pdfSetPrintDPI
Set the print resolution.
void pdfSetPrintDPI(PDFViewerHandle viewer, int hDPI, int vDPI)
This function sets the horizontal and vertical print resolution,
in dots per inch (DPI).
The horizontal and vertical resolutions are typically the same. (There are exceptions, such as some chart printers.)
C:
pdfSetPrintDPI(pdf, 300, 300);