Documentation #

• Added a demo screenshot of the ECG waveform to the README and the pub.flutter-io.cn screenshot gallery.

Added #

• First stable release published to pub.flutter-io.cn.

Added #

• EcgMonitor widget — Drop-in animated ECG/heartbeat monitor for Flutter
• EcgMonitorConfig — Immutable configuration object with copyWith() support
• EcgGridPainter — Static ECG-paper grid background (GPU-cached via RepaintBoundary)
• EcgTrailPainter — Animated phosphor trail with cursor dot
• Zero per-frame allocations — Ring buffer + pre-baked LUTs for optimal performance
• Authentic PQRST waveform — 1000-point Gaussian lookup table for realistic cardiac events
• Heart Rate Variability (HRV) — Organic time-warping via dual sine waves
• Breathing baseline — Slow sinusoidal drift simulating respiratory artifact
• Ambient screen flash — Subtle radial glow when cursor spikes off baseline
• Theme-aware tip color — Auto white/black87 based on Brightness, fully overridable
• Configurable parameters:
  • heartRateBPM — Beats per minute (default: 60.0)
  • beatDurationSeconds — PQRST waveform duration (default: 0.35)
  • cursorSpeedPixelsPerSecond — Cursor travel speed (default: 40.0)
  • lineThickness — Trail stroke width (default: 1.0)
  • cursorThickness — Cursor dot radius (default: 1.0)
  • glowThickness — Cursor glow halo radius (default: 1.1)
  • beatSpikeAmplitude — R-spike height in pixels (default: 8.0)
  • gapMinPixels / gapMaxPixels — Gap distance constraints (default: 15/100)
  • gridMinorSpacing — Grid line spacing (default: 15.0)
  • gridMajorEvery — Major line frequency (default: 5)
  • breathingAmplitude — Baseline breathing wave amplitude (default: 0.8)
  • breathsPerMinute — Breathing rate (default: 15.0)
  • color — Trail base color (default: Color(0xFF00FF00))
  • tipColor — Cursor tip color (default: null = light/dark mode-dependent)

Documentation #

• README.md — Quick start guide, configuration table, advanced usage examples
• ARCHITECTURE.md — Deep dive into optimization techniques (O1-O7), rendering pipeline, state management
• MIGRATION.md — Migration guide from inline implementation to package
• Example app — Three demo configurations (resting 60 BPM, elevated 100 BPM, bradycardia 27 BPM)

Performance Optimizations #

• O1: Pre-baked Heartbeat LUT — 1000-element Float64List computed once at class load
• O2: Ring Buffer Trail Storage — Float64List indexed by pixel X, double.nan for empty slots
• O3: Distance-to-Paint LUT — Pre-mapped integer distance → paint bucket index
• O4: Pre-built Paint Lists — 100 Paint objects covering full dim→bright gradient
• O5: GPU-cached Static Grid — RepaintBoundary wrapper for zero-repaint background
• O6: Targeted Gap Cleanup — O(gap) erase loop vs O(n) map scan
• O7: Skipped-pixel History Fill — Back-calculates missed pixels on dropped frames

Technical Details #

• Minimum SDK: Dart >=3.0.0 <4.0.0, Flutter >=3.10.0
• Zero external dependencies (Flutter SDK only)
• Wall-clock accurate timing via DateTime.now() — independent of frame rate
• Cursor wraps seamlessly from right edge to left edge
• Trail persists across painter recreation (static state)