nichart 1.0.1

Beautiful, animated, theme-aware charts for Flutter with gorgeous defaults rendered with pure Dart on every platform.

Changelog

1.0.1

• Fix: builder tooltips (ChartTooltip(builder: ...)) now stay inside the chart bounds — flipped to the left of the anchor near the right edge and clamped on both axes, instead of overflowing off-screen for points close to an edge.

1.0.0

First stable release. The public API is now covered by semantic versioning: breaking changes only in major releases.

• Annotations: BandAnnotation (a filled wash between two values — a target range, a time window) and LineAnnotation (a solid or dashed reference line — a threshold, an event moment), on either axis via Chart(annotations: [...]). Bands paint behind the grid, lines over the series; annotations never affect the automatic domain bounds and are invisible to interaction.
• NumericAxis.ticks: explicit tick positions overriding the nice-tick generator, for domains with conventional divisions (hours of a day — 0/6/12/18/24). Out-of-domain ticks are skipped.
• ChartController.plotArea: the plot rectangle in chart-local pixels, updated after each layout — lets surrounding widgets align exactly with the plot (shared-axis strips, external legends, overlays).
• Series.interactive: opt a series out of crosshair snapping, hover markers and tooltips — for decorative overlays that must never steal the crosshair. Painting is unaffected.
• Donut interaction: segments are hit-testable — hovering (mouse) or long-pressing (touch) shows a halo on the segment plus a tooltip with its value and share of the total; ChartTooltip.builder receives the segment as a HoveredPoint. DonutChart enables the tooltip by default.
• ChartLegend: a legend widget fed the same series list as the chart, resolving labels and colors identically (palette order, explicit colors, context-gray styles); lists segments for a DonutSeries.
• Accessibility: charts, donuts and sparklines now carry semantic labels. By default a description is composed from the chart type and series labels (segment names and values for donuts); override with semanticLabel: on Chart, DonutChart and Sparkline.
• Data-change morphing: unmatched new scatter points now fade in instead of appearing instantly.
• Hover over sorted series uses binary search — crosshair scrubbing stays instant on 500k-point charts.
• Series.pointIdAccessor: stable per-point identities for morphing, so inserting or removing points animates the survivors correctly instead of shifting everything by index. Matching rules are documented on ChartAnimation.
• Rubber-band overscroll now springs back with a short eased glide (respects reduced motion) instead of snapping instantly.
• BarStyle.mutedOpacity configures how far non-emphasized bars dim.
• The mouse cursor is precise only while the crosshair is engaged over data, and defers elsewhere.
• Continuous integration: analyze, format check, full test suite (goldens pinned to Windows rasterization), a Chrome-runtime pass of all non-golden tests, publish dry-run and example web build on every push.
• API surface tightened before the freeze (breaking vs 0.6.0): the series painters, BarEntry and CoordinateSpace are no longer exported (they were unusable implementation details — Series is sealed); LineStyle.smooth removed (identical to LineStyle(area:)); DomainWindow is now a class (with width) instead of a record typedef.

Deliberately deferred (additive when they land, no breaking changes expected): horizontal bars, LogScale, right-to-left layout, PNG/SVG export via PictureRecorder.

0.6.0

Milestone M6 — polish & ship.

• DonutSeries joins the sealed series hierarchy: 72% cutout by default (0 = pie), 2 px surface gaps between segments, small corner radius on segment ends, clockwise sweep entrance, value morphing aligned by category. Palette colors assign per segment in display order.
• DonutChart convenience widget with a center: slot for hero numbers. The slot is constrained to the cutout hole (scaling content down when it would not fit), and DonutStyle.radius pins the outer radius explicitly when the ring should leave more room.
• Sparkline / Sparkline.bars: axis-less mini charts from a plain List<double> — smooth gradient line or rounded mini bars with emphasizeLast:, theme-aware, zero configuration.
• Gallery completed: Dashboard (KPI tiles + hero chart + custom legend), Bars & parts (donut with center hero), Sparklines, Theming (automatic dark mode + white-label ChartThemeScope demo), alongside the existing Lines/Scatter/Motion/Interact/Stress pages.

0.5.0

Milestone M5 — scale.

• Layered repaint architecture: the chart renders as three compositor-isolated layers (grid/axes, series, interaction), each a repaint boundary. Moving the crosshair repaints only the interaction layer — never the series (covered by a regression test asserting the dirty flags).
• LTTB (Largest-Triangle-Three-Buckets) downsampling, on by default: line/area series beyond ~2× the plot width in points are reduced before painting. Downsampling.auto() / .none() / .fixed(n) per series; hover and tooltips always see the raw data. Exposed as lttbDownsample for direct use.
• Pan/zoom over large series stays cheap: point resolution, stacking and extents are cached across window changes; sorted series are sliced to the visible window (binary search) before downsampling, so zooming in reveals full detail.
• Scatter series above ~1500 points draw as a single Canvas.drawRawPoints batch into a reused Float32List — no per-frame allocations.
• Stress-test gallery page: up to 500k points with a live fps / frame-time readout and an LTTB toggle.

