1377755 - Eyedropper shows wrong colors after scrolling

Status: NEW

(DevTools :: Inspector, enhancement, P3)

Description

[whisdol]

Attachment: eyedropper_after_scrolling_down.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0
Build ID: 20170630030203

Steps to reproduce:

1) Open a website that has more content than fits the page vertically, so a scrollbar is present. (e.g news.ycombinator.com)
2) From the Firefox menu, open Web Developer -> Eyedropper
3) While the eyedropper is open, scroll down on the page (with two fingers on a touchpad)


Actual results:

For a given position, the eyedropper shows the magnified area and color that were at this position on the screen before the page was scrolled.


Expected results:

The eyedropper should show the colors that are currently at the given position on the screen.

Comment 1

[Patrick Brosset <:pbro>]

When it starts, the eyedropper takes a screenshot of the viewport, in order to magnify the hovered area and sample pixel colors.
It does not take a screenshot again when you scroll though. Which is why scroll is actually disabled while the eyedropper is active.
You found a way to scroll however.
We should use this bug to either disable this way of scrolling, or fix the eyedropper so it takes a screenshot again on scroll.