"Display Site Title and Tagline" checkbox not working?

Question

I'm trying to develop a theme. but "Display Site Title and Tagline" checkbox not working nothing change when i check or uncheck the site tile and tagline still exist. also the color option not giving any effect? please help my code for the header text is:

<header class="image-bg-fluid-height" id="startchange" style="background-image: url('<?php echo( get_header_image() ); ?>')" >

      <h1 class="h1-hdr"><?php bloginfo('name');?> </h1>
        <br/> <br/>
        <P id="header-pa"><?php bloginfo('description');?> </P>
        <a  class="btn btn-primary btn-lg outline " role="button" href="#" id="btn-header">WATCH A VIDEO</a>
        <br/> <br/> 
    </header>

Answer 1

this peace of code will help you

        <?php
            if (display_header_text()==true){
                echo '<h1>'.get_bloginfo( 'name' ) .'</h1>';
                echo '<h2>'.get_bloginfo('description').'</h2>';                            
            } else{
                  //do something
            }
          ?>

Answer 2

Above answers didn't work for me - this did. This displays the site description if the box is checked and there's text in the description field.

if ( (get_theme_mod('header_text') != 0) && (get_bloginfo('description') != '') ) {
  echo '<div class="site-description">' . get_bloginfo('description') . '</div>';
}

This is also useful if you're trying to customize the display based on the Customizer's settings:

var_dump(get_theme_mods());

Answer 3

The answer above didn't work for me. After examining the twenty seventeen theme I came up with this solution that worked for me. Add this to your wordpress theme page as appropriate.

<?php
        $site_description = get_bloginfo( 'description', 'display' );

        if ( $site_description || is_customize_preview() ) :
        ?>
          <h2 class="site-description"><?php echo $site_description; ?></h2>
        <?php endif; ?>

The CSS Class "site-description" can be defined by adding the following to your functions.php. Most sites have this set up already so if you are modifying a theme made by someone else it's worth looking for this to check the H2 Css Class name.

add_theme_support('custom-logo');

function yourPrefix_custom_logo_setup()
{
    $defaults = array(
        'height' => 207,
        'width' => 276,
        'flex-height' => false,
        'flex-width' => false,
        'header-text' => array('site-title', 'yourPrefix-site-description'),
    );
    add_theme_support('custom-logo', $defaults);
}
add_action('after_setup_theme', 'yourPrefix_custom_logo_setup');

You should change yourPrefix to whatever the prefix is for the theme that you are working on in order to prevent conflicts etc.