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from django import template |
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from wagtail.images.models import SourceImageIOError |
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from wagtail.images.shortcuts import get_rendition_or_not_found |
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from wagtail.images.templatetags.wagtailimages_tags import ImageNode |
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register = template.Library() |
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@register.tag(name="responsiveimage") |
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def responsiveimage(parser, token): |
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bits = token.split_contents()[1:] |
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image_var = bits[0] |
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filter_spec = bits[1] |
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bits = bits[2:] |
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if len(bits) == 2 and bits[0] == 'as': |
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# token is of the form {% responsiveimage self.photo max-320x200 as img %} |
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return ImageNode(image_var, filter_spec, output_var_name=bits[1]) |
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else: |
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# token is of the form {% responsiveimage self.photo max-320x200 %} - all additional tokens |
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# should be kwargs, which become attributes |
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attrs = {} |
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for bit in bits: |
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try: |
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name, value = bit.split('=') |
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except ValueError: |
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raise template.TemplateSyntaxError( |
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"""'responsiveimage' tag should be of the form |
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{% responsiveimage self.photo max-320x200 [ custom-attr=\"value\" ... ] %} or |
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{% responsiveimage self.photo max-320x200 as img %}""" |
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) |
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attrs[name] = parser.compile_filter(value) # setup to resolve context variables as value |
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return ResponsiveImageNode(image_var, filter_spec, attrs=attrs) |
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class ResponsiveImageNode(template.Node): |
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def __init__(self, image_var_name, filter_spec, output_var_name=None, attrs={}): |
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self.image_var = template.Variable(image_var_name) |
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self.output_var_name = output_var_name |
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self.attrs = attrs |
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self.filter_spec = filter_spec |
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def render(self, context): |
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try: |
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image = self.image_var.resolve(context) |
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except template.VariableDoesNotExist: |
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return '' |
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if not image: |
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return '' |
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Rendition = image.get_rendition_model() |
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rendition = get_rendition_or_not_found(image, self.filter_spec) |
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# Parse srcset format into array |
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try: |
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raw_sources = str(self.attrs['srcset']).replace('"', '').split(',') |
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srcset_renditions = [] |
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widths = [] |
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newsrcseturls = [] |
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for source in raw_sources: |
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flt = source.strip().split(' ')[0] |
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width = source.strip().split(' ')[1] |
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# cache widths to be re-appended after filter has been converted to URL |
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widths.append(width) |
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try: |
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srcset_renditions.append(image.get_rendition(flt)) |
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except SourceImageIOError: |
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tmprend = Rendition(image=image, width=0, height=0) |
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tmprend.file.name = 'not-found' |
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for index, rend in enumerate(srcset_renditions): |
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newsrcseturls.append(' '.join([rend.url, widths[index]])) |
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except KeyError: |
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newsrcseturls = [] |
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pass |
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if self.output_var_name: |
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# return the rendition object in the given variable |
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context[self.output_var_name] = rendition |
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return '' |
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else: |
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# render the rendition's image tag now |
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resolved_attrs = {} |
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for key in self.attrs: |
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if key == 'srcset': |
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resolved_attrs[key] = ','.join(newsrcseturls) |
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continue |
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resolved_attrs[key] = self.attrs[key].resolve(context) |
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return rendition.img_tag(resolved_attrs) |
