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Document Model

About 4 min

Document Model

CadDocument represents a CAD document and is the container for all drawing data. It manages all document-level data including layers, blocks, styles, and more.

Overview

Document Basic Information

import { Engine, CadDocument } from 'vjcad';

// Get current document
const doc: CadDocument = Engine.currentDoc;

// Basic properties
console.log('Document name:', doc.name);           // File name
console.log('Document path:', doc.path);           // Full path
console.log('Document ID:', doc.docId);            // Unique identifier
console.log('Modified:', doc.DBMOD === 1);  // Modification status

// Quick access via Engine
console.log('Drawing name:', Engine.DWGNAME);     // Same as doc.name
console.log('Drawing prefix:', Engine.DWGPREFIX);   // Same as doc.path
console.log('Named drawing:', Engine.DWGTITLED); // path !== ""

Document Properties

PropertyTypeDescription
namestringDocument name (file name)
pathstringDocument full path
docIdnumberDocument unique identifier
DBMODnumberModification status (0=unmodified, 1=modified)
CLAYERstringCurrent layer name
LTSCALEnumberGlobal line type scale
DIMSCALEnumberDimension global scale
TEXTSIZEnumberDefault text height

Document Environment Variables

import { Engine, CadDocument } from 'vjcad';

const doc = Engine.currentDoc;

// Layer related
doc.CLAYER = 'Dimension';              // Set current layer
console.log('Current layer:', doc.CLAYER);

// Can also use setCLAYER method
doc.setCLAYER('Layer1', true);       // Second parameter indicates whether to update UI

// Line type scale
doc.LTSCALE = 100;                  // Global line type scale
console.log('Global line type scale:', doc.LTSCALE);

// Dimension scale
doc.DIMSCALE = 50;                  // Dimension global scale
console.log('Dimension scale:', doc.DIMSCALE);

// Text height
doc.TEXTSIZE = 2.5;                 // Default text height

Layer Collection (Layers)

The layer collection manages all layers in the document.

Accessing Layers

import { Engine, Layer } from 'vjcad';

const doc = Engine.currentDoc;
const layers = doc.layers;

// Get all layers
console.log('Layer count:', layers.items.length);

// Iterate layers
for (const layer of layers.items) {
  console.log(`Layer: ${layer.name}, Color: ${layer.color}, On: ${layer.layerOn}`);
}

// Get layer by name
const layer0 = layers.itemByName('0');
console.log('Layer 0 color:', layer0?.color);

// Get layer by index
const firstLayer = layers.itemByIndex(0);

Creating Layers

import { Engine } from 'vjcad';

const layers = Engine.currentDoc.layers;

// Method 1: Auto naming
const newLayer1 = layers.makeLayer();
console.log('New layer name:', newLayer1.name);  // "Layer1", "Layer2", ...

// Method 2: Specify name
const newLayer2 = layers.addlayer('Dimension', true, 3);  // Name, on, color
newLayer2.lineType = 'CONTINUOUS';

// Method 3: Check and create
if (!layers.has('MyLayer')) {
  const myLayer = layers.addlayer('MyLayer', true, 1);
}

Layer Properties

import { Engine, Layer } from 'vjcad';

const layer = Engine.currentDoc.layers.itemByName('Layer1');
if (layer) {
  // Basic properties
  layer.name = 'NewName';          // Layer name
  layer.color = 1;                // Layer color (1=red)
  layer.lineType = 'HIDDEN';      // Layer line type
  layer.lineWeight = 0.25;        // Layer line weight (mm)
  
  // State control
  layer.layerOn = true;           // Layer on/off (true=visible)
  layer.frozen = false;           // Frozen state (true=frozen)
  layer.locked = false;           // Locked state (true=locked)
  layer.plottable = true;         // Plottable (true=plottable)
  
  // Transparency
  layer.transparency = 0;         // Transparency (0-100)
}

Layer Operations

import { Engine } from 'vjcad';

const layers = Engine.currentDoc.layers;

// Delete layer
const layerToDelete = layers.itemByName('TempLayer');
if (layerToDelete && layerToDelete.name !== '0') {
  layers.delete(layerToDelete);
}

// Check if layer exists
const exists = layers.has('Dimension');

// Get layer index
const index = layers.indexOf('Layer1');

Block Collection (Blocks)

The block collection manages all block definitions, including model space and paper space.

