def ThemeVocabulary(context):
"""Vocabulary factory for theme options."""
return SimpleVocabulary(
[
SimpleTerm(value=u"light", title=_(u"Light")),
SimpleTerm(value=u"dark", title=_(u"Dark")),
SimpleTerm(value=u"custom", title=_(u"Custom")),
]
)
def validate_base_image(value):
"""Validate the base image used to create featured image.
The image must follow these specifications:
* .png format
* be at least 1200 x 630 pixels
* should be smaller that 1MB
:param value: Image encoded into base64 to be validated
:type value: string
:raises:
:class:`~zope.interface.Invalid` if the image is not valid
"""
if not value:
return False
filename, data = b64decode_file(value)
# check size
if len(data) > 1048576:
raise Invalid(_(u'Image should be smaller than 1MB.'))
img = Image.open(StringIO(data))
# check format
if img.format != 'PNG':
raise Invalid(_(u'Image should be in PNG format.'))
# check image dimensions
width, height = img.size
if not(width >= 1200 and height >= 630):
raise Invalid(_(
u'Image must be at least 1200 x 630 pixels for the best display on high resolution devices.'
))
return True
