1549626 - Fallback to basic colour contrast calculation algorithm when canvas one fails.

Status: RESOLVED FIXED

(DevTools :: Accessibility Tools, enhancement)

Description

[Yura Zenevich [:yzen] (please use "needinfo")]

We'd want to fallback on the original (most used) contrast calculation algorithm that tries to figure out the background colour of the element directly (or from its ancestry).

Comment 1

[Yura Zenevich [:yzen] (please use "needinfo")]

Attachment: Bug 1549626 - fix an issue with incorrect text colour blending. Fallback on basic colour contrast algorythm when canvas approach fails. r=mtigley

Comment 2

[Micah [:mtigley] (she/her)]

STR:

1. Go to https://www.reddit.com/r/aww/comments/bkicxb/subreddit_of_the_week_rcatbun/ (make sure you're logged in)
2. Inspect the "What are your thoughts?" placeholder text in the input field using the Accessibility picker tool.

ER:
A color and contrast score for the inspected text should be shown in the accessible highlighter info-bar and in the Accessibility Inspector side panel.

AR:
A message saying "Contrast: Unable to calculate" even though the inspected accessible is text.

Comment 3

[Yura Zenevich [:yzen] (please use "needinfo")]

Also for the opacity fix:

STR:

• go to about:welcome
• hover over the text under the email input field

ER: at the time of the this comment the values are https://contrast-ratio.com/#rgba%28255%2C%20255%2C%20255%2C%200.7%29-on-%23352f6d

AR: without the patch the values are higher because the opacity is dismissed.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3bf1f379d77e
fix an issue with incorrect text colour blending. Fallback on basic colour contrast algorythm when canvas approach fails. r=mtigley

Comment 5

[Oana Pop-Rus]

https://hg.mozilla.org/mozilla-central/rev/3bf1f379d77e