0.4.0

Milestone M4 — interaction.

• Hit testing and gesture recognition live on the chart's render box (the render object owns its gesture recognizers — no widget-tree gesture detector stacking).
• Crosshair: index-mode vertical hairline snapping to the nearest data x across all series, with hover markers (series-color fill, 2 px surface-color ring). Mouse hover, touch drag (when pan/zoom is off) and long-press-drag all scrub.
• ChartTooltip: dark rounded card with color chip + label + formatted value per series, flipping to stay in bounds; fully custom content via builder:. Crosshair + tooltip are now the default interactions — pass interactions: const [] to opt out.
• PanZoom: drag to pan, pinch (touch/trackpad) and Ctrl/⌘+scroll-wheel to zoom (modifier configurable), double-tap to reset. Clamped to the data domain with rubber-band edge resistance; zoom on x, y or both.
• ChartController: programmatic domain windows (setXDomain, setXDomainTime, setYDomain, reset) with gesture write-back, so listeners always see the visible window.
• Desktop polish: precise cursor over inspectable charts, grabbing cursor while panning, hover states via MouseTrackerAnnotation on the render box.
• ChartTheme gains tooltipBackgroundColor and tooltipTextStyle (derived from the color scheme's inverse surface).

0.3.0

Milestone M3 — motion.

• Entrance animations on first layout: lines/areas reveal progressively along their path (via PathMetrics), bars grow from the baseline with a per-bar stagger, scatter markers pop in. Default 600 ms, easeOutCubic.
• Data-change morphing: when data changes the chart lerps old → new point-by-point (series matched by id, points by index; bars by x position) and the axis domains glide to their new extents. Interrupted morphs continue from the currently displayed state. Default 500 ms.
• ChartAnimation configuration on Chart (duration, morphDuration, curve, entrance, morph) with ChartAnimation.none() to disable.
• Reduced motion respected automatically via MediaQuery.disableAnimations.
• Animation ticks drive repaints only (markNeedsPaint), never widget rebuilds or relayouts.
• Breaking: SeriesPainter.paint gained entrance / morph named parameters; series painters gained morphFrom fields.

0.2.0

Milestone M2 — the full cartesian series set.

• AreaSeries and LineStyle(area:) / AreaFill: the signature gradient fill fading from the series color to transparent at the baseline.
• BarSeries with BarArrangement.grouped / stacked: max 24 px thick, rounded on the data end only, stacked segments separated by a 2 px gap (never a stroke), positives stack up and negatives down. emphasizedIndex highlights one bar and mutes its siblings.
• ScatterSeries with slightly translucent markers.
• TimeAxis + TimeScale: calendar-aware ticks (whole minutes, midnights, month starts) with granularity-matched labels (14:30, Mar 5, 2026).
• CategoryAxis + CategoryScale band scale — inferred automatically for CategoryPoint data, so Chart(series: [BarSeries(data: weekCounts)]) needs zero axis configuration.
• SeriesEmphasis: highlight one series at full saturation (painted on top), mute the rest to 30%.
• Bar/area charts automatically include zero in the y domain.
• Breaking: Series.createPainter removed (painter construction is internal); Series.xAccessor is now nullable (hasXAccessor / hasCategoryAccessor probe availability); CoordinateSpace.xScale is typed Scale<double>.

0.1.0

Initial release (milestone M1 — core).

• Chart widget backed by a custom RenderBox (no gesture-detector or CustomPaint stacking), with Chart.line one-liner convenience constructor.
• Cartesian coordinate system (CoordinateSpace) with NumericScale and nice-tick generation.
• LineSeries with Fritsch–Carlson monotone cubic interpolation (no overshoot), 2 px round-capped strokes by default, and LineStyle.context() for muted dashed comparison series.
• Horizontal-hairline-only grid, minimal axes (no y-axis line, no tick marks), 11 px tabular-figure tick labels.
• ChartTheme with light() / dark() / fromColorScheme() factories, ChartThemeScope inherited override, and automatic adaptation to the ambient Theme.of(context) brightness with zero configuration.
• 8-color categorical palette assigned in fixed order.
• Golden and unit test suite (scales, ticks, monotone spline no-overshoot, theming, label overflow at narrow widths).