class Sample_Radio_Image_Control extends WP_Customize_Control {

    public $type = 'radio-image';

    public function render_content() {

      if ( empty( $this->choices ) )
        return;

      $name = '_customize-radio-' . $this->id;

      ?>
      <style>
        input.stylish-radio-image {
            display: none;
        }
        input.stylish-radio-image + span {
            margin-right: 10px;
            display: inline-flex;
            padding: 2px!important;
            width: auto;
            height: auto;
            overflow: hidden;
            border: 2px solid #FFFFFF;
        }
        input.stylish-radio-image:checked + span {
            border: 2px solid #777777;
        }
      </style>
      <label>
        <span class="customize-control-title"><?php echo esc_html( $this->label ); ?></span>
        <?php foreach ( $this->choices as $value => $label ) : ?>
          <label>
            <input type="radio" value="<?php echo esc_attr( $value ); ?>" <?php $this->link(); checked( $this->value(), $value ); ?> class="stylish-radio-image" name="<?php echo esc_attr( $name ); ?>"/>
              <span><img src="<?php echo esc_url($label); ?>" alt="<?php echo esc_attr( $value ); ?>" /></span>
          </label>
          <?php endforeach; ?>
      </label>
      <?php
    }

  }