Haze Performance

Haze Performance — Platform Support & Optimization

Instructions

1. Input Scale — Primary Optimization

Reduce source rendering resolution before applying the blur, then scale back up.

Modifier.hazeEffect(state = hazeState) {
    inputScale = HazeInputScale.Auto
    blurEffect { /* ... */ }
}

Reduces Haze cost by 5-20% (Android benchmark), translating to ~3-5% total frame duration reduction.

2. Progressive Blur vs Masking

Prefer masking for most cases. Use progressive only when the visual difference matters.

3. Platform Backend Selection

Haze auto-selects the optimal backend per platform:

4. Android 12/12L Workarounds

Only linear gradient progressive is natively supported. Force performance fallback:

blurEffect {
    progressive = HazeProgressive.verticalGradient(
        startIntensity = 1f, endIntensity = 0f,
        preferPerformance = true  // Use mask instead of multi-draw
    )
}

Other progressive types (RadialGradient, Brush) always fall back to masks on API 31-32.

5. Android 11 and Below — RenderScript

Blur is disabled by default (falls back to scrim). Enable explicitly:

blurEffect { blurEnabled = true }

Drawbacks:

• Slower — requires copying content for RenderScript processing
• Frame-behind — background thread processing means updates lag by 1+ frames
• Skips frames — only processes one frame at a time; drops new draws during processing
• Haze uses ViewTreeObserver.OnPreDrawListener for manual invalidation (more global than ideal)

6. Android 12 and Below — Manual Invalidation

Haze subscribes to ViewTreeObserver.OnPreDrawListener for layer invalidation when content changes. This is more global than needed (fires on any draw, not just hazeSource nodes) but should not cause performance issues. Disable blur if needed:

blurEffect { blurEnabled = false }

7. Benchmark Reference (Pixel 6, Android latest)

P90 frame durations. Varies by device and scenario.

Feature cost on top of Haze baseline:

8. Disable Blur Per Effect

blurEffect { blurEnabled = false }

Also disable globally at HazeState level for older APIs if needed.

9. Screenshot Testing

Android Robolectric: run at SDK 35+ for correct RenderEffect tile mode:

@Config(sdk = [35])
class MyScreenshotTest { /* ... */ }

10. Skiko Platforms (Desktop, iOS, Web)

Desktop JVM, iOS, and Web (Wasm/JS) are all Compose Multiplatform targets built on Skiko, which bundles the Skia Graphics Library. This means:

• The host platform is not particularly important to Haze — Skiko/Skia handles the abstraction.
• All Skiko targets run Haze in its optimal environment (Skia ImageFilter-based blur).
• Haze is built against the latest stable Compose Multiplatform version.
• Pre-release CMP versions are occasionally verified but not guaranteed — test thoroughly.

Key takeaway: Desktop, iOS, and Web all share the same high-quality Skia shader backend. No platform-specific caveats like Android API-level fragmentation.

11. Emulator Rendering

The RenderScript path (API ≤30) does NOT render blur on the Android Emulator. Works on physical devices only.

12. Checklist

• Use HazeInputScale.Auto or Fixed(0.5) in production.
• Prefer masking over progressive for performance.
• Test progressive on Android 12 devices if targeting that API level.
• Consider blurEnabled = false on API ≤30 unless RenderScript tradeoffs are acceptable.
• Write Macrobenchmark tests for your specific UI.
• Validate on physical devices, not just emulator (especially for API ≤30).