GRN2-134: Added Color Input for lighten and darken (#529)

* Added Color Input for lighten and darken

* rspec

app/controllers/concerns/themer.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+# BigBlueButton open source conferencing system - http://www.bigbluebutton.org/.
+#
+# Copyright (c) 2018 BigBlueButton Inc. and by respective authors (see below).
+#
+# This program is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free Software
+# Foundation; either version 3.0 of the License, or (at your option) any later
+# version.
+#
+# BigBlueButton 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 Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
+
+module Themer
+extend ActiveSupport::Concern
+
+# Lightens a color by 40%
+def color_lighten(color)
+  # Uses the built in Sass Engine to lighten the color
+
+  dummy_scss = "h1 { color: $lighten; }"
+  compiled = Sass::Engine.new("$lighten:lighten(#{color}, 40%);" + dummy_scss, syntax: :scss).render
+
+  string_locater = 'color: '
+  color_start = compiled.index(string_locater) + string_locater.length
+
+  compiled[color_start..color_start + 6]
+end
+
+# Darkens a color by 10%
+def color_darken(color)
+  # Uses the built in Sass Engine to darken the color
+
+  dummy_scss = "h1 { color: $darken; }"
+  compiled = Sass::Engine.new("$darken:darken(#{color}, 10%);" + dummy_scss, syntax: :scss).render
+
+  string_locater = 'color: '
+  color_start = compiled.index(string_locater) + string_locater.length
+
+  compiled[color_start..color_start + 6]
+end
+end