Introduction

Relevant source files

The following files were used as context for generating this wiki page:

• README.md
• Sources/SwiftDitherKit/SwiftDitherKit.docc/SwiftDitherKit.md
• Sources/SwiftDitherKit/DitherCartesianCharts.swift
• Sources/SwiftDitherKit/DitherTypes.swift
• Sources/SwiftDitherKit/DitherMath.swift
• Sources/SwiftDitherKit/DitherMotion.swift
• Sources/SwiftDitherKit/DitherAccessibility.swift
• Sources/SwiftDitherKit/SwiftDitherKit.docc/InteractionAndAccessibility.md
• Sources/SwiftDitherKit/SwiftDitherKit.docc/GettingStarted.md

SwiftDitherKit is a dependency-free SwiftUI library designed for rendering charts using ordered-dither textures. It provides a variety of chart types, including area, line, bar, pie, donut, radar, and sparkline views. The library is based on Dither Kit and focuses on providing high-performance, aesthetically unique visualizations by rendering and caching dithered images away from the main actor.

Sources: README.md:1-10, Sources/SwiftDitherKit/SwiftDitherKit.docc/SwiftDitherKit.md:1-15

The architecture separates data definitions, geometric calculations, and asynchronous rasterization. It emphasizes native integration with SwiftUI, supporting features like dynamic selection, accessibility descriptors, and motion effects that respect system settings.

Sources: Sources/SwiftDitherKit/SwiftDitherKit.docc/InteractionAndAccessibility.md:36-45, Sources/SwiftDitherKit/DitherCartesianCharts.swift:346-355

Core Chart Components

The library categorizes charts into two primary families: Cartesian and Polar. These components share a common design pattern where high-level SwiftUI views wrap specialized renderers and interaction layers.

Supported Chart Families

Category	Chart Types	Description
Cartesian	Area, Line, Bar, Sparkline	Uses X and Y axes for data representation. Supports stacking and overlaid modes.
Polar	Pie, Donut, Radar	Uses radial and angular coordinates. Supports inner radius ratios for donut charts.

Sources: Sources/SwiftDitherKit/SwiftDitherKit.docc/SwiftDitherKit.md:17-30, Sources/SwiftDitherKit/DitherCartesianCharts.swift:1-180

Data Structures

The system relies on three primary data structures to define chart content:

• DitherDatum: Represents a single category (e.g., a month on the x-axis) and contains a dictionary of values mapped to series IDs.
• DitherSeries: Defines the visual configuration (color and texture variant) for a specific data series across multiple data points.
• DitherSlice: Used for polar charts (Pie/Donut) to represent individual segments.

Sources: Sources/SwiftDitherKit/DitherTypes.swift:80-136

Architecture and Data Flow

SwiftDitherKit utilizes an asynchronous rendering pipeline to ensure the main thread remains responsive. When data or view size changes, the library computes the necessary geometry and requests a new rasterized image.

Interaction and Selection Logic

Charts support interaction through tap gestures on marks (polygons, bars, or wedges) or via the legend. Selection state is managed through SwiftUI Binding<String?>.

Visual Customization

The library offers extensive options for controlling the appearance and behavior of charts through the DitherCartesianOptions and DitherPolarOptions structures.

Formatting and Bloom

• DitherValueFormat: Provides locale-aware formatting for axes, tooltips, and VoiceOver. Options include numeric, compact, percent, and currency formats.
• DitherBloom: Adds a glow effect behind the rasterized chart. Levels include off, low, high, and aura.
• DitherVariant: Controls the fill pattern of the dithered area, such as gradient, dotted, hatched, or solid.

Sources: Sources/SwiftDitherKit/DitherTypes.swift:51-66, Sources/SwiftDitherKit/DitherCartesianCharts.swift:5-30

Motion and Transitions

Charts feature built-in animations for entrance and data changes.

• Crossfades: Used when data changes but the chart type remains the same.
• Sparkles: Area, line, and sparkline charts display occasional idle "sparkles" for visual interest.
• Reduce Motion Support: When system "Reduce Motion" is enabled, movements are replaced by short opacity fades, and sparkles stop blinking.

Sources: Sources/SwiftDitherKit/DitherMotion.swift:1-30, Sources/SwiftDitherKit/DitherSparkles.swift:1-127

Accessibility

SwiftDitherKit integrates with Apple's chart accessibility descriptor APIs. This ensures that even though the charts are rendered as pixel rasters, assistive technologies like VoiceOver can interpret the data points, series names, and selection status.

Configuration

Developers use DitherAccessibility to provide semantic context:

• title: Concise name for the chart.
• summary: Description of the chart's purpose.
• categoryAxisLabel: Label for categories (e.g., "Months").
• valueAxisLabel: Label for the numeric axis (e.g., "Revenue").

Sources: Sources/SwiftDitherKit/DitherAccessibility.swift:1-24, Sources/SwiftDitherKit/SwiftDitherKit.docc/InteractionAndAccessibility.md:22-34

Conclusion

SwiftDitherKit provides a specialized charting solution for SwiftUI developers looking for a unique "ordered-dither" aesthetic without sacrificing performance or accessibility. By combining background rasterization with standard SwiftUI interaction patterns, it offers a robust framework for both live application interfaces and static offscreen image generation.

Sources: Sources/SwiftDitherKit/SwiftDitherKit.docc/GettingStarted.md:46-55