Generating PDFs with Playwright's Ruby Client
If you need to turn web pages into PDFs with the playwright-ruby-client pdf library, this guide shows you the exact steps and caveats. The Ruby client extends Playwright's core API, letting you script PDF creation directly from Ruby code without external tools. Learn how to capture precise PDF screenshots, avoid common quality loss, and run everything headlessly, plus where to find the best documentation and community examples.
What the Ruby Client Adds to Playwright
The Ruby client wraps Playwright's Chromium, Firefox, and WebKit engines, exposing methods like page.pdf that mirror the JavaScript API. It adds Ruby‑friendly syntax, automatic type conversion, and built‑in waiting mechanisms, so you can call pdf generation after navigation without manual sleep calls. Under the hood it translates Ruby blocks into async Playwright commands, preserving the full feature set while feeling native to Ruby developers.
How to Capture PDF Screenshots in Ruby
Calling page.pdf with a hash of options produces a byte stream you can write to disk. For example, page.pdf(path: 'report.pdf', format: 'A4', print_background: true) captures the full viewport, including CSS backgrounds, at 96 dpi. To snapshot a specific element, combine page.locator('#invoice').screenshot(path: 'section.png') then embed that PNG into a PDF with the Prawn gem, yielding precise visual fidelity for dynamic sections.
Why Do PDFs Lose Quality When Generated?
PDFs often appear blurry because Playwright defaults to screen‑density rendering, which matches the monitor's devicePixelRatio rather than print resolution. Supplying scale: 2 in the pdf options forces vector‑level scaling, producing sharper text and line art. Additionally, disabling CSS image smoothing (image-rendering: pixelated) before generation prevents browsers from downsampling raster images, a hidden cause of quality loss in charts and logos.
Can the Client Render PDFs in Headless Mode?
Headless mode runs Chromium without a visible UI, yet the pdf method still works because the rendering pipeline remains fully functional. Internally Playwright launches a headless browser instance, renders the DOM, then streams the layout tree to the PDF generator. The only limitation is that fonts loaded via @font-face may need explicit preloading, as headless sessions skip lazy network requests that a visible browser would trigger.
Where to Find Playwright Ruby PDF Resources
The official Playwright Ruby repo on GitHub contains a pdf_examples directory with ready‑made scripts. The RubyDoc site lists page.pdf signatures and supported options. Community gems like playwright-ruby-client-pdf‑helper extend the base client with shortcuts for margins and headers. Finally, the Playwright Discord channel's #ruby‑client thread regularly shares snippets for complex invoice and report generation workflows.
Frequently Asked Questions
how do I set custom margins for a PDF in Playwright Ruby?
Pass a margins hash to page.pdf, e.g., margins: {top: '1cm', bottom: '1cm', left: '2cm', right: '2cm'}. This overrides the default 0.4 inches and ensures consistent whitespace across printed pages.
can I generate a PDF without launching a full browser instance?
No, Playwright always starts a Chromium, Firefox, or WebKit process to render the page before PDF creation. The browser runs headlessly, but the rendering engine is required to compute layout and styles.
is the PDF output vector or raster when using Playwright Ruby?
Text and vector graphics are output as true vectors, while images remain raster. Supplying a higher scale factor improves raster image resolution, but the core PDF remains a mix of vector and raster content.