PDF character issue in Speedgrader when downloading Submission Comments

[cwar1]

We've come across a bug where g, %, and < characters do not render properly when you create a PDF from the “Download Submission Comments” option in Speedgrader for Mac users.

When you download the PDF and open in Adobe Acrobat Pro, the following error occurs: “Cannot extract the embedded font. Some characters may not display or print correctly”.  The PDF is, thus, unreadable. 

We found this error is caused by Speedgrader generating PDFs with a font (Lato) that isn't universally available on every system. Can we change the default font to something that is universally available, such as Arial? 

Instructors send these PDFs with comments to the students and other faculty members. This is a critical part of the assignment workflow and we have numerous Mac users on campus. 

[BrianLester]

I'm not sure if this is the source of the issue but @chriscas posted a list of supported fonts for the preview functionality in Speedgrader:

https://community.canvaslms.com/t5/Canvas-Question-Forum/Rendering-of-Attachments-in-Canvas/m-p/6129...

This might not be relevant to the download issue. 

[cwar1]

Unfortunately, this is a Speedgrader generated PFD so we can't control the font on our end. 

[BrianLester]

I understand, and my original answer may be irrelevent. Is this happening to every pdf or just to some?

I'm guessing the pdfs are generated base on user submissions which may use different fonts...

[cwar1]

Gotcha! This is happening for every PDF when using Mac. 

[BrianLester]

I just tested this- when I use Adobe Acrobat I get the same error message. When I use Preview on a mac there is no problem.

[chriscas · Accepted solution]

Hi @cwar1,

This was discussed on a slack channel a few months ago.  After a lot of discussion, some from The Ohio State did some investigation and found the bug is apparently in an underlying library Canvas uses to generate PDFs.  There is a GitHub issue discussion happening, but even a few months later it seems there has been no real fix from the creators of that library.  Without getting any more technical, it's basically a situation where Instructure has to wait for someone else to fix code before they can then implement the fix into Canvas.  I'd certainly like this to happen quickly, but since the issue was reported months ago and has not been fixed yet, I'm losing some optimism.

Hopefully this info helps.  Even though this isn't necessarily a fix, I'm going to mark it as the as the answer/solution, as it's the current reality of the situation.

-Chris

[sara_weaver]

It seems like waiting on some other person to fix a tiny bit of code is exposing a major flaw in the system here. I'm not an engineer, but surely there's another way around it? As mentioned to our CSM, this seems like one of those "quick, small wins" that Instructure has been touting. Not to mention it's an accessibility issue.