wagtailimages_tags.py 文件源码

def render(self, context):
        try:
            image = self.image_expr.resolve(context)
        except template.VariableDoesNotExist:
            return ''

        if not image:
            return ''

        rendition = get_rendition_or_not_found(image, self.filter)

        if self.output_var_name:
            # return the rendition object in the given variable
            context[self.output_var_name] = rendition
            return ''
        else:
            # render the rendition's image tag now
            resolved_attrs = {}
            for key in self.attrs:
                resolved_attrs[key] = self.attrs[key].resolve(context)
            return rendition.img_tag(resolved_attrs)