905687 - Make nsComboboxDisplayFrame use their font height as their intrinsic height instead of the tallest option

Status: RESOLVED WONTFIX

(Core :: Layout: Form Controls, defect)

Description

[Mounir Lamouri (:mounir)]

Attachment: Patch

This would allow pages that want to show different font for the <select> and the <option> and will fix the bug that the patch in bug 674443 produces.

Comment 1

[Mounir Lamouri (:mounir)]

Passes try: https://tbpl.mozilla.org/?tree=Try&rev=e54073bfcdc7

Comment 2

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

How this would deal with options that are different sizes?

Consider, for example:

<select>
  <option>One</option>
  <option>Two</option>
  <option style="font-size: 30px">Three</option>
</select>

There are more subtle cases of the same thing when the options
contain mixes of languages that require different fonts to render.
For example, a mix of Chinese and English at 16px can, depending on
vertical alignment, be taller than either alone, because you have to
add the larger ascent above the baseline (Chinese) to the larger
descent below the baseline (English).

Comment 3

[Mounir Lamouri (:mounir)]

I don't know for different languages but the idea of that patch is that we would not worry about the <option>'s font-size. The <option> list will be shown using the specified font-size but the <select>'s height will be based on its actual font-size (and font then).

Basically, if you do:
<select style="font-size: 12px;">
  <option style="font-size: 2px;">foo</option>
  <option style="font-size: 22px;">foo</option>
  <option style="font-size: 42px;">foo</option>
</select>

It will show a select that will use a 12px font-size even if the option list will be showing various different font-size.

Does that make sense?

Comment 4

[Ting-Yu Lin [:TYLin] (PST, UTC-7)]

We already implemented this idea, and Bug 1716212 fixed <select>'s auto height if its displayed <option> contains a mixes languages (the subtle case in comment 2).