Accessing Blocks

import { Engine, BlockDefinition } from 'vjcad';

const doc = Engine.currentDoc;
const blocks = doc.blocks;

// Get model space
const modelSpace = blocks.itemByName('*Model');
console.log('Model space entity count:', modelSpace?.items.length);

// Get paper space
const paperSpace = blocks.itemByName('*Paper');

// Get current space
const currentSpace: BlockDefinition = doc.currentSpace;

// Iterate all block definitions
for (const block of blocks.items) {
  if (!block.name.startsWith('*')) {  // Exclude system blocks
    console.log(`Block: ${block.name}, Entity count: ${block.items.length}`);
  }
}

Creating Blocks

import { Engine, BlockDefinition, LineEnt, CircleEnt, Point2D } from 'vjcad';

const blocks = Engine.currentDoc.blocks;

// Create new block definition
const newBlock = new BlockDefinition();
newBlock.name = 'MyBlock';
newBlock.origin = new Point2D(0, 0);  // Block base point

// Add entities to block
const line = new LineEnt(new Point2D(0, 0), new Point2D(100, 0));
const circle = new CircleEnt(new Point2D(50, 50), 20);
newBlock.add(line);
newBlock.add(circle);

// Add to block collection
blocks.add(newBlock);

Block Properties

import { BlockDefinition, Point2D } from 'vjcad';

const block: BlockDefinition = /* ... */;

// Basic properties
block.name = 'BlockName';            // Block name
block.origin = new Point2D(0, 0); // Block base point

// Entity operations
const entities = block.items;      // Get all entities
block.add(entity);                 // Add entity
block.erase([entity]);             // Delete entity

// Space properties
const zoom = block.zoom;           // Current zoom level
const center = block.viewCenter;   // View center

Current Space

The current space is the space the user is editing (model space or paper space of a layout).

import { Engine, BlockDefinition, EntityBase } from 'vjcad';

// Get current space
const currentSpace: BlockDefinition = Engine.currentSpace;
// Same as Engine.currentDoc.currentSpace

// Access entities in space
const entities: EntityBase[] = currentSpace.items;
console.log('Current space entity count:', entities.length);

// Iterate entities
for (const entity of entities) {
  console.log(`${entity.type}: ${entity.id}, Layer: ${entity.layer}`);
}

// Space view properties
console.log('Zoom level:', currentSpace.zoom);
console.log('View center:', currentSpace.viewCenter);

Other Data Collections

Text Styles

import { Engine } from 'vjcad';

const textStyles = Engine.currentDoc.textStyles;

// Iterate text styles
for (const style of textStyles.items) {
  console.log(`Style: ${style.name}, Font: ${style.fontName}`);
}

// Get style
const standard = textStyles.itemByName('Standard');

Dimension Styles

import { Engine } from 'vjcad';

const dimStyles = Engine.currentDoc.dimensionStyles;

// Iterate dimension styles
for (const style of dimStyles.items) {
  console.log(`Style: ${style.name}`);
}

Image Collection

import { Engine } from 'vjcad';

const images = Engine.currentDoc.images;

// Iterate images
for (const image of images.items) {
  console.log(`Image: ${image.name}, Path: ${image.path}`);
}

Document Serialization

Export to JSON

import { Engine, CadDocument } from 'vjcad';

const doc = Engine.currentDoc;

// Export to database format object
const dbDoc = doc.toDb();

// Convert to JSON string
const jsonStr = JSON.stringify(dbDoc);

// Save to file (example)
// await saveToFile('drawing.json', jsonStr);

Import from JSON

import { CadDocument } from 'vjcad';

// Restore from JSON
const jsonStr = /* Read file content */;
const dbData = JSON.parse(jsonStr);

const newDoc = new CadDocument();
await newDoc.fromDb(dbData);

// Set as current document
Engine.setActiveDocument(newDoc);

Document Lifecycle

Document Operations

import { Engine, CadDocument } from 'vjcad';

// Create new document
const newDoc = new CadDocument();
newDoc.name = 'NewDrawing';

// Add to document collection
Engine.docs.items.push(newDoc);

// Set as active document
Engine.setActiveDocument(newDoc);

// Clean up resources when closing document
Engine.disposeDocument(newDoc);

Multi-Document Management

import { Engine, CadDocument } from 'vjcad';

// Get all open documents
const docs = Engine.docs.items;
console.log('Open document count:', docs.length);

// Iterate documents
for (const doc of docs) {
  console.log(`${doc.name} - ${doc.DBMOD === 1 ? 'Modified' : 'Unmodified'}`);
}

// Switch document
const targetDoc = docs.find(d => d.name === 'DrawingA');
if (targetDoc) {
  Engine.setActiveDocument(targetDoc);
}

Document Collection Summary

CollectionTypeDescription
layersLayersLayer collection, manages all layers
blocksBlocksBlock definition collection, includes model space and paper space
layoutsLayoutsLayout collection, manages print layouts
imagesImagesImage collection, external image references
textStylesTextStylesText style collection
dimensionStylesDimStylesDimension style collection
lineTypesLineTypesLine type definition collection
plotStylesPlotStylesPlot style collection

Next Steps