printHDPI

Set the horizontal print resolution.
[read/write property] printHDPI([out, retval] int *dpi) printHDPI([in] int dpi)
This property sets the horizontal print resolution, in dots per inch (DPI).

The horizontal and vertical resolutions (see printVDPI) are typically the same. (There are exceptions, such as some chart printers.)

VB6:
viewer.printHDPI = 300 viewer.printVDPI = 300
printVDPI