupdate_options} "@${_ts_lst_file}" -ts ${_ts_file}
+        DEPENDS ${_my_sources} ${_ts_lst_file} VERBATIM)
+  endforeach()
+endfunction()