davide.trentin/KMPCharts
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Author SHA1 Message Date
Trentin Davide
0e3360e4a0 perf(chart-realtime): cut per-frame render CPU on realtime chart 
Profiling (Pixel 7 + SM-T819) showed the chart CPU-bound in Skia
analytic-AA path fill plus a full-buffer copy on every frame.

- LineSignalRenderer: draw the signal polyline with anti-aliasing off,
  via a cached common Paint + drawIntoCanvas (KMP-safe, no nativeCanvas).
  Flips Skia from CPU coverage-mask raster to GPU tessellation;
  configured strokeWidth still honored. Removes the old Stroke cache.
- TieredBuffer/CircularBuffer: replace the full ~60k-sample copy+scan in
  the draw hot path with an O(log n) bisect window read (copyWindow).
  Output byte-identical (equivalence tests incl. ring-wrap + edges).
- RealtimeChart: split the single Canvas into a cold layer (Y-axis line,
  grid, labels) and a hot layer (signal, X-axis, crosshair) so per-frame
  TextMeasurer layout stops running every frame. Y range stabilized to
  the tick grid and shared by both layers (signal never clips).
- minSdk 26 -> 24.

Renderer unit test moved commonTest -> iosTest (Compose Paint delegates
to a non-mockable android.graphics.Paint stub on the JVM host; Skiko
backs it for real). Verified on SM-T819 (release): frame time 150ms ->
48ms, ~10 -> ~31 fps at full 8x200 Hz load.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
 2026-07-23 11:39:00 +02:00
Trentin Davide
af6814e2b8 feat(chart): v0.5.0 architecture + interaction 
Ships v0.5.0 via kmp-manager 6-phase flow. 13 plan tasks (D1, T1-T10, D3, D4),
14 agent calls, 6 P-groups. 107 → 207 tests on iosSimulatorArm64.

Toolchain (D1):
- Kotlin 2.1.0 → 2.3.21
- Compose-Multiplatform 1.8.0 → 1.11.0
- Android Gradle Plugin 8.7.3 → 9.2.0
- Gradle 8.11.1 → 9.5.1
- coroutines 1.9.0 → 1.11.0, kotlin-test → 2.3.21
- Drop kotlinx-datetime; use stdlib kotlin.time.Clock
- Drop iosX64 target (Compose-MP 1.11.0 has no ios_x64 variant)

Architecture (T1-T6, T10):
- TieredBuffer.snapshotWindow: bisect-based windowed snapshot
- New lod/ package: LodStrategy interface + MinMax/Lttb/MinMaxLttb impls
  (MinMaxLttb SOTA per arXiv 2305.00332, 1.80× faster than pure LTTB)
- New render/SignalRenderer: public interface + LineSignalRenderer object
- New render/AxisFormatter: 4 default impls (Time, Decimal, DateTime, Unit)
- HARD BREAK: deleted LodMode, LodDecimator, ChartConfig.targetFps
- ChartConfig split: DataConfig + AxisConfig + RenderConfig + FrameRate sealed
- @Immutable/@Stable on all public types (0 unstable)
- RealtimeChartState.clear() API

Interaction layer (T7):
- New interaction/ package
- ChartInteractionState + rememberChartInteractionState()
- ViewportMode sealed: Following / Frozen / History(anchorMs)
- Pinch zoom + drag pan + tap crosshair gestures
- Swipe-to-edge resumes Following
- InverseProjection: pixel → ms + bisect nearest-sample

Perf finishing (T8, T9, D3):
- LineSignalRenderer Stroke cache, AxisRenderer TextStyle cache
- resolveYRange Pair<Float,Float> → FloatArray out-param
- RealtimeChartState.signalsArray cached (invalidated on add/remove only)
- LTTB upper-bound aligned to half-open [start, start+windowMs) semantic

Correctness (D4):
- NumberFormat.formatFixed Long overflow guard @ |v|≥1e19

ABI baseline regenerated:
- chart-realtime.api: 161 → 428 LOC
- chart-realtime.klib.api: 211 → 501 LOC

Modules touched: chart-realtime (lib), app (consumer), gradle (toolchain),
.paul (state).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
 2026-05-22 00:05:43 +02:00