Open Bug 1541341 Opened 6 years ago Updated 2 years ago

Fullpage screenshots on some internal about: pages do not capture out of view content

Categories

(DevTools :: General, defect, P3)

defect

Tracking

(Not tracked)

UNCONFIRMED

People

(Reporter: Fanolian+BMO, Unassigned)

References

(Blocks 1 open bug)

Details

(Keywords: reproducible)

Attachments

(1 file)

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User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Firefox/68.0
Build ID: 20190402214908

What were you doing?

  1. Go to about:preferences or about:addons. Find a page with content long enough to go out of view.
  2. Open Devtools.
  3. Take a screenshot including out of view content by either:
    3a. using the screenshot button on toolbar.
    3b. :screenshot in Console.
    3c. highlighting a really long node in Inspector, right click and select Screenshot Node.

What happened?

The screenshots saved, or copied to clipboard, contain only the content currently in view.
Attached is a sample taken on about:preferences.

What should have happened?

A long screenshot with all content should be saved.

Anything else we should know?

I did not test all about: pages. about:preferences and about:addons are the defective ones. Some working pages includes about:profiles, about:support, and new about:config.

Firefox screenshot is either disabled (greyed-out) or page action buttons are not available on these pages. I cannot compare the result with both functions.

Has Regression Range: --- → no
Has STR: --- → yes
Keywords: reproducible
Summary: Fullscreen screenshots on some internal about: pages do not capture out of view content → Fullpage screenshots on some internal about: pages do not capture out of view content

I can reproduce this, taking a screenshot of about:preferences from the console in windows produces just a viewport screenshot, it doesn't make a difference to specify the --fullpage parameter or not (i.e. :screenshot --fullpage produces the same output as only using :screenshot).

I believe Firefox Screenshots might be disabled by design for these pages, but don't take my word for it--all I can say is that I can confirm that the DevTools side is not quite working as expected :-)

Blocks: 1483143
Priority: -- → P3

So this might be because of the design of the pages. We use window object to take screenshot of the whole page, however large it is, captured in the screenshot. But some of the pages like bugzilla, about:preferences, they have child elements which in turn provide illusion of full page scroll, instead the child is like flex and take up the viewport with overflow:auto.

Don't know what to do in that type of situations. I think we are doing a good job at generic things.

Looks like this will be fixed with my patch for Bug 1678483

Depends on: 1678483

(In reply to Nicolas Chevobbe [:nchevobbe] from comment #3)

Looks like this will be fixed with my patch for Bug 1678483

Bug 1678483 and bug 1474006 do not fix this bug. I still cannot capture out-of-view content.
In addition it now breaks the Screenshot Node for internal pages. Using it, even on a small node, hangs the browser completely.

Ah sorry, I misunderstood the issue.
So yes, taking a fullpage screenshot will only remove the top-level overflow. On about:preferences for example the elements that overflows, .main-content is a children of an hbox that does not overflow (and you can see that the left sidebar does not overflow and stays "fixed" when scrolling)
We can really resolve this issue, as we would have to expand all overflown element in the page, which can be tricky, and will probably return false positive.

I can reproduce the issue for screenshot node, I'll file a bug for that

I filed Bug 1691349 for the browser hang

Severity: normal → S3
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