@groupsosimple/nativescript-image-generator/lib/explorer.js

Nativescript hook that generates platforms images based on a single high resolution image.

const crypto = require('crypto');
const fs = require('fs');
const path = require('path');
const { promisify } = require('util');
const readdir = promisify(fs.readdir);
async function getImages(appResourcesDirectoryPath) {
    // Find input images
    const appImagesDirectoryPath = getAppImagesDirectoryPath(appResourcesDirectoryPath);
    const imagesPathsList = await getImagesPathsList(appImagesDirectoryPath);
    // Prepare hashes
    const imagesMetadata = await Promise.all(imagesPathsList.map((imagePath) => getMetadataForImagePath(imagePath)));
    // Remove duplicates and keep higher scale
    const filteredImagesMetadata = {};
    imagesMetadata.forEach((metadata) => {
        if (filteredImagesMetadata[metadata.basename] == null || filteredImagesMetadata[metadata.basename].scale < metadata.scale) {
            filteredImagesMetadata[metadata.basename] = metadata;
        }
    });
    return Object.keys(filteredImagesMetadata)
        .sort()
        .map((key) => filteredImagesMetadata[key]);
}
function getAppImagesDirectoryPath(appResourcesDirectoryPath) {
    return path.join(appResourcesDirectoryPath, 'images');
}
async function getImagesPathsList(resourcesPath) {
    try {
        const items = await readdir(resourcesPath, {
            encoding: 'utf8',
            withFileTypes: true,
        });
        return items
            .filter((item) => item.isFile() && path.extname(item.name).toLowerCase() === '.png')
            .map((file) => path.join(resourcesPath, file.name))
            .sort();
    }
    catch (error) {
        if (error.code === 'ENOENT') {
            // No images folder created yet
            fs.mkdir(resourcesPath, { recursive: true }, (error) => {
                if (error)
                    throw new Error(`Unable to create images folder. (${error.message})`);
            });
            return [];
        }
        throw new Error(`Unable to list images in resources. (${error.message})`);
    }
}
async function getMetadataForImagePath(imagePath) {
    return new Promise((resolve, reject) => {
        const imageStream = fs.createReadStream(imagePath);
        const hash = crypto.createHash('md5');
        imageStream.on('data', (data) => {
            hash.update(data, 'utf8');
        });
        imageStream.on('end', () => {
            const basenameWithScale = path.basename(imagePath, '.png');
            const scaleIndex = basenameWithScale.lastIndexOf('@');
            let scale = 1;
            let basename = basenameWithScale;
            if (scaleIndex > 0) {
                const scaleStr = basenameWithScale.substring(scaleIndex + 1, scaleIndex + 2);
                if (['1', '2', '3', '4', '5'].includes(scaleStr)) {
                    scale = parseInt(scaleStr, 10);
                    basename = basenameWithScale.substring(0, scaleIndex);
                }
            }
            resolve({
                filepath: imagePath,
                filename: path.basename(imagePath),
                basename,
                scale,
                hash: hash.digest('hex'),
            });
        });
        imageStream.on('error', (error) => {
            reject(new Error(`Unable to get image data for caching. (${error.message})`));
        });
    });
}
module.exports = {
    getImages,
};