MapAccessibility 1.0.1

MapAccessibility

WCAG 2.1 AA color accessibility checking for cartographic palettes. Zero dependencies — pure .NET 8+.

Check contrast ratios, simulate color vision deficiency (CVD), and score palette accessibility for maps, dashboards, and data visualization.

Install

dotnet add package MapAccessibility

Usage

using MapAccessibility;

// Contrast ratio between two colors (1.0–21.0)
double ratio = AccessibilityChecker.ContrastRatio("#1B4F72", "#FFFFFF"); // 10.53

// WCAG compliance check
bool passes = AccessibilityChecker.MeetsWcag("#1B4F72", "#FFFFFF",
    level: WcagLevel.AA, textSize: TextSize.Normal); // true

// All thresholds at once
ContrastResult result = AccessibilityChecker.FullCheck("#1B4F72", "#FFFFFF");
// result.MeetsAaNormal, result.MeetsAaLarge, result.MeetsAaaNormal, result.MeetsAaaLarge

// Simulate color vision deficiency
string simulated = CvdSimulator.Simulate("#FF0000", CvdType.Deuteranopia); // "#A58400"

// Check if two colors remain distinguishable under CVD
bool distinct = CvdSimulator.IsDistinguishable("#FF0000", "#00FF00", CvdType.Deuteranopia);

// Score a palette (0.0–1.0)
PaletteScore score = PaletteScorer.Score(
    new[] { "#1B4F72", "#2E86C1", "#AED6F1", "#FDEBD0", "#E74C3C" });

// Pre-built accessible palettes
string[] colors = AccessiblePalettes.Qualitative(5);
string[] blues = AccessiblePalettes.Sequential("blues", 7);

What's Included

Types

enum WcagLevel { AA, AAA }
enum TextSize { Normal, Large }
enum CvdType { Protanopia, Deuteranopia, Tritanopia }

readonly record struct ContrastResult(
    double Ratio, bool MeetsAaNormal, bool MeetsAaLarge,
    bool MeetsAaaNormal, bool MeetsAaaLarge);

readonly record struct PaletteScore(
    double OverallScore, double MinPairwiseContrast, double MeanPairwiseContrast,
    int CvdSafeCount, CvdType[] CvdSafeTypes, int ColorCount, string[] Warnings);

readonly record struct PaletteInfo(
    string Name, string Category, string[] Colors,
    int MinN, int MaxN, double AccessibilityScore, bool CvdSafe);

WCAG Thresholds

Why This Package

• Zero dependencies — no NTS, no System.Drawing.Common, no native binaries. Runs in Blazor WASM, MAUI, Unity, console, web API.
• Cartography-focused — scoring tuned for map fills and legends, not web buttons.
• WCAG-correct — uses the right sRGB linearization threshold (0.04045 per IEC 61966-2-1, not the common 0.03928 mistake).
• Cross-language — identical algorithms and shared test vectors across Python and R companions.

Target Frameworks

• .NET 8.0+

License

MIT

Links

• GitHub
• Report an Issue
• Contact: Chris.Lyons@ky.gov