PdfTilingBrush brush
= new PdfTilingBrush(new SizeF(page.Canvas.ClientSize.Width / 2, page.Canvas.ClientSize.Height / 3));
brush.Graphics.SetTransparency(0.3f);
brush.Graphics.Save();
brush.Graphics.TranslateTransform(brush.Size.Width / 2, brush.Size.Height / 2);
brush.Graphics.RotateTransform(-45);
brush.Graphics.DrawString("显示测试",
new PdfFont(PdfFontFamily.Symbol, 24), PdfBrushes.Violet, 0, 0,
new PdfStringFormat(PdfTextAlignment.Center),true);