public void ReserveWatermarkSpace(PdfWriter writer)
{
if (_watermarkTemplate == null) return;
var canvas = writer.DirectContent;
canvas.SaveState();
canvas.SetGState(new PdfGState
{
FillOpacity = PageSetup.DiagonalWatermark.FillOpacity,
StrokeOpacity = PageSetup.DiagonalWatermark.StrokeOpacity
});
canvas.AddTemplate(_watermarkTemplate, 0, 0);
canvas.RestoreState();
}