@blueprint-chart/lib

Core library for Blueprint Chart — a DSL-driven charting engine built on D3.

Install

npm install @blueprint-chart/lib

Quick start

Node — write SVG and PNG to disk

import { render } from '@blueprint-chart/lib'
import { writeFile } from 'node:fs/promises'

const chart = await render(bpc)
await writeFile('chart.svg', await chart.toSvg())
await writeFile('chart.png', await chart.toPng({ width: 1200 }))

Browser — mount and step scenes

const { mount, scene } = await render(bpc)
mount('#chart')   // element or selector
scene(2)          // advance to scene index 2

The simplest way to render a chart is the IIFE runtime, which auto-scans the document for embedded chart definitions and renders each one inline (inside a sandboxed iframe inserted before the script tag):

<script src="https://unpkg.com/@blueprint-chart/lib/dist/lib/lib.iife.js"></script>

<script type="application/blueprint-chart">
  chart MyChart {
    data { values = "[[0,1],[1,4],[2,2]]" }
    series "line" { color = "steelblue" }
  }
</script>

For programmatic use in an ES module project, the lib exposes the underlying primitives: parse (DSL → AST), validateChart (AST → ValidationResult with typed errors and warnings), buildChartOptions (AST → render options), createFrame/createCanvas, and the chart registry (registerChart, getChart). See src/index.ts for the full public API.

DSL Grammar

The chart DSL is defined by a PEG grammar in src/dsl/grammar.peggy and compiled to src/dsl/grammar.js using Peggy.

EBNF Overview

Chart       = "chart" Identifier "{" ChartMember* "}"
ChartMember = DataBlock | Colorize | AreaFill | Annotation | Series | Scene | Property

DataBlock   = "data" "{" Property* "}"
Colorize    = "colorize" String "{" Property* "}"
AreaFill    = "area-fill" String String "{" Property* "}"
Annotation  = "annotation" String "{" Property* "}"
Series      = "series" String "{" Property* "}"
Scene       = "scene" String "{" SceneMember* "}"
SceneMember = DataBlock | Colorize | AreaFill | Annotation | Property

Property    = PropertyKey "=" PropertyValue
PropertyKey = String | Identifier
PropertyValue = Number "%" | Number | String | Identifier

Identifier  = [a-zA-Z_#][a-zA-Z0-9_#-]*
Number      = [0-9]+("."[0-9]+)?
String      = '"' (EscapeSequence | [^"\\])* '"'

Example

chart horizontal-bar {
  title = "Revenue by Region"
  sort = descending

  data {
    "North America" = 75%
    "Europe" = 53.85%
    "Asia" = 44%
  }

  colorize "North America" {
    color = "#e53e3e"
    label = "Leader"
  }

  scene "Focus" {
    sort = ascending
    colorize "Asia" {
      color = "#38a169"
    }
  }
}

AST Node Types

Regenerating the Parser

The generated parser (src/dsl/grammar.js) is checked into git so downstream packages can import lib source directly without a build step.

To regenerate after editing grammar.peggy:

pnpm --filter @blueprint-chart/lib run generate:parser

This also runs automatically before build and test via prebuild/pretest hooks.

Color Palettes

The built-in color palettes are curated from pypalettes by Joseph Music, a collection of 2700+ color palettes for data visualization. Licensed under MIT.