Terminal visualization components for Ink, React CLI framework

• BarChart - Horizontal bar charts with individual row coloring and custom formatting
• StackedBarChart - 100% stacked horizontal bar charts showing percentage distribution
• LineGraph - High-resolution line graphs with multi-series support and axis labels
• Sparkline - Compact trend visualization with threshold highlighting and gradient colors
• TypeScript - Full TypeScript support with comprehensive type definitions
• Auto-width - Responsive charts that adapt to terminal width
• Gradient Colors - 8-level smooth color gradients with automatic terminal compatibility
• Performance - Optimized rendering with React.memo to prevent flickering

npm install @pppp606/ink-chart

import React from 'react';
import { render, Text, Box } from 'ink';
import { BarChart, StackedBarChart, LineGraph, Sparkline } from '@pppp606/ink-chart';

function App() {
  return (
    <Box flexDirection="column">
      {/* Bar chart with values */}
      <BarChart
        data={[
          { label: 'Sales', value: 1250 },
          { label: 'Marketing', value: 800 }
        ]}
        showValue="right"
        sort="desc"
      />

      {/* Stacked bar chart showing distribution */}
      <StackedBarChart
        data={[
          { label: 'Complete', value: 75, color: '#4aaa1a' },
          { label: 'Remaining', value: 25, color: '#d89612' }
        ]}
      />

      {/* Line graph with multiple series */}
      <LineGraph
        data={[
          { values: [10, 15, 12, 18, 14, 20], color: 'red' },
          { values: [8, 12, 16, 14, 18, 16], color: 'blue' }
        ]}
        height={5}
        showYAxis={true}
        xLabels={['Jan', 'Jun']}
      />

      {/* Simple sparkline */}
      <Sparkline data={[1, 3, 2, 5, 4, 6, 3]} />
    </Box>
  );
}

render(<App />);

Horizontal bar charts with customizable appearance and individual row colors.

<BarChart
  data={[
    { label: 'Success', value: 22, color: '#4aaa1a' },
    { label: 'Warnings', value: 8, color: '#d89612' },
    { label: 'Errors', value: 15, color: '#a61d24' }
  ]}
  showValue="right"
  width={50}
  format={(v) => `${v}%`}
/>

Props:

• data: BarChartData[] - Array of data points
• sort?: 'none' | 'asc' | 'desc' - Sort order
• showValue?: 'right' | 'inside' | 'none' - Value display position
• width?: 'auto' | 'full' | number - Chart width ('auto': natural content width, 'full': terminal width, number: fixed width)
• max?: 'auto' | number - Maximum value for scaling
• format?: (value: number) => string - Value formatter
• barChar?: '▆' | '█' | '▓' | '▒' | '░' - Bar character
• color?: string - Default color (overridden by individual BarChartData.color)

BarChartData interface:

interface BarChartData {
  label: string;
  value: number;
  color?: string; // Hex code or Ink color name
}

Stacked horizontal bar chart with two modes: 100% percentage distribution or absolute values.

// Percentage mode (default) - 100% stacked
<StackedBarChart
  data={[
    { label: 'Sales', value: 30, color: '#4aaa1a' },
    { label: 'Warning', value: 20, color: '#d89612' },
    { label: 'Error', value: 50, color: '#a61d24' }
  ]}
  width={50}
/>

// Absolute mode - showing actual values
<StackedBarChart
  data={[
    { label: 'Downloads', value: 1250 },
    { label: 'Uploads', value: 450 }
  ]}
  mode="absolute"
  max={5000}
  format={(v, mode) => mode === 'percentage' ? `${v.toFixed(1)}%` : `${v}`}
  width={50}
/>

Props:

• data: StackedBarSegment[] - Array of segments to display
• mode?: 'percentage' | 'absolute' - Display mode (default: 'percentage')
  • 'percentage': 100% stacked showing percentage distribution
  • 'absolute': Stacked bar showing actual values scaled to max
• max?: 'auto' | number - Maximum value for scaling in absolute mode (default: 'auto')
• width?: 'auto' | 'full' | number - Chart width ('auto': 40 characters default, 'full': terminal width, number: fixed width)
• showLabels?: boolean - Whether to show segment labels above bar (default: true)
• showValues?: boolean - Whether to show values below bar (default: true)
• format?: (value: number, mode: StackedBarChartMode) => string - Value formatter

StackedBarSegment interface:

interface StackedBarSegment {
  label: string;
  value: number;
  color?: string; // Hex code or Ink color name
  char?: string;  // Custom character for this segment
}

High-resolution line graph using Unicode scan line characters (⎺ ⎻ ─ ⎼ ⎽) for 5-level vertical resolution per row.

