When does showText() function change lines during glyphs plotting?

[hard-quale]

Hello everyone. I have only one question about interpretation of the code. Perhaps it is silly but I am stuck for a while at this point and I decided to call for help. I am adapting the pdf.js code the render only part of the pdf that I want. So I managed to change a bit the functions "appendText" and "showText" inside PDF.js. Now, while I am trying to interpret the showText algorithm, I am trying to understand how can I identify when it jump one line to another when it loops over the glyphs. Who knows the algorithms and the subject will understand me. The algoritm loops over the glyphs to plot them on the canvas on the screen, character per character, and somehow it changes lines and keeps plotting the next line. I coudn´t identify how the algorithm represents this line switching. It has "y-axis" represenation but neither "current.y" or "current.textMatrix[5]" variables worked for me. Does anyone out there know what I am talking about?

Thank you for your attention,

best regards,

Joao V. Dornas

Attach (recommended) or Link to PDF file here:

Configuration:

• Web browser and its version:
• Microsoft Edge version 116.0.19
• Operating system and its version:
• Microsoft Windows version 11
• PDF.js version:
• pdfjs-3.1.81-dist
• Is a browser extension:
  No, it is not.

Steps to reproduce the problem:

1. It is not a problem. I have a question about the code.

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):