Load the converter class on demand

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

HISTORY.rst

@@ -172,6 +172,7 @@
   add_to_object.
 * Rename transformation manager method get_for_model to
   get_for_object.
+* Load the converter class on demand.
 
 3.1.11 (2019-04-XX)
 ===================

docs/releases/3.2.rst

@@ -204,6 +204,7 @@ Other changes
   add_to_object.
 * Rename transformation manager method get_for_model to
   get_for_object.
+* Load the converter class on demand.
 
 Removals
 --------

mayan/apps/converter/__init__.py

@@ -1,6 +1,5 @@
 from __future__ import unicode_literals
 
-from .runtime import converter_class  # NOQA
 from .transformations import (  # NOQA
     BaseTransformation, TransformationResize, TransformationRotate,
     TransformationZoom

mayan/apps/converter/runtime.py

@@ -1,9 +0,0 @@
-from __future__ import unicode_literals
-
-from django.utils.module_loading import import_string
-
-from .settings import setting_graphics_backend
-
-backend = converter_class = import_string(
-    dotted_path=setting_graphics_backend.value
-)

mayan/apps/converter/utils.py

@@ -0,0 +1,13 @@
+from __future__ import unicode_literals
+
+import logging
+
+from django.utils.module_loading import import_string
+
+from .settings import setting_graphics_backend
+
+logger = logging.getLogger(__name__)
+
+
+def get_converter_class():
+    return import_string(dotted_path=setting_graphics_backend.value)

mayan/apps/documents/models/document_page_models.py

@@ -11,11 +11,12 @@ from django.utils.encoding import force_text, python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
 
 from mayan.apps.converter import (
-    converter_class, BaseTransformation, TransformationResize,
-    TransformationRotate, TransformationZoom
+    BaseTransformation, TransformationResize, TransformationRotate,
+    TransformationZoom
 )
 from mayan.apps.converter.literals import DEFAULT_ZOOM_LEVEL, DEFAULT_ROTATION
 from mayan.apps.converter.models import Transformation
+from mayan.apps.converter.utils import get_converter_class
 
 from ..managers import DocumentPageCachedImage, DocumentPageManager
 from ..settings import (
@@ -71,7 +72,7 @@ class DocumentPage(models.Model):
 
     def detect_orientation(self):
         with self.document_version.open() as file_object:
-            converter = converter_class(
+            converter = get_converter_class()(
                 file_object=file_object,
                 mime_type=self.document_version.mimetype
             )
@@ -193,7 +194,7 @@ class DocumentPage(models.Model):
 
         if not setting_disable_base_image_cache.value and storage_documentimagecache.exists(cache_filename):
             logger.debug('Page cache file "%s" found', cache_filename)
-            converter = converter_class(
+            converter = get_converter_class()(
                 file_object=storage_documentimagecache.open(cache_filename)
             )
 
@@ -202,7 +203,7 @@ class DocumentPage(models.Model):
             logger.debug('Page cache file "%s" not found', cache_filename)
 
             try:
-                converter = converter_class(
+                converter = get_converter_class()(
                     file_object=self.document_version.get_intermidiate_file()
                 )
                 converter.seek(page_number=self.page_number - 1)

mayan/apps/documents/models/document_version_models.py

@@ -12,9 +12,10 @@ from django.urls import reverse
 from django.utils.encoding import force_text, python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
 
-from mayan.apps.converter import converter_class, TransformationRotate
+from mayan.apps.converter import TransformationRotate
 from mayan.apps.converter.exceptions import InvalidOfficeFormat, PageCountError
 from mayan.apps.converter.models import Transformation
+from mayan.apps.converter.utils import get_converter_class
 from mayan.apps.mimetype.api import get_mimetype
 
 from ..events import event_document_new_version, event_document_version_revert
@@ -168,7 +169,7 @@ class DocumentVersion(models.Model):
             logger.debug('Intermidiate file "%s" not found.', cache_filename)
 
             try:
-                converter = converter_class(file_object=self.open())
+                converter = get_converter_class()(file_object=self.open())
                 pdf_file_object = converter.to_pdf()
 
                 with storage_documentimagecache.open(cache_filename, mode='wb+') as file_object:
@@ -382,7 +383,7 @@ class DocumentVersion(models.Model):
     def update_page_count(self, save=True):
         try:
             with self.open() as file_object:
-                converter = converter_class(
+                converter = get_converter_class()(
                     file_object=file_object, mime_type=self.mimetype
                 )
                 detected_pages = converter.get_page_count()

mayan/apps/ocr/classes.py

@@ -1,6 +1,6 @@
 from __future__ import unicode_literals
 
-from mayan.apps.converter import converter_class
+from mayan.apps.converter.utils import get_converter_class
 
 
 class OCRBackendBase(object):
@@ -10,7 +10,7 @@ class OCRBackendBase(object):
         if not transformations:
             transformations = []
 
-        self.converter = converter_class(file_object=file_object)
+        self.converter = get_converter_class()(file_object=file_object)
 
         for transformation in transformations:
             self.converter.transform(transformation=transformation)

mayan/apps/sources/classes.py

@@ -13,7 +13,8 @@ from django.urls import reverse
 from django.utils.encoding import force_text, python_2_unicode_compatible
 from django.utils.six.moves.urllib.parse import quote_plus, unquote_plus
 
-from mayan.apps.converter import TransformationResize, converter_class
+from mayan.apps.converter import TransformationResize
+from mayan.apps.converter.utils import get_converter_class
 
 from .storages import storage_staging_file_image_cache
 
@@ -143,7 +144,7 @@ class StagingFile(object):
 
         try:
             file_object = open(self.get_full_path(), mode='rb')
-            converter = converter_class(file_object=file_object)
+            converter = get_converter_class()(file_object=file_object)
 
             page_image = converter.get_page()