How to do this? There are several approaches, but you must be willing to do your own research. You can paint PDFs in a variety of ways:
- using graphics primitives in PHP libraries such as FPDF and TCPDF
- using reporting software with document templates, such as JasperReports (requires server root access)
- by converting from HTML, say via
wkhtmltopdf
(free) or Prince (expensive)
- by manipulating SVG and rendering it to PDF, say in Inkscape (I've not seen other people taking this approach, but I have a working demo - see here. Only recommended if you are comfortable manipulating XML programmatically)
Remember that to get hi-res output (300-600pdi) on paper, you need to use proper fonts or vector graphics. These render at the resolution required, and won't pixellate if you use them properly. Failing this, use bitmaps at the correct resolution, so if you have a 1200px square image, and you wish to print at 600pdi, then the image cannot be larger than 2 inches either side.
In general it is best not to rely on third-party conversion services unless you have a contract with them - since they can take their site down or deny access at any time, and your work would be wasted.