devicePixelRatio at 110% is incorrect
Categories
(Core :: Widget: Gtk, defect, P3)
Tracking
()
People
(Reporter: post, Unassigned)
Details
User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:77.0) Gecko/20100101 Firefox/77.0
Steps to reproduce:
Go to https://mozilla.github.io/pdf.js/web/viewer.html
Zoom to 110% (the browser, not the PDF).
Actual results:
The PDF rendering is not crisp. The console reports window.devicePixelRatio = 1.0909090909090908
Expected results:
window.devicePixelRatio = 1.10
In case this is reproducible, I added a custom zoom level at 125%, maybe this exposed a bug.
Comment 1•4 years ago
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Hi,
I was not able to reproduce this issue on Ubuntu 18.
Could you please try on our latest nightly build? You can download it from here: http://nightly.mozilla.org/. Also could you try with a NEW profile and in SAFE MODE (https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode) in case any configuration or addon is affecting.
And for the last could you try on Chrome to see if this behavior is consistent in another browsers.
Thanks.
I have the same on nightly and in a new profile. But the same happens in Chrome (except it has 1.100000023841858). The main problem is that I have visibly blurry PDFs when zooming the browser (not the embedded PDF viewer) to 110%, but this may be invisible on high pixel density screens.
I have a t430 running Debian. I just reported it in case someone can easily reproduce it. Otherwise I guess it is an obscure bug (I only noticed it because of the blurry PDFs of which I attached a screenshot), and it should perhaps be closed.
110%: https://postimg.cc/bGrV431L
100%: https://postimg.cc/w1f05LnN
EDIT: the previous example of blurriness of a PDF happens only at 110% where the device pixel ratio is also off from the expected value. At 133% for example it is crisp. For some reason Chrome is affected in the same way, so it may be a bug with the PDF viewer https://mozilla.github.io/pdf.js/web/viewer.html (in case it gets a zoom level from somewhere else and incorrectly combines it with the devicepixelratio).
Comment 4•4 years ago
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Bugbug thinks this bug should belong to this component, but please revert this change in case of error.
Updated•4 years ago
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Comment 5•1 years ago
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STR work for me. Testing on Windows might isolate it to pdf.js?
Updated•1 years ago
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Comment 6•1 years ago
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The value 1.0909090909090908
is equal to 12/11
and in pdf.js we approximate it in using Farey sequence with a limit of 8 hence it's approximated as 8/7
:
https://github.com/mozilla/pdf.js/blob/839be801a0d943d3426d4115f8f42b93de69e102/web/pdf_page_view.js#L921
If I set the limit to 11
here:
https://github.com/mozilla/pdf.js/blob/839be801a0d943d3426d4115f8f42b93de69e102/web/ui_utils.js#L265
the rendering is better.
Increasing the value will likely lead to increase the memory use.
Anyway there's likely a bug in pdf.js.
I don't know if this 12/11
for 11/10
is expected or not.
Comment 7•1 years ago
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As far as I can tell the Firefox builtin pdf viewer is not affected.
Description
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