tree 0e89c59c53ce46bc5f6c3fe7b32094e5eb4e0a9c
parent 11ec24d28e86b8809d7f17833b7306bb5c8401ec
author Emilio Cobos Álvarez <emilio@crisal.io> 1642419199 +0000
committer moz-wptsync-bot <wptsync@mozilla.com> 1642495472 +0000

Simplify combobox <select> code.

With this patch on its own we get some a11y tests failures, but those
are fixed on a later patch.

Combobox select no longer creates frames for its <options>, nor an
nsListControlFrame. Instead, it computes its right intrinsic size using
the largest size of the options. This is better, because we render the
option text using the select style so if the select and option styles
are mismatched it'd cause changes in the size of the select when text
changes. See the following in a build without the patch, for example:

  <select>
    <option>ABC</option>
    <option style="font-size: 1px">Something long</option>
  </select>

This seems like a rather obscure case, but it's important to get it
right, see bug 1741888.

With this patch we use the same setup in content and parent processes
(this needs bug 1596852 and bug 1744152). This means we can remove a
bunch of the native view and popup code in nsListControlFrame. A couple
browser_* tests are affected by this change and have been tweaked
appropriately (the changes there are trivial).

Not creating an nsListControlFrame for dropdown select means that we
need to move a bunch of the event handling code from nsListControlFrame
to a common place that nsComboboxControlFrame can also use. That place
is HTMLSelectEventListener, and I think the setup is much nicer than
having the code intertwined with nsListControlFrame. It should be
relatively straight-forward to review, mostly moving code from one part
to another.

Another thing that we need to do in HTMLSelectEventListener that we
didn't use to do is listening for DOM mutations on the dropdown. Before,
we were relying on changes like text mutations triggering a reflow of
the listcontrolframe, which also triggered a reflow of the
comboboxcontrolframe, which in turn updated the text of the anonymous
content. Now we need to trigger that reflow manually.

There are some further simplifications that can be done after this
lands (cleanup naming of openInParentProcess and so on, among others),
but I'd rather land this first (after the merge of course) and work on
them separately.

Differential Revision: https://phabricator.services.mozilla.com/D132719

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1744009
gecko-commit: 78130d73ca7565d795f350fa6e5eb3287f24eba6
gecko-reviewers: mconley, dholbert