Added #

Chart Types

• FusionLineChart — Line chart with straight or smooth curved lines (Bezier/Catmull-Rom splines)
• FusionBarChart — Bar chart for categorical data comparison
• FusionStackedBarChart — Stacked bar chart for cumulative data visualization
• FusionPieChart — Pie and Donut charts with smart labels, selection, and center content

Series Features

• FusionLineSeries — Line series with configurable width, curves, dash patterns
• FusionBarSeries — Bar series with customizable bar width, spacing, and border radius
• FusionStackedBarSeries — Stacked bar series for cumulative visualization
• FusionPieSeries — Pie series with customizable colors, strokes, and corner radius
• FusionAreaSeries — Area fill support with gradient backgrounds
• Series visibility toggling
• Gradient support (linear gradients)
• Shadow/glow effects
• Data labels with custom formatters
• Marker shapes (circle, square, triangle, diamond, pentagon, hexagon)

Theming System

• FusionChartTheme — Abstract theme interface
• FusionLightTheme — Professional light color scheme (default)
• FusionDarkTheme — Dark mode theme
• Full customization: colors, typography, dimensions, animations, shadows
• WCAG 2.1 AA compliant contrast ratios

Configuration

• FusionChartConfiguration — Central configuration with builder pattern
• FusionAxisConfiguration — Axis customization (min, max, intervals, labels)
• FusionTooltipConfiguration — Tooltip behavior and styling
• FusionCrosshairConfiguration — Crosshair appearance and dismiss strategies
• FusionZoomConfiguration — Zoom limits and behavior
• FusionLegendConfiguration — Legend positioning and styling

Interactions

• Touch/tap detection with nearest point finding
• Long-press for crosshair activation
• Hover support (desktop)
• Pinch-to-zoom
• Pan/drag navigation
• Trackball modes: none, follow, snap, magnetic
• Haptic feedback integration
• Configurable dismiss strategies (onRelease, afterDuration, never)

Axis System

• Numeric axis with auto-scaling
• DateTime axis with intelligent interval selection
• Category axis support
• Custom label formatters
• Axis bounds calculation with nice numbers algorithm
• Multiple range padding strategies

Performance Optimizations

• FusionPaintPool — Object pooling for Paint instances (90% GC reduction)
• FusionShaderCache — Gradient shader caching
• FusionRenderCache — General render cache
• FusionRenderOptimizer — Dirty region tracking and path caching
• LTTBDownsampler — Largest Triangle Three Buckets algorithm for 10K+ points
• Coordinate system caching with hash-based invalidation
• Pixel snapping for crisp rendering on high-DPI displays

Data Handling

• FusionDataPoint — Immutable data point with x, y, label, metadata
• DataValidator — Validates and cleans data (NaN, Infinity, duplicates)
• Data statistics calculation (min, max, mean, range)
• Range clamping support
• Automatic sorting by X coordinate

Rendering Engine

• FusionCoordinateSystem — Immutable coordinate transforms with pixel snapping
• FusionPathBuilder — Smooth path generation (Bezier, Catmull-Rom, Douglas-Peucker)
• FusionChartPainterBase — Template method pattern for painters
• Dashed line support with custom patterns
• Area fill with baseline

Utilities

• FusionColorPalette — 6 color palettes (Material, Professional, Vibrant, Pastel, Warm, Cool)
• FusionDataFormatter — Number and date formatting utilities
• FusionMathematics — Spline calculations, interpolation
• FusionResponsiveSize — Responsive sizing helpers

Documentation

• Comprehensive dartdoc comments
• Example application with 20+ demos
• README with quick start guide

Notes #

• Minimum Flutter SDK: 3.22.0
• Minimum Dart SDK: 3.9.0
• Dependencies: intl for formatting

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Added #

Live Chart Streaming

• FusionLiveChartController — Real-time data streaming with automatic viewport management
  • addDataPoint() / addDataPoints() for streaming data
  • pause() / resume() for stream control
  • Configurable viewport modes: sliding, expanding, fixed
  • Auto-scroll with configurable window duration
• LTTB Downsampling — Largest Triangle Three Buckets algorithm for DownsampledPolicy
  • Archive storage for older data combined with recent full-resolution points
  • Maintains visual fidelity while reducing point count
• Live Tooltip Probe Mode — Real-time data tracking at fixed screen position
  • updateLiveTooltip() method for proper tooltip updates during streaming
• FusionLiveChartMixin — Reusable mixin for live streaming functionality

Crosshair Enhancements

• FusionCrosshairLabelFormatter — Custom axis label formatting callback
• FusionCrosshairLabelBuilder — Custom label widget builder
• InteractionAnchorMode — Persistent crosshair anchoring modes

