@shapediver/sdk.sdtf-v1/src/binary_sdtf/SdtfBinarySdtf.ts

Official sdTF SDK for TypeScript

import { SdtfError } from '@shapediver/sdk.sdtf-core';
import { ISdtfComponentList, toJsonContent } from '../structure/ISdtfComponentList';
import { ISdtfBinarySdtf } from './ISdtfBinarySdtf';

export class SdtfBinarySdtf implements ISdtfBinarySdtf {
    /** Number of bytes of the sdTF header. */
    readonly binaryHeaderLength = 20;

    constructBinarySdtf(componentList: ISdtfComponentList): ArrayBuffer {
        const binaryBody = componentList.binaryBody ?? new ArrayBuffer(0);
        const jsonContent = this.createJsonContent(componentList);
        const header = this.createHeader(jsonContent.byteLength, binaryBody.byteLength);

        // Merge sdTF parts
        return new Uint8Array([
            ...new Uint8Array(header),
            ...new Uint8Array(jsonContent),
            ...new Uint8Array(binaryBody),
        ]).buffer;
    }

    parseBinarySdtf(sdtf: ArrayBuffer): [DataView, DataView] {
        const header = new DataView(sdtf, 0, this.binaryHeaderLength);
        const [contentLength, totalLength] = this.readHeader(header);

        const jsonContent = new DataView(sdtf, this.binaryHeaderLength, contentLength);
        const binaryBody = new DataView(
            sdtf,
            this.binaryHeaderLength + contentLength,
            totalLength - this.binaryHeaderLength - contentLength
        );

        return [jsonContent, binaryBody];
    }

    readHeader(header: DataView | ArrayBuffer): [number, number] {
        if (header instanceof ArrayBuffer) header = new DataView(header);

        const magic =
            String.fromCharCode(header.getUint8(0)) +
            String.fromCharCode(header.getUint8(1)) +
            String.fromCharCode(header.getUint8(2)) +
            String.fromCharCode(header.getUint8(3));
        if (magic !== 'sdtf')
            throw new SdtfError(
                `Invalid identifier: Unknown file type for sdTF identifier '${magic}'.`
            );

        const version = header.getUint32(4, true);
        if (version !== 1)
            throw new SdtfError(`Invalid version: Unsupported sdTF version '${version}'.`);

        const totalLength = header.getUint32(8, true);
        const contentLength = header.getUint32(12, true);

        const contentFormat = header.getUint32(16, true);
        if (contentFormat !== 0)
            throw new SdtfError(
                `Invalid content: Unsupported sdTF content format '${contentFormat}'.`
            );

        return [contentLength, totalLength];
    }

    /** Creates an sdTF header buffer object. */
    createHeader(contentLength: number, bodyLength: number): ArrayBuffer {
        const buffer = new Uint8Array(20);
        const headerDataView = new DataView(buffer.buffer, 0, buffer.byteLength);

        // Write magic (here we must use Unicode encoding)
        const magic = 'sdtf';
        headerDataView.setUint8(0, magic.codePointAt(0)!);
        headerDataView.setUint8(1, magic.codePointAt(1)!);
        headerDataView.setUint8(2, magic.codePointAt(2)!);
        headerDataView.setUint8(3, magic.codePointAt(3)!);

        // Write version
        const version = 1;
        headerDataView.setUint32(4, version, true);

        // Write total length of file
        const totalLength = this.binaryHeaderLength + contentLength + bodyLength;
        headerDataView.setUint32(8, totalLength, true);

        // Write length of content string
        headerDataView.setUint32(12, contentLength, true);

        // Write format string
        const format = 0; // JSON
        headerDataView.setUint32(16, format, true);

        return headerDataView.buffer;
    }

    readJsonContent(jsonContent: DataView | ArrayBuffer): Record<string, unknown> {
        if (jsonContent instanceof ArrayBuffer) jsonContent = new DataView(jsonContent);

        try {
            return JSON.parse(new TextDecoder().decode(jsonContent));
        } catch (e) {
            throw new SdtfError(`Invalid content: Cannot parse sdTF JSON content. ${e.message}`);
        }
    }

    /** Creates an sdTF JSON content buffer object. */
    createJsonContent(componentList: ISdtfComponentList): ArrayBuffer {
        const jsonContent = toJsonContent(componentList);

        try {
            return new TextEncoder().encode(JSON.stringify(jsonContent, undefined, 0));
        } catch (e) {
            throw new SdtfError(`Invalid content: Cannot create sdTF JSON content. ${e.message}`);
        }
    }
}