Pdf Generation

By the end of this lesson you'll turn HTML and CSS into a polished invoice PDF, stamp every page with a header, footer and page number, drop in a logo, and choose between streaming a download or saving the file — the exact skills behind every "Download as PDF" button you've ever clicked.

Part of the free Php course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

What You'll Learn in This Lesson

1️⃣ Choosing a PDF Library

PHP has no built-in PDF maker, so you add one with Composer (PHP's package manager). The three families you'll meet: Dompdf and mPDF turn an HTML + CSS template into a PDF — ideal when you can describe the document as a web page. TCPDF and the classic FPDF are programmatic : you place each piece of text, box and image at exact coordinates. mPDF is the pick when you need strong Unicode or right-to-left scripts like Arabic. Start from how you want to describe the page, and the choice falls out.

2️⃣ HTML → PDF: an Invoice with Dompdf

This is the most common real-world path. You build the invoice as a normal HTML string with a <style> block, then Dompdf renders it to PDF bytes. Two things to notice: the CSS lives inside the HTML (Dompdf won't fetch a separate .css file), and output() hands you the raw bytes so you decide whether to save, stream, or email them.

The PDF will look almost exactly like the HTML would in a browser — same green header, same table — which is why Dompdf is so productive. The catch is that it understands only a subset of CSS (no flexbox, no grid); you'll see how to dodge that in Common Errors.

3️⃣ Headers, Footers, Page Numbers & Images

Multi-page documents need the same logo and page numbers on every page. With TCPDF you get this almost for free: override the Header() and Footer() methods and TCPDF calls them automatically on each new page. Image() drops a logo at exact coordinates, and getAliasNumPage() / getAliasNbPages() fill in "Page X of Y" — TCPDF substitutes the real totals after the whole document is built.

4️⃣ Streaming vs Saving

Once the PDF exists you must say where it goes . Stream it and the bytes flow to the browser — either viewed inline in the tab or popped as a download dialog. Save it and the bytes land in a file you can store, attach to an email, or serve later. The destination is just a flag — Dompdf's stream() vs output() , or TCPDF's Output(name, "I"|"D"|"F"|"S") — but there's one golden rule beside it.

The golden rule: when you stream, the PDF bytes must be the first thing the server sends. A stray echo , a blank line, or even a space before <?php sneaks ahead of the PDF and corrupts it — the browser downloads a file that won't open. If you don't need to stream, use output() / Output("", "S") to grab the bytes safely.

5️⃣ Your Turn: Finish the Dompdf Script

Now you try. The script below is wired up except for the three method calls that actually do the work. Fill in each ___ using the 👉 hint, then run it in a project where you've installed Dompdf and check it against the Output panel.

One more — this time a TCPDF footer that needs to show "Page X of Y" . Fill in the two helpers that return the current page and the total.

Common Errors (and the fix)

• Your layout collapses — flexbox / grid is ignored — Dompdf is not a browser and supports only a subset of CSS. display: flex and grid simply do nothing. Lay PDFs out with tables and fixed widths, and put CSS in a <style> block or inline — external .css files aren't fetched by default.
• "Allowed memory size of … bytes exhausted" — a big table or a high-resolution image blew past PHP's memory_limit while rendering. Raise it for the script with ini_set('memory_limit', '256M') , shrink images before embedding them, and split huge reports across pages instead of one giant page.
• £, €, accents or emoji show as empty boxes — the active font has no glyph for those characters. Use a font with wide coverage ( DejaVu Sans ships with both Dompdf and TCPDF) and make sure your HTML is UTF-8. For Arabic or Hebrew, switch to mPDF .
• The downloaded PDF won't open / "file is damaged" — something was printed before the PDF bytes. When streaming, the PDF must be the first output, so remove any stray echo , blank line, or space before <?php (and drop the closing ?> tag). Or save with output() instead of streaming.

Pro Tips

• 💡 Generate slow PDFs in the background. A 10-page report can take several seconds — queue it as a background job and email the user a download link instead of blocking the request.
• 💡 Design the template in a browser first. Build and tweak the HTML in Chrome, then hand it to Dompdf — but keep to tables and simple CSS so it survives the conversion.
• 💡 Set a Unicode default font once. DejaVu Sans covers Latin, currency symbols and accents, so you avoid the empty-box surprise on a customer's name.

📋 Quick Reference — PHP PDF Generation

Task

Code

Notes

Install Dompdf

composer require dompdf/dompdf

HTML + CSS → PDF

Install TCPDF

composer require tecnickcom/tcpdf

Coordinate-based

Render HTML

$d->loadHtml($h); $d->render();

Dompdf

Save bytes

file_put_contents($f, $d->output());

to a file

Download

$d->stream("x.pdf");

browser download

TCPDF page

$p->AddPage(); $p->Cell(...);

add page + text

Page numbers

getAliasNumPage() / getAliasNbPages()

in Footer()

TCPDF dest

$p->Output($n, "I"|"D"|"F"|"S");

view/down/file/string

Frequently Asked Questions

Mini-Challenge: A Receipt PDF

No code is filled in this time — just a brief and an outline. Write it yourself in a project with Dompdf installed, run it, then check your result against the expected output in the comments. This is exactly the build-render-save loop you'll use on every real document.

🎉 Lesson Complete!

• ✅ PHP makes PDFs through Composer libraries — there's no built-in maker
• ✅ Dompdf / mPDF convert HTML + CSS; TCPDF / FPDF place elements by coordinate
• ✅ Build invoices from an HTML template, keeping CSS inline or in a <style> block
• ✅ Override Header() / Footer() for logos and "Page X of Y" on every page
• ✅ Stream bytes to the browser or save them — but stream nothing before the PDF
• ✅ Watch the gotchas: limited CSS, memory on big PDFs, and Unicode fonts
• ✅ Next lesson: Localization — build multilingual PHP apps with translations and locale-aware formatting

Practice quiz

Continue this course

• Previous: Image Processing
• Next: Localization