config.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * TEN Theme based on NCM boost theme.
 *
 * @package   theme_ten
 * @copyright 2019 Nicolas Jourdain
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

// This line protects the file from being accessed by a URL directly.
defined('MOODLE_INTERNAL') || die();

// THEME variable is defined before this page is included and we can define settings by adding properties to this global object.

// The first setting we need is the name of the theme. This should be the last part of the component name, and the same
// as the directory name for our theme.
$THEME->name = 'ten';

// This setting list the style sheets we want to include in our theme. Because we want to use SCSS instead of CSS - we won't
// list any style sheets. If we did we would list the name of a file in the /styles/ folder for our theme without any css file
// extensions.
$THEME->sheets = [];

// This is a setting that can be used to provide some styling to the content in the TinyMCE text editor. This is no longer the
// default text editor and "Atto" does not need this setting so we won't provide anything. If we did it would work the same
// as the previous setting - listing a file in the /styles/ folder.
$THEME->editor_sheets = [];

// This is a critical setting. We want to inherit from theme_boost because it provides a great starting point for SCSS bootstrap4
// themes. We could add more than one parent here to inherit from multiple parents, and if we did they would be processed in
// order of importance (later themes overriding earlier ones). Things we will inherit from the parent theme include
// styles and mustache templates and some (not all) settings.
$THEME->parents = ['boost', 'ncmboost'];

// A dock is a way to take blocks out of the page and put them in a persistent floating area on the side of the page. Boost
// does not support a dock so we won't either - but look at bootstrapbase for an example of a theme with a dock.
$THEME->enable_dock = false;

$THEME->prescsscallback = 'theme_ten_get_pre_scss';

// This is an old setting used to load specific CSS for some YUI JS. We don't need it in Boost based themes because Boost
// provides default styling for the YUI modules that we use. It is not recommended to use this setting anymore.
$THEME->yuicssmodules = array();

// Most themes will use this rendererfactory as this is the one that allows the theme to override any other renderer.
$THEME->rendererfactory = 'theme_overridden_renderer_factory';

// This is a list of blocks that are required to exist on all pages for this theme to function correctly. For example
// bootstrap base requires the settings and navigation blocks because otherwise there would be no way to navigate to all the
// pages in Moodle. Boost does not require these blocks because it provides other ways to navigate built into the theme.
$THEME->requiredblocks = '';

// This is a feature that tells the blocks library not to use the "Add a block" block. We don't want this in boost based themes
// because it forces a block region into the page when editing is enabled and it takes up too much room.
$THEME->addblockposition = BLOCK_ADDBLOCK_POSITION_FLATNAV;
// This is the function that returns the SCSS source for the main file in our theme. We override the boost version because
// we want to allow presets uploaded to our own theme file area to be selected in the preset list.
$THEME->scss = function($theme) {
    // We need to load the config for our parent theme because that is where the preset setting is defined.
    $parentconfig = theme_config::load('ncmboost');
    // Call a function from our parent themes lib.php file to fetch the content of the themes main SCSS file
    // based on it's own config, not ours.
    return theme_ncmboost_get_main_scss_content($parentconfig);
};