def _generate_srcset_attribute(self,
breakpoints,
transformation=None,
**options):
"""
Helper function. Generates srcset attribute value of the HTML img tag.
:param breakpoints: A list of breakpoints.
:param transformation: Custom transformation
:param options: Additional options
:return: Resulting srcset attribute value
:raises ValueError: In case of invalid or missing parameters
"""
if not breakpoints:
return None
if transformation is None:
transformation = dict()
return ", ".join([
"{0} {1}w".format(
utils.cloudinary_scaled_url(self.public_id, w, transformation,
options), w) for w in breakpoints
])
def _fetch_breakpoints(self, srcset_data=None, **options):
"""
Helper function. Retrieves responsive breakpoints list from cloudinary server
When passing special string to transformation `width` parameter of form `auto:breakpoints{parameters}:json`,
the response contains JSON with data of the responsive breakpoints
:param srcset_data: A dictionary containing the following keys:
min_width Minimal width of the srcset images
max_width Maximal width of the srcset images
bytes_step Minimal bytes step between images
max_images Number of srcset images to generate
:param options: Additional options
:return: Resulting breakpoints
"""
if srcset_data is None:
srcset_data = dict()
min_width = srcset_data.get("min_width", 50)
max_width = srcset_data.get("max_width", 1000)
bytes_step = srcset_data.get("bytes_step", 20000)
max_images = srcset_data.get("max_images", 20)
transformation = srcset_data.get("transformation")
kbytes_step = int(ceil(float(bytes_step) / 1024))
breakpoints_width_param = "auto:breakpoints_{min_width}_{max_width}_{kbytes_step}_{max_images}:json".format(
min_width=min_width, max_width=max_width, kbytes_step=kbytes_step, max_images=max_images)
breakpoints_url = utils.cloudinary_scaled_url(self.public_id, breakpoints_width_param, transformation, options)
return _http_client.get_json(breakpoints_url).get("breakpoints", None)
