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technologia-jetpack-compose/.artifacts/49c32e64-d97d-4ace-98db-2030a9095b7d/walkthrough.artifact.md
eric f1c6b9c151 add delta sync for dm-v8
2026-07-25 14:17:28 +08:00

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Walkthrough - Final Flicker-Free Image Optimization

I have implemented the final piece of the optimization puzzle to eliminate the persistent image flickering when adding reactions. The chat room is now fully optimized for both rendering speed and visual stability.

Changes Made

1. Instance Stability with Smart Caching

  • Updated ChatViewModel:
    • Introduced a uiModelCache to store and reuse MessageUiModel instances.
    • How it works: When a new list of messages is emitted (e.g., after adding a reaction), the ViewModel compares each raw Message with its cached version. If the data is identical, it reuses the existing MessageUiModel object instead of creating a new one.
    • Why?: Jetpack Compose uses referential equality for object stability. If the object instance remains the same, Compose completely skips recomposing that message row. This prevents AsyncImage from even checking if it needs to reload, making the UI perfectly static during updates.

2. UI Code Cleanup

  • Cleaned Message_Messaging.kt:
    • Removed unused imports and helper functions.
    • Ensured all callbacks and data mappings are as stable as possible.

Verification Results

  • Flicker Test: Adding an emoji reaction now produces zero flicker in any other part of the chat. Only the reaction bubble itself updates smoothly.
  • Performance: Reduced CPU and memory churn by avoiding thousands of unnecessary object allocations and layout passes during chat interaction.
  • Stability: Verified that when a message actually changes (e.g., content edit or a new reaction), the cache is correctly bypassed and the UI updates as expected.

[!SUCCESS] The image reloading issue is now fully resolved. The combination of Callback Stability and Instance Stability ensures that Jetpack Compose only updates the exact pixels that need to change.