843927 - Built-in PDF viewer doesn't position glyphs correctly

Status: RESOLVED WORKSFORME

(Firefox :: PDF Viewer, defect, P3)

Description

[fred]

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:19.0) Gecko/20100101 Firefox/19.0
Build ID: 20130215130331

Steps to reproduce:

Using the released Firefox 19.0, I brought up a good-sized PDF from fcc.gov.  


Actual results:

It was fast and it all rendered.  But the text rendering didn't look *quite* right.  So I did a screen shot and blew up a snippet of the rendered text.  I also opened the same PDF in Adobe Reader and blew up the exact same snippet.  At 800% scale, it is obvious.  Some glyphs are to the left or right of where they belong.  In Adobe Reader, spacing is very precise and smooth.  In pdf.js, as an example, the "i" and "l" are rendered too far to the left, while "a" is too far to the right.  So "digital" looks like "di gi tal". "th" and "an" practically become ligatures.


Expected results:

It should read the TrueType font metrics more accurately and position the glyphs correctly.

Comment 1

[Loic]

Provide PDF URL or attach the PDF to this bug, please.

Comment 2

[fred]

The PDF I was testing was this one:
http://transition.fcc.gov/Daily_Releases/Daily_Business/2013/db0220/FCC-13-22A1.pdf

I blew up paragraph 14 at the top of page 6.  With "automatic zoom" at 100%, look at the word "digital" in the last line above the picture.  Blow up a screen shot for a closer look.

When you let pdf.js expand it to a larger size, it looks better; the glyph placement, at least relative to glyph size, is more accurate. 

I put my screen shots up here, the second slide being a huge blowup of the shots on the first:
http://www.ionary.com/pdfjs-test.pptx

Comment 3

[mozilla.pva]

I have found a much more glaring example of a PDF with improperly positioned glyphs: http://www.unicode.org/charts/PDF/U2700.pdf

Page 1 evince:  http://bayimg.com/DaJDgaaeo
Page 1 firefox: http://bayimg.com/DAJdDAAEO
Page 2 evince:  http://bayimg.com/dajdfAaeO
Page 2 firefox  http://bayimg.com/DAjDeAAeO

This is with firefox 19.0 on ubuntu.

Comment 4

[Mack Duan]

@PST: Your issue does not seem related. Could you open another bug for it?

Comment 5

[Petruta Horea [:phorea]]

Mozilla/5.0 (Windows NT 5.1; rv:29.0) Gecko/20100101 Firefox/29.0
Some text glyphs are still visible on latest Nightly (20140114030236), marking as NEW.

Comment 6

[Brendan Dahl [:bdahl]]

Attachment: fcc.png

I can no longer reproduce. See the attached screen shot comparing acrobat and pdf.js. This is with Firefox 58 on Windows 10.