There are a lot of procedural tools for generating HTML, lots, if modern browsers fully supported print CSS then you could use them for complex PDF generation, or direct printing, either client side or on the server headless.

If your app is a web app this is a no brainer, the users browser could simply do the print or PDF conversion as needed.

I do see a use for more direct libraries in native apps, although if every native client had a browser control with full print CSS support even then it might not be such an issue.