<LineGraph
  data={[
    { values: [100, 120, 115, 130, 125, 140], color: 'red' },
    { values: [90, 110, 130, 120, 140, 130], color: 'blue' }
  ]}
  width={50}
  height={6}
  showYAxis={true}
  xLabels={['Q1', 'Q4']}
/>

Output:

   140│            ⎽    ⎽─⎺
      │    ⎼⎽  ⎽⎼⎽⎽─⎺ ⎽─⎻
      │ ⎼⎼⎽ ⎽⎼⎼⎼⎽⎽⎽⎼─⎻
      │⎼──⎼⎼⎼⎼─⎺⎺⎻⎺
      │⎻⎺─⎺
    90│⎺─⎻
      └──────────────────────
       Q1                  Q4

Props:

• data: LineGraphSeries[] - Array of data series (each with values and optional color)
• width?: 'auto' | 'full' | number - Chart width
• height?: number - Chart height in rows (default: 10, each row = 5 vertical levels)
• yDomain?: 'auto' | [number, number] - Y-axis range
• showYAxis?: boolean - Show Y-axis labels (default: false)
• yLabels?: (string | number)[] - Custom Y-axis labels (numbers: position-based, strings: evenly distributed)
• xLabels?: (string | number)[] - X-axis labels (numbers: position-based, strings: evenly distributed)
• caption?: string - Optional caption below chart

LineGraphSeries interface:

interface LineGraphSeries {
  values: number[];
  color?: string; // Ink color name or hex
}

Compact trend visualization perfect for displaying time series data.

<Sparkline
  data={[1, 3, 2, 8, 4]}
  width={30}
  threshold={5}
  colorScheme="red"
  caption="Sales Trend"
/>

Props:

• data: number[] - Array of numeric values
• width?: 'auto' | 'full' | number - Chart width ('auto': data length, 'full': terminal width, number: fixed width)
• threshold?: number | number[] - Threshold(s) for highlighting (single or gradient)
• colorScheme?: 'red' | 'blue' | 'green' - Color scheme for gradient highlighting
• mode?: 'block' | 'braille' - Rendering mode
• caption?: string - Optional caption below chart

// 8-level smooth gradient
<Sparkline 
  data={[45, 55, 65, 75, 85, 95, 85, 75]}
  threshold={[55, 62, 68, 74, 79, 84, 89, 94]}
  colorScheme="red"
/>

<BarChart 
  data={[
    { label: 'Q1', value: 125000 },
    { label: 'Q2', value: 180000 }
  ]}
  format={(v) => `$${(v/1000)}K`}
  showValue="right"
/>

<BarChart
  data={[
    { label: 'Success', value: 85, color: '#4aaa1a' },
    { label: 'Warning', value: 12, color: '#d89612' },
    { label: 'Error', value: 3, color: '#a61d24' }
  ]}
/>

// Full Block (█)
<BarChart
  data={[{ label: 'Progress', value: 75 }]}
  barChar="█"
  max={100}
/>

// Dark Shade (▓)
<BarChart
  data={[{ label: 'Progress', value: 75 }]}
  barChar="▓"
  max={100}
/>

// Medium Shade (▒)
<BarChart
  data={[{ label: 'Progress', value: 75 }]}
  barChar="▒"
  max={100}
/>

// Light Shade (░)
<BarChart
  data={[{ label: 'Progress', value: 75 }]}
  barChar="░"
  max={100}
/>

<StackedBarChart
  data={[
    { label: 'Development', value: 45, color: '#1890ff' },
    { label: 'Testing', value: 25, color: '#52c41a' },
    { label: 'Planning', value: 15, color: '#faad14' },
    { label: 'Meetings', value: 15, color: '#f5222d' }
  ]}
  width={60}
  format={(v) => `${v.toFixed(0)}%`}
/>

Output:

