gltf-pipeline/lib/getImageExtension.js

Content pipeline tools for optimizing glTF assets.

'use strict';
const Cesium = require('cesium');

const RuntimeError = Cesium.RuntimeError;

module.exports = getImageExtension;

/**
 * Get the image extension from a Buffer containing image data.
 *
 * @param {Buffer} data The image data.
 * @returns {String} The image extension.
 *
 * @private
 */
function getImageExtension(data) {
    const header = data.slice(0, 2);
    const webpHeaderRIFFChars = data.slice(0, 4);
    const webpHeaderWEBPChars = data.slice(8, 12);

    if (header.equals(Buffer.from([0x42, 0x4D]))) {
        return '.bmp';
    } else if (header.equals(Buffer.from([0x47, 0x49]))) {
        return '.gif';
    } else if (header.equals(Buffer.from([0xFF, 0xD8]))) {
        return '.jpg';
    } else if (header.equals(Buffer.from([0x89, 0x50]))) {
        return '.png';
    } else if (header.equals(Buffer.from([0xAB, 0x4B]))) {
        return '.ktx';
    } else if (header.equals(Buffer.from([0x48, 0x78]))) {
        return '.crn';
    } else if (webpHeaderRIFFChars.equals(Buffer.from([0x52, 0x49, 0x46, 0x46])) && webpHeaderWEBPChars.equals(Buffer.from([0x57, 0x45, 0x42, 0x50]))) {
        // See https://developers.google.com/speed/webp/docs/riff_container#webp_file_header
        return '.webp';
    }

    throw new RuntimeError('Image data does not have valid header');
}