var canvas = m_writer.DirectContent;
float fillTextSize = 6.0f;
string filltext = "this is the fill text!";
float filltextWidth = m_dejavuMonoBold.GetWidthPoint(filltext, fillTextSize);
PdfPatternPainter pattern = canvas.CreatePattern(px, py, filltextWidth, fillTextSize);
pattern.BeginText();
pattern.SetTextMatrix(0, 0);
pattern.SetTextRenderingMode(PdfContentByte.TEXT_RENDER_MODE_FILL);
pattern.SetRGBColorStroke(190, 190, 190);
pattern.SetRGBColorFill(190, 190, 190);
pattern.SetFontAndSize(m_dejavuMonoBold, 6.0f);
pattern.ShowText(filltext);
pattern.EndText();
canvas.Rectangle(px, py, pw, ph);
canvas.SetPatternFill(pattern);
canvas.Fill();

|this is the fill text! this is the fill text! this|
|his is the fill text! this is the fill text! this |
|is is the fill text! this is the fill text! this i|
|s is the fill text! this is the fill text! this is|
| is the fill text! this is the fill text! this is |

If I understand your question correctly, you need something like this: text_pattern.pdf

Text pattern example

We are using tiled patterns and the problem you experience is that all tiles are regular. If you want an irregular pattern, you need to use a workaround. Such a workaround is shown in the TextPattern example.

In iText 7 there is a Tiling class with a constructor for creating a tile. Declaring pattern you can set the width, height, X and Y offsets (like PdfPatternPainter in iText 5). Then you should create a PdfPatternCanvas using your tile:

PdfPattern.Tiling tilingPattern = new PdfPattern.Tiling(filltextWidth, 60, filltextWidth, 60);
PdfPatternCanvas patternCanvas = new PdfPatternCanvas(tilingPattern, pdf);
patternCanvas.beginText().setFontAndSize(font, 6.f);
// Start with an X offset of 0
float x = 0;
// Add 6 rows of text
// The font is 6, so use a leading of 10:
for (float y = 0; y 

As far as I know, adding the text more than once to the pattern, is the only way to achieve the type of pattern you require.

Click this link if you want to see how to answer this question in iText 5.