[mfazekas]

rive-android keeps FontFallbackStrategy.stylePicker only in a WeakReference (still the case in 11.12.1), and HybridRiveFontConfig.applyFallbackFonts() passed it an anonymous object nothing else held. A GC shortly after setFallbackFonts() collected the picker, so text needing a fallback (Thai, Hebrew, Arabic, CJK) rendered blank with FindFontFallback - no fallback found. This keeps a strong reference until clearFallbackFonts(). Affects both Android runtimes, since the file is shared.

Root cause and fix by @edgartoomikw in #369, thanks!

Adds an Issue369FontPickerGC reproducer page: it sets Kanit as the fallback, loads the font another 250 times to make the Java heap collect, then mounts a view showing Thai text. On the Pixel 6 emulator with rive-android 11.12.1, the text is blank without the fix and renders in Kanit with it.

Fixes #369

[Copilot]

🟡 Changes recommended

Overlapping font updates can leave the installed picker unretained, and stale reproducer runs can overwrite Reset or restart state because cancellation and font setup are not safely coordinated.

2 open issues

• Synchronize fallback font picker publication and retention · New
• Cancel and serialize superseded font setup runs · New

What changed in this PR

This PR addresses #369 by retaining the Android fallback-font picker, preventing garbage collection from disrupting non-Latin text rendering. The shared implementation covers both Android runtimes.

Changes:

• Keep a strong reference to the fallback picker until clearFallbackFonts().
• Add a Thai-text reproducer that repeatedly loads Kanit to trigger garbage collection before rendering.

File	Description
example/​src/​reproducers/​Issue369FontPickerGC.tsx	Adds a GC-stress reproducer with Start and Reset controls.
android/​src/​main/​java/​com/​margelo/​nitro/​rive/​HybridRiveFontConfig.kt	Retains the installed fallback picker and releases it when fonts are cleared.

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

Reset and restart can let a cancelled run resume after an await, corrupt progress, or mount ThaiText before the replacement run completes setup, requiring per-run cancellation checks or serialized restarts.

No open issues 🎉

1 previously missed issue

In code that hasn't changed since last review

Prevent stale run from resuming after reset and restart

example/​src/​reproducers/​Issue369FontPickerGC.tsx:43

Reset followed by Start reuses running.current, allowing an older run to resume after an await and update progress or mount ThaiText before the replacement run finishes fallback setup and GC churn. Reset alone can also leave the cancelled run reporting churning with 250 loads. Use a per-run generation token invalidated by reset/unmount and checked after each await, or serialize restarts until the previous run exits.

2 resolved since last review

• Cancel and serialize superseded font setup runs
• Synchronize fallback font picker publication and retention

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

The reproducer can restart font setup after Reset or unmount and leaves process-wide fallback fonts installed when navigating away.

No open issues 🎉

2 previously missed issues

In code that hasn't changed since last review

Clear global fallback fonts when leaving the page

example/​src/​reproducers/​Issue369FontPickerGC.tsx:83

Navigating away without pressing Reset leaves Kanit installed as the process-wide fallback: cancel() only invalidates the run, while the new native strong reference keeps the picker and its fonts alive. Subsequent example pages therefore inherit this reproducer's font configuration. Please also enqueue clearFallbackFonts() during cleanup, after cancelling the run, so leaving the page removes its global side effects.

Prevent reset or unmount from restarting after font clearing

example/​src/​reproducers/​Issue369FontPickerGC.tsx:103

If Reset is pressed while this Start handler awaits native font clearing, the handler still resumes and creates a fresh run, overriding Reset and eventually mounting the view again. Unmounting during the same wait can also restart font setup. Capture the run ID after invoking reset() and check it before calling start() so cancellation also covers this pending restart.

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

No active review issues remain for the Android fallback-font picker retention change.

No open issues 🎉

_{Review effort: Balanced}

[HayesGordon]

LGTM!