@mlightcad/data-model

The data-model package provides the core classes for interacting with AutoCAD's database and entities. This package mimics AutoCAD ObjectARX's AcDb (Database) classes and implements the drawing database structure that AutoCAD developers are familiar with.

Overview

This package contains the core classes for defining and manipulating AutoCAD entities (e.g., lines, circles, blocks), handling entity attributes and geometric data, and storing and retrieving data from the drawing database. It uses the same drawing database structure as AutoCAD ObjectARX, making it easier for AutoCAD developers to build applications based on this SDK.

Key Features

• Database Management: Complete AutoCAD database structure with tables and records
• Entity Support: All major AutoCAD entity types (lines, circles, polylines, blocks, etc.)
• File Conversion: Built-in MIT DXF converter (AcDbNativeDxfConverter, registered by default); extensible converter registration for DWG and alternate DXF readers
• Symbol Tables: Layer, linetype, text style, and dimension style management
• Block Management: Block table and block reference handling
• Dimension Support: Comprehensive dimension entity types
• Layout Management: Paper space and model space layout handling

Installation

npm install @mlightcad/data-model
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Key Classes

Database and Base Classes

• AcDbDatabase: Main database class that contains all drawing data
• AcDbObject: Base class for all database-resident objects
• AcDbHostApplicationServices: Services provided by the host application

Symbol Tables

• AcDbSymbolTable: Base class for symbol tables
• AcDbSymbolTableRecord: Base class for symbol table records
• AcDbLayerTable, AcDbLayerTableRecord: Layer management
• AcDbLinetypeTable, AcDbLinetypeTableRecord: Linetype management
• AcDbTextStyleTable, AcDbTextStyleTableRecord: Text style management
• AcDbDimStyleTable, AcDbDimStyleTableRecord: Dimension style management
• AcDbBlockTable, AcDbBlockTableRecord: Block management
• AcDbViewportTable, AcDbViewportTableRecord: Viewport management

Entities

• AcDbEntity: Base class for all drawable objects
• AcDbLine: Line entity
• AcDbCircle: Circle entity
• AcDbArc: Arc entity
• AcDbPolyline: Polyline entity
• AcDbText, AcDbMText: Text and multiline text entities
• AcDbBlockReference: Block reference entity
• AcDbPoint: Point entity
• AcDbEllipse: Ellipse entity
• AcDbSpline: Spline curve entity
• AcDbHatch: Hatch pattern entity
• AcDbTable: Table entity
• AcDbRasterImage: Raster image entity
• AcDbLeader: Leader entity
• AcDbRay, AcDbXline: Construction line entities
• AcDbTrace, AcDbWipeout: Filled area entities

Dimension Entities

• AcDbDimension: Base class for dimension entities
• AcDbAlignedDimension: Aligned dimension
• AcDbRadialDimension: Radial dimension
• AcDbDiametricDimension: Diametric dimension
• AcDb3PointAngularDimension: 3-point angular dimension
• AcDbArcDimension: Arc dimension
• AcDbOrdinateDimension: Ordinate dimension

Objects and Layouts

• AcDbDictionary: Dictionary object for storing key-value pairs
• AcDbRasterImageDef: Raster image definition
• AcDbLayout: Layout object for paper space
• AcDbLayoutDictionary: Layout dictionary management
• AcDbLayoutManager: Layout manager for switching between layouts

File Conversion

• AcDbDatabaseConverter: Base class for file format converters
• AcDbDatabaseConverterManager: Manages registered file converters
• AcDbBatchProcessing: Batch processing utilities
• AcDbBaseWorker, acdbCreateWorkerApi: Web Worker infrastructure for parsers

DXF import is built in via AcDbNativeDxfConverter (registered by default). An optional GPL alternative is @mlightcad/dxf-json-converter. DWG import is provided by converter packages such as @mlightcad/libredwg-converter; register a DWG converter with AcDbDatabaseConverterManager before calling AcDbDatabase.read() on DWG files.

Utilities

• AcDbConstants: Database constants
• AcDbObjectIterator: Iterator for database objects
• AcDbAngleUnits: Angle unit utilities
• AcDbUnitsValue: Unit value handling
• AcDbOsnapMode: Object snap modes
• AcDbRenderingCache: Rendering cache management

Usage Examples

Database Operations

import { AcDbDatabase } from '@mlightcad/data-model';

// Create a new database
const database = new AcDbDatabase();

// Get symbol tables
const layerTable = database.getLayerTable();
const blockTable = database.getBlockTable();
const linetypeTable = database.getLinetypeTable();
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Entity Creation

import { AcDbLine, AcDbCircle, AcGePoint3d } from '@mlightcad/data-model';

