dxf-viewer/src/parser/entities/lwpolyline.js

JavaScript DXF file viewer

import * as helpers from "../ParseHelpers.js"

export default function EntityParser() {}

EntityParser.ForEntityName = 'LWPOLYLINE';

EntityParser.prototype.parseEntity = function(scanner, curr) {
    var entity = { type: curr.value, vertices: [] },
        numberOfVertices = 0;
    curr = scanner.next();
    while(curr !== 'EOF') {
        if(curr.code === 0) break;

        switch(curr.code) {
        case 38:
            entity.elevation = curr.value;
            break;
        case 39:
            entity.depth = curr.value;
            break;
        case 70: // 1 = Closed shape, 128 = plinegen?, 0 = default
            entity.shape = ((curr.value & 1) === 1);
            entity.hasContinuousLinetypePattern = ((curr.value & 128) === 128);
            break;
        case 90:
            numberOfVertices = curr.value;
            break;
        case 10: // X coordinate of point
            entity.vertices = parseLWPolylineVertices(numberOfVertices, scanner);
            break;
        case 43:
            if(curr.value !== 0) entity.width = curr.value;
            break;
        case 210:
            entity.extrusionDirection = helpers.parsePoint(scanner);
            break;
        default:
            helpers.checkCommonEntityProperties(entity, curr, scanner);
            break;
        }
        curr = scanner.next();
    }
    return entity;
};

function parseLWPolylineVertices(n, scanner) {
    if(!n || n <= 0) throw Error('n must be greater than 0 vertices');
    var vertices = [], i;
    var vertexIsStarted = false;
    var vertexIsFinished = false;
    var curr = scanner.lastReadGroup;

    for(i = 0; i < n; i++) {
        var vertex = {};
        while(curr !== 'EOF') {
            if(curr.code === 0 || vertexIsFinished) break;

            switch(curr.code) {
            case 10: // X
                if(vertexIsStarted) {
                    vertexIsFinished = true;
                    continue;
                }
                vertex.x = curr.value;
                vertexIsStarted = true;
                break;
            case 20: // Y
                vertex.y = curr.value;
                break;
            case 30: // Z
                vertex.z = curr.value;
                break;
            case 40: // start width
                vertex.startWidth = curr.value;
                break;
            case 41: // end width
                vertex.endWidth = curr.value;
                break;
            case 42: // bulge
                if(curr.value != 0) vertex.bulge = curr.value;
                break;
            case 91: // vertex identifier
                vertex.id = curr.value;
                break;
            default:
                // if we do not hit known code return vertices.  Code might belong to entity
                if (vertexIsStarted) {
                    vertices.push(vertex);
                }
                scanner.rewind();
                return vertices;
            }
            curr = scanner.next();
        }
        // See https://groups.google.com/forum/#!topic/comp.cad.autocad/9gn8s5O_w6E
        vertices.push(vertex);
        vertexIsStarted = false;
        vertexIsFinished = false;
    }
    scanner.rewind();
    return vertices;
};