PdfPattern Class
A pattern (ISO 32000-2, 8.7): a color that paints the areas it fills or strokes with a tile repeated over them (PdfTilingPattern) or a shading (PdfShadingPattern). It is set with PdfContentBuilder.SetFillPattern or PdfContentBuilder.SetStrokePattern.
public abstract class PdfPatternRemarks
The pattern space is the default coordinate space of the page, or of the form that uses the pattern, transformed by the matrix of the pattern.