// Create a line entity
const startPoint = new AcGePoint3d(0, 0, 0);
const endPoint = new AcGePoint3d(10, 10, 0);
const line = new AcDbLine(startPoint, endPoint);

// Create a circle entity
const center = new AcGePoint3d(0, 0, 0);
const radius = 5;
const circle = new AcDbCircle(center, radius);

// Set entity properties
line.setColor(1); // Red
line.setLayer('0');
circle.setLinetype('CONTINUOUS');
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Layer Management

import { AcDbLayerTableRecord } from '@mlightcad/data-model';

// Create a new layer
const layerRecord = new AcDbLayerTableRecord();
layerRecord.setName('MyLayer');
layerRecord.setColor(2); // Yellow
layerRecord.setLinetype('DASHED');

// Add layer to database
const layerTable = database.getLayerTable();
layerTable.add(layerRecord);
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Block Operations

import { AcDbBlockReference, AcGePoint3d } from '@mlightcad/data-model';

// Create a block reference
const insertionPoint = new AcGePoint3d(0, 0, 0);
const blockRef = new AcDbBlockReference(insertionPoint, 'MyBlock');

// Set block properties
blockRef.setScale(2.0);
blockRef.setRotation(Math.PI / 4);

// Add to model space
const modelSpace = database.getModelSpace();
modelSpace.appendEntity(blockRef);
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File Conversion

DXF support is registered by default via AcDbNativeDxfConverter (MIT, main-thread streaming). You only need to register a converter when you want a different DXF implementation or when reading DWG files.

import {
  AcDbDatabase,
  AcDbDatabaseConverterManager,
  AcDbFileType,
  acdbHostApplicationServices,
  AcDbOpenDatabaseOptions
} from '@mlightcad/data-model'
import { AcDbLibreDwgConverter } from '@mlightcad/libredwg-converter'

// Optional: replace the default native DXF converter (e.g. GPL worker-based parser)
// import { AcDbDxfConverter } from '@mlightcad/dxf-json-converter'
// AcDbDatabaseConverterManager.instance.register(
//   AcDbFileType.DXF,
//   new AcDbDxfConverter({
//     useWorker: true,
//     parserWorkerUrl: './assets/dxf-parser-worker.js'
//   })
// )

// DWG still requires an explicit converter registration
AcDbDatabaseConverterManager.instance.register(
  AcDbFileType.DWG,
  new AcDbLibreDwgConverter({
    useWorker: true,
    parserWorkerUrl: './assets/libredwg-parser-worker.js'
  })
)

// Read a file into the database
const database = new AcDbDatabase()
acdbHostApplicationServices().workingDatabase = database
const buffer = await file.arrayBuffer()
await database.read(buffer, { readOnly: true }, AcDbFileType.DXF)
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Font Loading

Fonts referenced by text entities are loaded on demand by the mtext renderer when a font is first needed. Viewers such as @mlightcad/cad-simple-viewer typically resolve font metadata from mlightcad/cad-data (default CDN: https://cdn.jsdelivr.net/gh/mlightcad/cad-data@main/).

To self-host fonts and templates (directory layout, fonts.json, CORS, and baseUrl configuration), see the Self Hosted Fonts and Templates guide in the cad-viewer wiki.

Dimension Creation

import { AcDbAlignedDimension, AcGePoint3d } from '@mlightcad/data-model';

// Create an aligned dimension
const defPoint1 = new AcGePoint3d(0, 0, 0);
const defPoint2 = new AcGePoint3d(10, 0, 0);
const textPosition = new AcGePoint3d(5, 5, 0);

const dimension = new AcDbAlignedDimension(defPoint1, defPoint2, textPosition);
dimension.setDimensionText('10.0');
dimension.setDimensionStyle('Standard');
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Layout Management

import { AcDbLayoutManager } from '@mlightcad/data-model';

// Get layout manager
const layoutManager = database.getLayoutManager();

// Get current layout
const currentLayout = layoutManager.getCurrentLayout();

// Switch to model space
layoutManager.setCurrentLayout('Model');

// Create a new layout
const newLayout = layoutManager.createLayout('MyLayout');
newLayout.setPlotType('Extents');
newLayout.setPlotCentered(true);
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Dependencies

• @mlightcad/common: For common utilities (peer dependency)
• @mlightcad/geometry-engine: For geometric operations (peer dependency)
• @mlightcad/graphic-interface: For graphics interface (peer dependency)
• iconv-lite: For text encoding conversion
• uid: For unique ID generation

DXF reading works out of the box. For DWG, install a converter such as @mlightcad/libredwg-converter. An optional GPL DXF alternative is @mlightcad/dxf-json-converter.

API Documentation

For detailed API documentation, visit the RealDWG-Web documentation.

Contributing

This package is part of the RealDWG-Web monorepo. Please refer to the main project README for contribution guidelines.