Construct a new page from the given canvas instance.
A string pagename and the paperformat can be
defined. See below, for a list of known paper formats.
If rotated is set, the output is rotated by 90 degrees on the
page. If centered is set, the output is centered on the given
paperformat. If fittosize is set, the output is scaled to fill
the full page except for a given margin.
Normally, the bounding box of the canvas is calculated automatically
from the bounding box of its elements. Alternatively, you may
specify the bbox manually. In any case, the bounding box is
enlarged on all sides by bboxenlarge.