[Android] Add support for subcomposition and sharing state

[jonnyandrew]

Changes

• Add support for subcomposition. By adding a new a mode that doesn't register any state updates, the editor can be composed purely for measurement purposes and not trigger a state update.
• Add support for sharing state between editors at different call-sites; allow the editor to be constructed at a new call site without side effects. The AndroidView factory and update blocks can be called again by the replacement editor instance safely.
• Preserve trailing new lines on restoring state by saving and restoring the internal HTML representation of the editor rather than the message HTML.
• Make the state observable so that, when an editor leaves the composition, it doesn't need to clean up its reference from the state and cause unwanted state updates.
• Fix some issues with unstable classes in the state.
• Update some compose dependencies including compose compiler.

Context

To enable the editor to be embedded in complex layouts that require pre-measurement and/or multiple layout trees.

• Part of [Story] RTE full screen mode in EX element-hq/element-meta#1973

[julioromano]

Just a few nits hoping they area useful. Sorry for not being more of help here.

Although I don't understand what's the reason for switching off registerStateUpdates in a subcomposition. Without state updates the RTE is pretty much useless isn't it?

[jonnyandrew]

Although I don't understand what's the reason for switching off registerStateUpdates in a subcomposition. Without state updates the RTE is pretty much useless isn't it?

In a subcomposition the editor is composed twice, once for measurement and once again to be placed in the layout given the first measurement. During the first measurement I need the editor to just be a dumb view and read the state but not try to update it in any way that might impact the second step. Hope that makes sense?

An alternative could be to create a new instance of the state for every subcomposition but we'd also have the issue of the first composition requesting focus each frame, which I'm not sure how to avoid.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (7fa6e63) 87.06% compared to head (36e44f7) 89.88%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #822      +/-   ##
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+ Coverage     87.06%   89.88%   +2.82%     
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  Files           155       82      -73     
  Lines         17983    14725    -3258     
  Branches        901        0     -901     
============================================
- Hits          15656    13236    -2420     
+ Misses         2068     1489     -579     
+ Partials        259        0     -259     

Flag	Coverage Δ
uitests	?
uitests-android	?
unittests	89.88% <ø> (+3.36%)	⬆️
unittests-android	?
unittests-ios	?
unittests-rust	89.88% <ø> (ø)

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see 73 files with indirect coverage changes

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[julioromano]

Although I don't understand what's the reason for switching off registerStateUpdates in a subcomposition. Without state updates the RTE is pretty much useless isn't it?

In a subcomposition the editor is composed twice, once for measurement and once again to be placed in the layout given the first measurement. During the first measurement I need the editor to just be a dumb view and read the state but not try to update it in any way that might impact the second step. Hope that makes sense?

An alternative could be to create a new instance of the state for every subcomposition but we'd also have the issue of the first composition requesting focus each frame, which I'm not sure how to avoid.

I still did not understand this completely. Can you point me to a piece of code that shows this? (using the RTE in a subcomp).

[jonnyandrew]

Sure, my draft work for full screen mode in Element X shows this in action: vector-im/element-x-android/jonny/rte-full-screen