Plugin for creating PDFs with FPDF

web-assembler-fdfp-tutorial.php

<?php
/*
* Plugin Name: Web Assembler - FPDF Tutorial
* Description: A plugin created to demonstrate how to build a PDF document from WordPress posts.
* Version: 0.1
* Author: Web Assembler
* Author URI: https://www.webassembler.co.uk/
*/

/**
 * Note to developers- This is an untested, incomplete plugin that was written to accompany a blog post in 2018.
 * Do not use in production, test in a local environment first.
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

if ( ! class_exists('PDF_HTML') ) {
	return;
}

/**
 * 1. Create a folder for your plugin
 * 2. Inside this folder add this file as the main plugin file.
 * 3. Create a file called `webassembler-pdf-helper-functions.php` in the folder
 * 4. Download FPDF here: http://www.fpdf.org/ and store in the folder root
 * 5. In the plugin webassembler-pdf-helper-functions.php file, include the FDPF library at the top using instructions on FPDF website
 * 6. Copy all of the functions here: http://www.fpdf.org/en/script/script42.php and paste them in the same file
 * 7. Uncomment the line below to include the include
 */

// include( 'webassembler-pdf-helper-functions.php');
$pdf = new PDF_HTML();


if ( isset($_POST['generate_posts_pdf'])){
	webassembler_output_pdf();
}

add_action( 'admin_menu', 'webassembler_create_admin_menu' );
function webassembler_create_admin_menu() {
	$hook = add_submenu_page(
		'tools.php',
		'Web Assembler PDF Generator',
		'Web Assembler PDF Generator',
		'manage_options',
		'wa-fdpf-tutorial',
		'webassembler_fpdf_create_admin_page'
	);
}

function webassembler_output_pdf() {
	$posts = get_posts( 'posts_per_page=5' );

	if ( ! empty( $posts ) ) {
		global $pdf;
		$title_line_height   = 10;
		$content_line_height = 8;

		$pdf->AddPage();
		$pdf->SetFont( 'Arial', '', 42 );
		$pdf->Write(20, 'Web Assembler FPDF Tutorial');

		foreach ( $posts as $post ) {

			$pdf->AddPage();
			$pdf->SetFont( 'Arial', '', 22 );
			$pdf->Write($title_line_height, $post->post_title);

			// Add a line break
			$pdf->Ln(15);

			// Image
			$page_width      = $pdf->GetPageWidth() - 20;
			$max_image_width = $page_width;

			$image = get_the_post_thumbnail_url( $post->ID );
			if ( ! empty( $image ) ) {
				$pdf->Image( $image, null, null, 100 );
			}
			
			// Post Content
			$pdf->Ln(10);
			$pdf->SetFont( 'Arial', '', 12 );
			$pdf->WriteHTML( $post->post_content );
		}
	}

	$pdf->Output( 'D','webassembler_fpdf_tutorial.pdf' );
	exit;
}


function webassembler_fpdf_create_admin_page() {
?>
<div class="wrap">
	<h1>Web Assembler - Wordpress PDF Generator</h1>
	<p>Click below to generate a pdf from the content inside all the Wordpress Posts. </p>
	<p>Each post will be on its own pdf page containing the post title and post content.</p>
	<form method="post" id="webassembler-fdpf-form">
		<button class="button button-primary" type="submit" name="generate_posts_pdf" value="generate">Generate PDF from Wordpress Posts</button>
	</form>
</div>
<?php
}