Unable to integrate custom fonts and bold text when inserting text into PDFs using PyMuPDF

[jahnvi-sikligar-tcgls]

I’m implementing a PDF personalization pipeline that uses page.insert_textbox() to add personalized text to existing PDFs. While the text insertion works, custom fonts and bold styling consistently fail, even when trying different font registration and fallback strategies.

PyMuPDF either:

• silently ignores the requested custom font and falls back to Helvetica,

• or raises an error if a non-built-in font name is passed.

The same issue occurs with bold text: setting the bold flag or using font names such as "helv-bold" or custom font files does not change the rendered output.

What I Expected

• The ability to specify a custom .ttf font and use it during insertion.
• Bold text (bold=True) or bold variants of built-in fonts to render correctly.
• insert_textbox() to honor the requested font metadata.

What Actually Happens

• Custom fonts are ignored or cause insert_textbox to fail.
• Bold text never renders bold, regardless of flags or font naming conventions.
• Only core fonts (helv, times, courier) work, and only in non-bold styles.

Code Sample

status = page.insert_textbox( rect, text, fontsize=fs, fontname=fontname, # custom fonts or bold variants fail align=0, color=text_color )

Do let me know if any more details are needed.

[JorjMcKie]

This is not an issue but a Discussions item: transferring ...

[jahnvi-sikligar-tcgls]

Thanks for the help. But is there a way to add custom fonts and bold certain texts while working in PDF?

[JorjMcKie]

Using your own font requires specifying the name of the file or the its content in memory (font buffer). This must happen per page - not per PDF.

Second you must specify the fontname parameter. This string must be different from all font names defines for the Base-14 fonts (like "helv", "tiro", "Helvetica" etc.) and also be unique among all the font names in use by the page.

Best use this approach:

font = pymupdf.Font(fontfile="path to font")
fontname = "mycoolfont"  # this is NOT the font filename!

# once per page:
page.insert_font(fontname=fontname, fontbuffer=font.buffer)

# insert text with the font:
page.insert_textbox(..., fontname=fontname)

Notes:

• Bold, italic, ... etc. variants of a font are implemented in different files!
• You cannot mix multiple fonts (respectively variants) in the same insert_textbox.
• More comfortable support for text insertion (and more) is offered by page.insert_htmlbox.

[jahnvi-sikligar-tcgls]

Is it possible to maintain the PDF's layout and content if we use page.insert_htmlbox()?

[JorjMcKie]

Here is my post in StackOverflow, which you seem to have submitted in addition.

[JorjMcKie]

Is it possible to maintain the PDF's layout and content if we use page.insert_htmlbox()?

What does that mean?

[JorjMcKie]

Method insert_htmlbox() works much like insert_textbox() in that it position the text across the rectangle in the best possible way.
In addition however it understand HTML syntax and reacts to tags like <b> to start bold text. It also detects whether text portions require other than the declared font(s) and automatically install the needed additional font.
You can influence this automatism by specifying HTML stylesheet instructions that can contain font information based on @font-face.
The method can output tables given in HTML syntax plus images if the text references them.