The Return of the Embedded Font Issue

[TastyPi]

Prawn 2.5.0 appears to have reintroduced this old "Cannot extract the embedded font" issue prawnpdf/ttfunk#73

Using the exact same code to render a PDF using 2.4.0 does not have this issue.

[pointlessone]

Do you experience this issue if you disable font subsetting?

[TastyPi]

I tried with subset: true and subset: false, both have the issue

[pointlessone]

Could you please provide a minimal reproduction script and fonts you have issues with?

[pointlessone]

Also could you please list versions of the gems you use?

gem list --all --exact prawn ttfunk pdf-core

Or if you use bundler:

bundle list | grep -E 'prawn|ttfunk|pdf-core'

[TastyPi]

I tried a minimal example that just sets the font, but that did not reproduce the issue so it's definitely something deeper. Our PDF generation code is pretty complex, so it'll take me a while to create a minimal example, not sure when I'll find the time 😕.

Before downgrading (with issue):

bundle list | grep -E 'prawn|ttfunk|pdf-core'
  * pdf-core (0.10.0)
  * prawn (2.5.0)
  * ttfunk (1.8.0)

After downgrading (no issue):

bundle list | grep -E 'prawn|ttfunk|pdf-core'
  * pdf-core (0.9.0)
  * prawn (2.4.0)
  * ttfunk (1.7.0)

[TastyPi]

Thanks to the magic of Ruby, I've managed to log every call made to the Prawn::Document instance, and successfully reproduced the issue. I'm just cleaning it up to remove specific details and make it minimal.

[TastyPi]

Here we go, a minimal reproduction:

#!/usr/bin/env ruby

require "prawn"

pdf = Prawn::Document.new
pdf.font_families.update(
  "roboto" => {
    normal: "Roboto/Roboto-Regular.ttf",
    italic: "Roboto/Roboto-Italic.ttf",
    bold: "Roboto/Roboto-Bold.ttf",
    bold_italic: "Roboto/Roboto-BoldItalic.ttf",
  }
)
pdf.font("roboto")

pdf.text_box("€")

File.open("test.pdf", "w") do |file|
  pdf.render(file)
end

system "flatpak run com.adobe.Reader test.pdf"

I used Roboto here as an easy to acquire example, but it worked with another font I used. Seems to be an issue with the € symbol.

Even more curiously, this minimal example is also a problem with 2.4.0, though our full code is fine. So not sure what's going on there.

[TastyPi]

OK, it's a bug in ttfunk not prawn

The minimal example works with these versions:

gem "prawn", "2.4.0"
gem "ttfunk", "1.7.0"
gem "pdf-core", "0.9.0"

But breaks with these:

gem "prawn", "2.4.0"
gem "ttfunk", "1.8.0"
gem "pdf-core", "0.9.0"

i.e. the issue appears to be in ttfunk 1.8.0

prawn 2.5.0 requires ttfunk 1.8.0 so I haven't tested the prawn 2.5.0 ttfunk 1.7.0 combination to see if that works.

[pointlessone]

Thanks.

[coorasse]

Thanks for the deep dive @TastyPi, you helped us!
Will you open an issue on ttfunk, or is the team aware of it?
We locked ttfunk gem 'ttfunk', '< 1.8.0' in the meantime.

[TastyPi]

Filed prawnpdf/ttfunk#102, I wasn't sure if @pointlessone was going to do it as they appear to be the main ttfunk developer.

[pointlessone]

It's not immediately obvious where the issue is. PDF has rather complex relationships with fonts. Fonts are partially represented/duplicated in native PDF structures, some essential parts (according to fonts specs) of fonts are ignored in PDF, renderers don't exactly follow specs (both PDF and fonts). So the issue might not be in TTFunk even if it's related to fonts. Let's keep it as is, I'll figure it out when I'll have time to work on this.

[Salman464]

Encountered the same error recently Cannot extract the embedded font '3a9d5f+Recoleta-Bold'. Some characters may not display or print correctly.

Faced issue on the versions:

• pdf-core (0.10.0)
• prawn (2.5.0)
• ttfunk (1.8.0

Resolution:
Downgraded gems to resolve:

• pdf-core (0.9.0) (automatically downgraded with prawn and ttfunk)
• prawn (2.4.0)
• ttfunk (1.7.0)

I can confirm that downgrading to previous versions of prawn and ttfunk resolved the issue. not sure though if the issue is from ttfunk or prawn upgrade

[afdev82]

Do you experience this issue if you disable font subsetting?

I had the same error and I have "solved" it disabling the subsetting when registering the font family.
If I can inspect something to provide some help to solve the issue, let me know what I can do.
Thank you.

[timokleemann]

I can confirm that this Gem combination fixed the issue in my Rails 7 application:

gem "pdf-core", "0.9.0"
gem "prawn", "2.4.0"
gem "ttfunk", "1.7.0"

The special characters that were previously missing in Acrobat Reader are now visible again.