46 lines
930 B
JavaScript
46 lines
930 B
JavaScript
let EventEmitter = require('events').EventEmitter
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let LoadIndicator = require('./view/load-indicator')
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module.exports = class ComicBook extends EventEmitter {
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constructor (srcs = []) {
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super()
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// requested image srcs
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this.srcs = new Set(srcs)
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// loaded image objects
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this.pages = new Map()
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this.loadIndicator = new LoadIndicator()
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this.addEventListeners()
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}
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addEventListeners () {
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this.on('preload:start', this.loadIndicator.show.bind(this.loadIndicator))
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}
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preload () {
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this.emit('preload:start')
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this.srcs.forEach(loadImage.bind(this))
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}
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}
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function loadImage (src, pageIndex) {
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let self = this
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let image = new window.Image()
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image.src = src
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image.onload = setImage
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function setImage () {
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self.pages.set(pageIndex, this)
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self.emit('preload:image', this)
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if (self.pages.size === self.srcs.size) {
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self.emit('preload:finish')
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}
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}
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}
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