Use already existing system preference and created accessor rather than hard...

Use already existing system preference and created accessor rather than hard coded value which was different from
default for the system preference
This can lead to different cache ids generated for same content by different
parts of the code -> duplication of same data in cache backend.

product/ERP5/Document/Document.py

@@ -75,8 +75,8 @@ VALID_TRANSPARENT_IMAGE_FORMAT_LIST = ('png', 'gif', 'tiff', 'svg')
 DEFAULT_DISPLAY_ID_LIST = ('nano', 'micro', 'thumbnail',
                             'xsmall', 'small', 'medium',
                             'large', 'xlarge',)
-# default image quality
-DEFAULT_IMAGE_QUALITY = 75
+# default image qualitay (obsoleted use getPreferredImageQuality on a portal_preferences tool)
+DEFAULT_IMAGE_QUALITY = 75.0
 
 DEFAULT_CONTENT_TYPE = 'text/html'
 

product/ERP5/Document/Image.py

@@ -45,7 +45,7 @@ from Products.ERP5Type.Utils import fill_args_from_request
 from Products.ERP5.Document.File import File
 from Products.ERP5.Document.Document import Document, ConversionError,\
                      VALID_TEXT_FORMAT_LIST, VALID_TRANSPARENT_IMAGE_FORMAT_LIST,\
-                     DEFAULT_DISPLAY_ID_LIST, DEFAULT_IMAGE_QUALITY, _MARKER
+                     DEFAULT_DISPLAY_ID_LIST, _MARKER
 from os.path import splitext
 from OFS.Image import Image as OFSImage
 from OFS.Image import getImageInfo
@@ -58,7 +58,7 @@ from Products.ERP5.mixin.text_convertable import TextConvertableMixin
 
 def getDefaultImageQuality(portal, format=None):
   preference_tool = portal.portal_preferences
-  return preference_tool.getPreference('preferred_image_quality', DEFAULT_IMAGE_QUALITY)
+  return preference_tool.getPreferredImageQuality()
 
 class Image(TextConvertableMixin, File, OFSImage):
   """