Sets a coloured tiling pattern or a shading pattern as the fill colour (/Pattern cs /name scn).
public void SetFillPattern(PdfPattern pattern)
A valid pattern of this document: a shading pattern, or a coloured tiling pattern.
ISO 32000-2 §8.7.3.2 and §8.7.4.2: the Pattern colour space is selected with cs when it is not the current one, and the
pattern, named in the Pattern resources, with scn. The pattern's matrix maps pattern space to the default space of
the page or form this canvas draws on (§8.7.2), whatever the current transformation. Records PDF 1.2, and 1.3 for a shading pattern.