Building a Custom Block Module with Configurable Text Display

1. Module Creation:

• Use Composer or Drush to create a new module:

  composer create-project drupal/recommended-project my_module

• Navigate to the module directory:

  cd my_module

2. Block Class:

• Create src/Plugin/Block/CustomTextBlock.php:

<?php

namespace Drupal\my_module\Plugin\Block;

use Drupal\Core\Block\BlockBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Provides a 'Custom Text Block' block.
 *
 * @Block(
 *   id = "custom_text_block",
 *   admin_label = @Translation("Custom Text Block"),
 * )
 */
class CustomTextBlock extends BlockBase {

  /**
   * {@inheritdoc}
   */
  public function build() {
    $config = $this->getConfiguration();
    $text = $config['text'] ?? '';

    return [
      '#type' => 'markup',
      '#markup' => $text,
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function blockForm($form, FormStateInterface $form_state) {
    $form['text'] = [
      '#type' => 'textarea',
      '#title' => $this->t('Text'),
      '#default_value' => $this->configuration['text'],
    ];

    return $form;
  }

  /**
   * {@inheritdoc}
   */
  public function blockSubmit($form, FormStateInterface $form_state) {
    $this->configuration['text'] = $form_state->getValue('text');
  }
}

3. Module and Block Declaration:

• In my_module.info.yml:

name: My Module
type: module
description: Provides a custom text block.
core: 8.x

• In my_module.libraries.yml:

custom_text_block:
  version: 1.x
  css:
    theme:
      css/custom_text_block.css: {}

4. Clear Cache and Enable Module:

• Clear caches: drush cr
• Enable module: drush en my_module

5. Place Block:

• Go to Structure > Block Layout > Custom Block Library.
• Find "Custom Text Block" and place it in a region.
• Configure the text in the block settings.

Additional Notes:

• Customize the CSS in css/custom_text_block.css.
• Add more settings to the block form as needed.
• Consider using a text filter for formatting the text.
• Validate and sanitize user input in the block configuration form.