Edit screen: add emoji compat

[mzorz]

This PR implements EmojiCompat so to be able to have emojis on devices that may not have support for them on their installed Fonts.

I explored an alternative PR in #55, but I think this one is a mergeable candidate given it uses the latest EmojiCompat library which is supposed to encapsulate the problems #55 tackles separately (downloading the fonts, then using them).
Let's keep #55 as an exploration, can probably close it as well if this one proves to be working fine.

Resources:

• Official training (a bit outdated, things are not exactly as explained there as support library v28.0.0 has moved to jetpack androidx package now, but the core mechanism still is the same) https://developer.android.com/guide/topics/ui/look-and-feel/emoji-compat#using-widgets-with-appcompat
• Video https://www.youtube.com/watch?v=sYGKUtM2ga8
• demo sample app https://github.com/googlesamples/android-EmojiCompat

Didn't know which the needed replacement for the 28.0.0 support library was, but using jetpack it was enough to declare EmojiCompat in MainActivity and then let the IDE add the correct dependencies.

Basically followed the sample app https://github.com/googlesamples/android-EmojiCompat and implemented the core parts here.

Notes:

• the certificates used for FontRequest are borrowed from Google's EmojiCompat sample app, I haven't found anywhere in the docs that these should (or should not) be the ones to be used, but judging from the package names it looks like these certs should correspond to Google's, as this is how the call looks like:

Note on this: these are indeed the same ones that Android Studio adds to your project when following the steps described in #55, so these are 👍

• the requested Font is as per the sample app Noto Color Emoji Compat, the information on which can be found here: https://www.google.com/get/noto/help/emoji/

ToDo:

• move the initEmojiCompat() method from MainActivity to the Application instance when Intro: Use SharedPreferences to track when to show intro flow #47 gets merged done in d8ddc62

[mzorz]

Note: while using EmojiCompat is the "right" (official) way to go (that is, just download the Font and use it), this is an interesting approach to checking availability as well

[aforcier]

@mzorz I tested this one and #55 and I have a bunch of questions 😀

IIRC we discussed these PRs and you mentioned that they're not adding support for missing emojis (since we're still reliant on row_emoji.xml, and we're tracking this improvement in #110). But I'm not sure what the testing steps are.

Testing develop and these two PRs on my Pixel 3, I notice a few emoji that were B&W before are using Google fonts when running #55:

However, when running this branch nothing seems changed.

I was also curious what would happen on a device with no Google APIs so I tried on an emulator. Neither branch shows the modified emoji - I guess this is expected. Something we may need to consider for markets without Google Play.

[mzorz]

Testing develop and these two PRs on my Pixel 3, I notice a few emoji that were B&W before are using Google fonts when running #55:

Oh that's an interesting observation, I think I didn't notice that before

But I'm not sure what the testing steps are.

You're totally right I forgot to add steps to test here. I tested by adding breakpoints in the callbacks to make sure the font downloader callbacks were being called, and the .process() call was being made to run spans through it on the desired TextViews, but we need to make sure one or both approaches are working correctly before merging.

Currently looking into this, will loop back 👍

[peril-automattic]

You can test the changes on this Pull Request by downloading the APK here.

[mzorz]

Tried by using this in the EmojiCompat configuration:

        config.setReplaceAll(true)
        config.setEmojiSpanIndicatorEnabled(true)

The second line paints the background for the EmojiSpan in green. This shows the emoji that didn't have color are not recognized as emoji, and so these are not replaced with an EmojiSpan by the EmojiProcessor (https://developer.android.com/reference/android/support/text/emoji/EmojiSpan) and thus don't have the green background.

Why aren't these recognized as Emoji? Let's see.

Looking further down into EmojiCompat's sourcecode realized this is because it will only replace one-byte unicode values as emoji if setUseEmojiAsDefaultStyle() is true (look in this line in EmojiProcessor, then isInFlushableState makes this check here ).

Made this change in commit fe49ad2 and now it works as expected 👍

So, this is how it looks now:

I think we can merge this PR if it looks good to you @aforcier , and close #55 (which helped me a lot in understanding how all of this works but this current PR is preferred given it's the recommended way to handle things today). Let me know!

[aforcier]

Confirming that it's working correctly now 👍 your explanation makes sense, let's merge this and close #55, we can revisit it later if it comes up for some reason.