Performance Optimizations

• Batch grid line and tick rendering using Path (reduces N drawLine calls to 1 drawPath)
• Cache TextPainter instances and label sizes in axis renderers
• Binary search for nearest point lookup (O(log n) vs O(n))
• Quick sorted-data detection to choose optimal search algorithm

Comprehensive Test Suite

• Added 54 new test files covering all major components
• Total test count: 3,626 tests
• Test coverage increased from ~60% to 75.86% (8,864/11,685 lines)
• Full coverage for axis renderers, tooltip system, data labels, interactive states
• Extensive tests for DST handling, render pipeline, chart themes, error boundaries

Examples

• New live_chart_showcase.dart — Comprehensive example with live streaming demonstrations

Changed #

• Removed deprecated enabled field from FusionZoomConfiguration (use FusionChartConfiguration.enableZoom)
• Removed deprecated enabled field from FusionPanConfiguration (use FusionChartConfiguration.enablePanning)
• Migrated deprecated Color.value to Color.toARGB32() throughout codebase
• Replaced unnecessary lambdas with method tearoffs for better performance
• Updated withOpacity calls to withValues(alpha:) for Flutter 3.22+ compatibility

Fixed #

• Fixed multi-series live chart tooltip incorrectly switching to first series when mouse stops moving
• Fixed dual timer inconsistency in hideTooltip() causing stale callbacks
• Added disposal protection to prevent "disposed EngineFlutterView" errors
• Resolved all lint warnings for clean static analysis

Quality #

• Pana Score: 160/160 (perfect score)
• Static Analysis: 0 issues
• All tests passing

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Added #

Programmatic Control API

• FusionChartController — Full programmatic control over zoom and pan operations
  • zoomIn(), zoomOut(), zoomToFit(), resetZoom() methods
  • panTo(), panBy() for programmatic panning
  • setZoomLevel() with animation support
  • Event streams for zoom/pan state changes
  • Attach/detach to any interactive chart

New Widgets

• FusionZoomControls — Ready-to-use zoom control widget with customizable buttons
• FusionScrollInterceptWrapper — Desktop scroll wheel zoom support with proper event handling

New Utilities

• FusionDesktopHelper — Platform detection utilities for desktop-specific behaviors
• FusionZoomAnimationMixin — Smooth animated zoom transitions with configurable curves
• FusionSelectionRectLayer — Box selection rendering for zoom-to-region functionality

Axis Configuration

• labelGenerator callback in FusionAxisConfiguration for complete control over axis label positioning
  • Receives axis bounds, available size, and orientation
  • Returns list of values where labels should appear
  • Supports use cases like:
    • Edge-inclusive labels (always show min/max)
    • Percentage-based labels (0%, 25%, 50%, 75%, 100%)
    • Powers of 10 (log-scale style)
    • Fibonacci sequence positioning
    • Custom business thresholds
    • DateTime patterns (first of month, every Monday)
    • Density-based responsive labels

Examples

• New zoom_pan_showcase.dart — Comprehensive example with 27 zoom/pan demonstrations

Changed #

• enableCrosshair default changed from true to false for cleaner out-of-box experience
  • Charts now render without crosshair by default
  • Explicitly set enableCrosshair: true to enable

Fixed #

• Fixed zoom and pan gestures being interrupted mid-interaction due to gesture recognizer recreation
• Fixed gesture recognizer caching not being populated in FusionInteractiveChartState
• Added gesture recognizer caching to FusionBarInteractiveState and FusionStackedBarInteractiveState
• Fixed unnecessary widget rebuilds during pan/zoom start that killed in-progress gestures
• Fixed FusionInteractionHandler being recreated during active gestures, which reset _lastScale and broke incremental pinch-zoom calculations
• Fixed zoom state being reset on widget rebuild — coordinate system updates during active gestures now preserve zoomed data bounds while only updating screen dimensions
• Fixed timer cleanup in multi-touch interaction tests

Deprecated #

The following fields are ignored and will be removed in v2.0.0. Use the top-level configuration flags instead:

• FusionZoomConfiguration.enabled → Use FusionChartConfiguration.enableZoom
• FusionPanConfiguration.enabled → Use FusionChartConfiguration.enablePanning
• FusionTooltipBehavior.enable → Use FusionChartConfiguration.enableTooltip
• FusionCrosshairConfiguration.enabled → Use FusionChartConfiguration.enableCrosshair

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[Unreleased] #

Planned #

• Scatter charts
• Bubble charts
• Candlestick/OHLC charts
• Radar/Spider charts
• Gauge charts
• Funnel charts
• Multiple Y-axes
• Annotations and plot bands
• Export to image (PNG, SVG)
• Accessibility improvements (Semantics)

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Version History #

Version	Date	Description
1.1.0	2026-02-19	Live chart streaming, LTTB downsampling, 75.86% test coverage
1.0.1	2026-01-13	Programmatic control API, labelGenerator, zoom/pan fixes, deprecations
1.0.0	2026-01-01	Initial release