Development                Testing        Planning Meetings
████████████████████████████████████████████████████████████
45%                        25%            15%      15%

Colors differentiate segments (not visible in plain text)

<StackedBarChart
  data={[
    { label: 'CPU', value: 45, color: '#1890ff' },
    { label: 'Memory', value: 30, color: '#52c41a' },
    { label: 'Disk', value: 15, color: '#faad14' }
  ]}
  mode="absolute"
  max={100}
  width={60}
  format={(v, mode) => mode === 'percentage' ? `${v.toFixed(1)}%` : `${v.toFixed(0)}`}
/>

Output:

CPU                        Memory          Disk
███████████████████████████▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒▒▒▒▒▒▒▒
45                         30              15

Try the interactive demo to see all features in action:

# Static examples - all chart features
npm run demo

The demo showcases:

BarChart Examples:

• Department performance comparison with sorting
• Multi-color status indicators (Success, Warnings, Errors)
• Different bar character styles (█, ▓, ▒, ░)

StackedBarChart Examples:

• Percentage Mode: 100% stacked bar showing percentage distribution

  Sales          Warning   Error
  ███████████████▓▓▓▓▓▓▓▓▓▓▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
  30.0%          20.0%     50.0%
  

• Project Time Allocation: Color-coded segments

  Development                Testing        Planning Meetings
  ████████████████████████████████████████████████████████████
  45%                        25%            15%      15%
  

  Each segment uses the same character (█) but different colors

• Absolute Mode: Server resource usage with actual values

  CPU                        Memory          Disk
  ███████████████████████████▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒▒▒▒▒▒▒▒
  45                         30              15
  

LineGraph Examples:

• Temperature Trend: High-resolution line with X-axis labels

                     ⎽⎼─⎺⎻⎻─⎼⎽
                  ⎽─⎻         ⎻─⎼
              ⎽⎼─⎺               ⎺─⎼
          ⎽⎼─⎺                      ⎺⎻⎼
       ⎽─⎻                             ⎺⎻⎼
   ⎽⎼─⎺                                   ⎺
   ────────────────────────────────────────
   Jan                                  Dec
  

• Multi-Series Comparison: Multiple data series with Y-axis

     160│                             ⎽    ⎽ ⎽─⎺⎺⎽⎼⎻⎺
        │                   ⎼⎽  ⎽⎼⎽⎽─⎺ ⎽─⎻⎺─⎺⎺⎻⎻⎺
        │         ⎼⎼⎽ ⎽⎼⎼⎼⎽⎽⎽⎼─⎻──⎻ ⎺⎺⎺
        │    ⎼──⎼⎼⎼⎼─⎺⎺⎻⎺
        │ ⎼⎻⎺─⎺
      90│⎺─⎻
        └────────────────────────────────────────────
         Q1                                        Q4
  

  Red and blue lines show different series (colors not visible in plain text)

Sparkline Examples:

• Server RPS (Requests Per Second) trend over 24 hours
• 8-level smooth color gradients (red, blue, green)
• Threshold highlighting with multiple gradient levels

8-level gradient highlighting with automatic terminal compatibility:

<Sparkline 
  threshold={[10, 20, 30, 40, 50, 60, 70, 80]}
  colorScheme="blue" // red, blue, or green
/>

Color Support:

• 24-bit terminals (iTerm, VSCode): Full RGB gradients
• 256-color terminals: Palette-based gradients
• 16-color terminals: Basic color fallbacks

Detection is automatic based on COLORTERM, TERM, and TERM_PROGRAM environment variables.

Components are optimized with React.memo to prevent unnecessary re-renders:

// Only re-renders when values actually change
<BarChart data={dynamicData} />

Charts can adapt to full terminal width:

<Sparkline width="full" /> // Full terminal width
<BarChart width="full" />  // Full terminal width

This package implements comprehensive security practices:

• Secure CI/CD: SHA-pinned GitHub Actions with minimal permissions
• Supply Chain Protection: Provenance attestation and OIDC authentication
• Secret Scanning: Automated detection of accidentally committed secrets
• Dependency Security: Regular security audits and automated vulnerability scanning
• Workflow Protection: CODEOWNERS file and branch protection rules

For security policy, vulnerability reporting, and detailed security information, see SECURITY.md.

MIT