fl_chart Flutter Package
Third Party Library Integration by imaNNeo (open source)
Description
fl_chart is a Flutter data visualisation library providing bar charts, line charts, and pie/donut charts used throughout the statistics and analytics screens. Renders coordinator monthly activity bar charts, activity type breakdown donut charts, personal peer mentor stats visualisations, and the gamification Wrapped summary screens. Chosen for its strong Flutter-native implementation and accessibility semantics support.
Detailed Analysis
fl_chart is a zero-cost, MIT-licensed Flutter data visualisation library that directly enables the analytics and statistics features coordinators and peer mentors rely on to track programme effectiveness. By rendering bar charts for monthly activity trends, donut charts for activity type breakdowns, and personalised peer mentor stat visualisations entirely on-device, the organisation gains a compelling, data-driven user experience with no recurring vendor costs and no external data transmission. The gamification Wrapped summary screens — a key differentiator requested by NHF and HLF — are powered by this library, strengthening member engagement and programme retention. Because all rendering is local, there are no API dependencies that could create outages, and the open-source nature of the library eliminates vendor lock-in risk.
The sole cost consideration is development time for custom theming to align with organisational design tokens.
fl_chart is a well-maintained open-source package (>=0.66.0) requiring Dart SDK >=3.0.0, which aligns with the project's existing Flutter stack and introduces no new external service dependencies or procurement overhead. Integration complexity is low to medium: seven components depend on the library (444-fl-chart-adapter, 436-monthly-activity-bar-chart, 437-activity-type-donut-chart, 121-activity-chart-widget, 435-coordinator-stats-dashboard-screen, 439-personal-stats-view, 512-activity-type-breakdown-widget), meaning thorough coordination of the FlChartAdapter abstraction layer is essential to prevent regressions across screens. The main delivery risk is custom chart theming effort, which should be scoped into the design token implementation sprint. No external API keys, rate limits, or third-party onboarding are required, removing external blockers.
Testing should validate empty-state handling and frame-rate performance targets (< 100ms render for 12 months of data). No ongoing maintenance SLA is required beyond Flutter SDK compatibility updates.
fl_chart integrates as a Flutter SDK dependency (^0.66.0) and is abstracted behind the 444-fl-chart-adapter component, which normalises application data models into fl_chart's BarChartData, PieChartData, and LineChartData structures with safe defaults for null or empty datasets. All rendering is synchronous and device-local — no network calls, no authentication, no rate limits. Empty-state widgets are shown defensively when chart data is null. Performance target is < 100ms render time for up to 12 months of data; frame rate should be monitored via Flutter DevTools performance overlay during QA.
Configuration options include animation duration, touch interaction callbacks for drill-down interactions, and accessibility semantics labels (critical for the target user base). The statistics data table serves as the fallback when chart rendering fails. Dart SDK >=3.0.0 constraint must be enforced in pubspec.yaml. No environment variables required.
Using Components (7)
Dependencies (2)
Authentication
| Type | None |
Configuration
Error Handling
Monitoring
Performance
| Latency | < 100ms for chart render with up to 12 months of data |
| Availability | Device-local rendering — no network dependency |
Cost Implications
| Pricing Model | Free open-source (MIT licence) |