fix: decode bitmaps off main thread in ImageElement #33
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I forgot to mention. |
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Hi @frankjoshua, thank you for your contribution! We’ll review it and I’ll get back to you soon. |
- Combined off-main-thread bitmap decoding improvement with master's API changes - Preserved the produceState + Dispatchers.Default pattern for background decoding - Updated to use getAsset() instead of getForCurrentSystemTheme() - Added context parameter to getBitmap() call - Updated property access to use image?.main?.source?.javaClass
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Rebased to 3.10.0. This keeps test integration StrictMode-safe (prevents false positives) with no runtime/API changes. Resubmitting since last release didn’t merge—would appreciate inclusion this time. |
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Fix: Avoid decoding bitmaps on the main thread
Summary
This PR updates
ImageElementto decode bitmaps off the main thread. Previously, bitmap decoding happened inside arememberblock during composition, which could cause jank or dropped frames — especially with larger assets.The fix moves the decoding logic into a background coroutine (
Dispatchers.Default), keeping everything else (alignment, scaling, tint) intact. This change improves performance and helps keep the UI thread smooth.Why it matters
Decoding on the main thread is risky, particularly on lower-end devices or when rendering paywalls with high-res assets. This update keeps composition lightweight and improves responsiveness across the board.
Implementation Notes
withContext(Dispatchers.Default).getBitmaplogic or behavior.Suggestion: Consider moving to Coil
As a future improvement, I’d recommend exploring Coil. It’s designed for Compose, handles background decoding out of the box, and brings built-in caching, lifecycle awareness, and error handling.
That said, I realize migrating away from
getBitmapmay be tricky since it's used in other places like Modifiers — but it could be worth considering long term.