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# frozen_string_literal: true
# Copyright (C) 2019 Miquel Sabaté Solà <mikisabate@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
module Jekyll
# Render the OG image meta HTML tag for the currently rendered page.
class RenderOGImageTag < Liquid::Tag
# The path to be used when the current page does not have a specific image.
DEFAULT_PATH = "/images/default.png"
def render(context)
img = normalize(context["raw_title"]) + ".png"
path = image_exists?(img) ? "/images/posts/#{img}" : DEFAULT_PATH
render_meta("og:image", "http://jo.mssola.com#{path}") +
render_meta("og:image:width", 630) +
render_meta("og:image:height", 315) +
render_meta("twitter:image", "http://jo.mssola.com#{path}", name: true)
end
protected
# Returns true if the given image exists inside of /images/posts.
def image_exists?(image)
return false if image == ".png"
path = File.expand_path(File.join(File.dirname(__FILE__), "..", "images", "posts", image))
File.file?(path)
end
# Downcases the given string and replaces space characters with "-"
def normalize(str)
str.gsub(/\s/, "-").downcase
end
# Render an HTML meta tag with the given property and content
# attributes. You may optionally pass a `name` argument. When true, it will
# use "name" instead of "property". Defaults to nil.
def render_meta(property, content, name: nil)
if name
"<meta name=\"#{property}\" content=\"#{content}\" />"
else
"<meta property=\"#{property}\" content=\"#{content}\" />"
end
end
end
end
Liquid::Template.register_tag("render_og_image", Jekyll::RenderOGImageTag)
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