Wordpess_Theme_Options_Demo.php

<?php
/**
 * Plugin Name: p47 Options
 * Plugin URI: http://point47.com
 * Description: demo a options papge
 * Version: 1.0
 * Author: Sorin Gitlan
 * Author URI: http://point47.com
 *
 *  Use get_option('p47_plugin_options') in the template to access the saved variables.
 * 
 */

class P47_Options{

    public $options;

    public function __construct()
    {
        //delete_option('p47_plugin_options');
        //print_r( get_option('p47_plugin_options') );

        // get the saved options data
        $this->options = get_option('p47_plugin_options');

        $this->register_settings_and_fields();
    }

    // this is called STATIC
    public static function add_menu_page()
    {
        add_options_page( 'Theme Options', 'Theme Options', 'administrator', __FILE__, array('P47_Options', 'display_options_page'));
    }

    public function display_options_page()
    {
    ?>
        <div class="wrap">      
            <?php screen_icon(); ?>
            <h2>My Theme Options</h2>
            <form action="options.php" method="POST" enctype="multipart/form-data">
                <?php settings_fields( 'p47_plugin_options' ); ?>
                <?php do_settings_sections( __FILE__ ); ?>

                <p class="submit">
                    <button type="submit" class="button-primary">Save changes</button>
                </p>
            </form>
        </div>

    <?php
    }

    public function register_settings_and_fields()
    {
        // this registers and initializes the settings
        register_setting('p47_plugin_options', 'p47_plugin_options', array($this, 'p47_validate_settings') );
        
        // create a section of settings; params: id, title of section, callback, which page
        add_settings_section( 'p47_main_section', 'Main Settings', array($this, 'p47_main_section_cb'), __FILE__ );

        // register form fields
        add_settings_field( 'p47_banner_heading', 'Banner Heading: ', array($this, 'p47_banner_heading_setting'), __FILE__, 'p47_main_section' );
        add_settings_field( 'p47_logo', 'Your Logo: ', array($this, 'p47_logo_setting'), __FILE__, 'p47_main_section' );
        add_settings_field( 'p47_color_scheme', 'Your Desired Logo Scheme: ', array($this, 'p47_color_scheme_setting'), __FILE__, 'p47_main_section' );
    }

    public function p47_main_section_cb()
    {
        // optional    
    }

    public function p47_validate_settings( $plugin_options )
    {

        // TODO: test if the file is a image

        // upload the image
        if( !empty($_FILES['p47_logo_upload']['tmp_name']) ){
            $override = array('test_form' => false);
            $file = wp_handle_upload( $_FILES['p47_logo_upload'], $override );
            $plugin_options['p47_logo'] = $file['url'];
        } else {
            $plugin_options['p47_logo'] = $this->options['p47_logo'];
        }

        return $plugin_options;
    }


    /**
     * 
     * INPUTS
     * 
     */
    
    // BANNER Heading
    public function p47_banner_heading_setting()
    {
        echo '<input type="text" name="p47_plugin_options[p47_banner_heading]" value="'. $this->options['p47_banner_heading'] .'">';
    }

    // LOGO upload
    public function p47_logo_setting()
    {
        echo '<input type="file" name="p47_logo_upload"><br> <br>';
        if( isset($this->options['p47_logo']) ){
            echo '<img src="'.$this->options['p47_logo'].'" alt="">';
        }
    }

    public function p47_color_scheme_setting()
    {
        $items = array('Red', 'Blue', 'Green', 'Black', 'White', 'Yellow');
        echo '<select name="p47_plugin_options[p47_color_scheme]">';
        foreach ($items as $item) {
            $selected = ($this->options['p47_color_scheme'] === $item) ? 'selected="selected"' : '';
            echo '<option value="'.$item.'" '.$selected.'>'.$item.'</option>';
        }
        echo '</select>';
    }

}

// attach options page only after the admin menu was initiated
add_action( 'admin_menu', function(){
    P47_Options::add_menu_page();
});

add_action('admin_init', function(){
    new P47_Options();
});