在线手册：中文英文

PDF_set_leading

(PHP 4, PECL pdflib >= 1.0.0)

PDF_set_leading — Set distance between text lines [deprecated]

This function is deprecated since PDFlib version 3, use PDF_set_value() with the parameter leading instead.

在线手册：中文英文

PHP手册 - N: Set distance between text lines [deprecated]

staemmler at gmx dot de (30-Nov-2000 05:22)

You need to call pdf_set_leading() before pdf_continue_text() every time for proper work.