getuserbarcode/src/input/image_loader.js

An advanced barcode-scanner written in JavaScript

import {findTagsInObjectURL} from './exif_helper';

var ImageLoader = {};
ImageLoader.load = function(directory, callback, offset, size, sequence) {
    var htmlImagesSrcArray = new Array(size),
        htmlImagesArray = new Array(htmlImagesSrcArray.length),
        i,
        img,
        num;

    if (sequence === false) {
        htmlImagesSrcArray[0] = directory;
    } else {
        for ( i = 0; i < htmlImagesSrcArray.length; i++) {
            num = (offset + i);
            htmlImagesSrcArray[i] = directory + "image-" + ("00" + num).slice(-3) + ".jpg";
        }
    }
    htmlImagesArray.notLoaded = [];
    htmlImagesArray.addImage = function(image) {
        htmlImagesArray.notLoaded.push(image);
    };
    htmlImagesArray.loaded = function(loadedImg) {
        var notloadedImgs = htmlImagesArray.notLoaded;
        for (var x = 0; x < notloadedImgs.length; x++) {
            if (notloadedImgs[x] === loadedImg) {
                notloadedImgs.splice(x, 1);
                for (var y = 0; y < htmlImagesSrcArray.length; y++) {
                    var imgName = htmlImagesSrcArray[y].substr(htmlImagesSrcArray[y].lastIndexOf("/"));
                    if (loadedImg.src.lastIndexOf(imgName) !== -1) {
                        htmlImagesArray[y] = {img: loadedImg};
                        break;
                    }
                }
                break;
            }
        }
        if (notloadedImgs.length === 0) {
            if (ENV.development) {
                console.log("Images loaded");
            }
            if (sequence === false) {
                findTagsInObjectURL(directory, ['orientation'])
                    .then(tags => {
                        htmlImagesArray[0].tags = tags;
                        callback(htmlImagesArray);
                    }).catch(e => {
                        console.log(e);
                        callback(htmlImagesArray);
                    });
            } else {
                callback(htmlImagesArray);
            }
        }
    };

    for ( i = 0; i < htmlImagesSrcArray.length; i++) {
        img = new Image();
        htmlImagesArray.addImage(img);
        addOnloadHandler(img, htmlImagesArray);
        img.src = htmlImagesSrcArray[i];
    }
};

function addOnloadHandler(img, htmlImagesArray) {
    img.onload = function() {
        htmlImagesArray.loaded(this);
    };
}

export default (ImageLoader);