Mobile - Fix line-height issue on Android

[geriux]

• Gutenberg Mobile PR: Fix line-height issue on Android  wordpress-mobile/gutenberg-mobile#4398

Fixes #37168

Description

This PR fixes an issue where the line-height value wouldn't be set after a font-size value was changed. Now it'll store the current line-height value and it'll be refreshed after any font size change.

Note: This feature is still under the __DEV__ flag only available running metro.

How has this been tested?

Precondition: Have a block-based theme activated.

• Open the WordPress Android app with metro running and setting the localGutenbergMobilePath path.
• Add a Heading block
• Type some text, with enough characters to fill in at least two lines
• Expect the line height to be shown correctly

Screenshots

Before	After

Types of changes

Bug fix

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[hypest]

👋 @geriux ! Antonis is AFK until a few more days so I thought of giving this a look from my side, hope that's OK.

I'm wondering, wdyt about perhaps using View.getLineSpacingExtra() or View.getLineSpacingMultiplier() (and View.getTextSize()) to work back from the setLineSpacing calculations to recover the current line height used, instead of maintaining a member variable for it? Not a big problem using a member variable, just wondering if we'd prefer to not have to maintain one (and need to make sure it is kept n sync in all the proper places)?

[geriux]

I thought of giving this a look from my side, hope that's OK.

Of course! Any feedback is more than welcome 🙇

When I started debugging this issue I tried getting the current values with those methods but I couldn't get the exact initial line-height value, I'll try those again to see what results I get 👍

[hypest]

When I started debugging this issue I tried getting the current values with those methods but I couldn't get the exact initial line-height value, I'll try those again to see what results I get 👍

Oh, I see. I didn't see a mention in the PR description so wasn't sure if you tried. FWIW, I haven't tried it myself so, your testing is already more complete apparently 😃

[antonis]

Thank you for wrangling this @geriux 🙇‍♂️
I tested the implementation on a Pixel 5 (Android 12) running metro and setting the localGutenbergMobilePath path with the head of WordPress-Android develop and everything works as expected. The code changes also look consistent to me 🎉

[geriux]

I'm wondering, wdyt about perhaps using View.getLineSpacingExtra() or View.getLineSpacingMultiplier() (and View.getTextSize()) to work back from the setLineSpacing calculations to recover the current line height used, instead of maintaining a member variable for it? Not a big problem using a member variable, just wondering if we'd prefer to not have to maintain one (and need to make sure it is kept n sync in all the proper places)?

While checking this I also remembered why I ended up with this approach, the line-height needs to be refreshed after a font size change has happened and only when there's a current line-height set. I tried to see if there's a way to get the react-native props that were set but I couldn't so I used the variable instead. I'll merge this change for now, thanks for the feedback and review! 🙇