overleaf/services/web/frontend/js/features/pdf-preview/components/pdf-js-viewer.js

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JavaScript
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import PropTypes from 'prop-types'
import { memo, useCallback, useEffect, useState } from 'react'
import { debounce } from 'lodash'
import PdfViewerControls from './pdf-viewer-controls'
import { useProjectContext } from '../../../shared/context/project-context'
import usePersistedState from '../../../shared/hooks/use-persisted-state'
import { buildHighlightElement } from '../util/highlights'
import PDFJSWrapper from '../util/pdf-js-wrapper'
import withErrorBoundary from '../../../infrastructure/error-boundary'
import ErrorBoundaryFallback from './error-boundary-fallback'
import { useCompileContext } from '../../../shared/context/compile-context'
import getMeta from '../../../utils/meta'
function PdfJsViewer({ url }) {
const { _id: projectId } = useProjectContext()
const {
setError,
firstRenderDone,
highlights,
setPosition,
} = useCompileContext()
const [timePDFFetched, setTimePDFFetched] = useState()
// state values persisted in localStorage to restore on load
const [scale, setScale] = usePersistedState(
`pdf-viewer-scale:${projectId}`,
'page-width'
)
// local state values
const [pdfJsWrapper, setPdfJsWrapper] = useState()
const [initialised, setInitialised] = useState(false)
// create the viewer when the container is mounted
const handleContainer = useCallback(parent => {
if (parent) {
const viewer = new PDFJSWrapper(parent.firstChild)
setPdfJsWrapper(viewer)
return () => viewer.destroy()
}
}, [])
// listen for initialize event
useEffect(() => {
if (pdfJsWrapper) {
const handlePagesinit = () => {
setInitialised(true)
if (getMeta('ol-trackPdfDownload') && firstRenderDone) {
const visible = !document.hidden
if (!visible) {
firstRenderDone({
timePDFFetched,
})
} else {
const timePDFRendered = performance.now()
firstRenderDone({
timePDFFetched,
timePDFRendered,
})
}
}
}
pdfJsWrapper.eventBus.on('pagesinit', handlePagesinit)
return () => pdfJsWrapper.eventBus.off('pagesinit', handlePagesinit)
}
}, [pdfJsWrapper, firstRenderDone, timePDFFetched])
// load the PDF document from the URL
useEffect(() => {
if (pdfJsWrapper && url) {
setTimePDFFetched(performance.now())
setInitialised(false)
setError(undefined)
pdfJsWrapper.loadDocument(url).catch(error => {
console.error(error)
setError('rendering-error')
})
return () => pdfJsWrapper.abortDocumentLoading()
}
}, [pdfJsWrapper, url, setError])
// listen for scroll events
useEffect(() => {
let storePositionTimer
if (initialised && pdfJsWrapper) {
// store the scroll position in localStorage, for the synctex button
const storePosition = debounce(pdfViewer => {
// set position for "sync to code" button
try {
setPosition(pdfViewer.currentPosition)
} catch (error) {
// TODO: investigate handling missing offsetParent in jsdom
// console.error(error)
}
}, 500)
storePositionTimer = window.setTimeout(() => {
storePosition(pdfJsWrapper)
}, 100)
const scrollListener = () => {
storePosition(pdfJsWrapper)
}
pdfJsWrapper.container.addEventListener('scroll', scrollListener)
return () => {
pdfJsWrapper.container.removeEventListener('scroll', scrollListener)
if (storePositionTimer) {
window.clearTimeout(storePositionTimer)
}
storePosition.cancel()
}
}
}, [setPosition, pdfJsWrapper, initialised])
// listen for double-click events
useEffect(() => {
if (pdfJsWrapper) {
const handleTextlayerrendered = textLayer => {
const pageElement = textLayer.source.textLayerDiv.closest('.page')
const doubleClickListener = event => {
window.dispatchEvent(
new CustomEvent('synctex:sync-to-position', {
detail: pdfJsWrapper.clickPosition(event, pageElement, textLayer),
})
)
}
pageElement.addEventListener('dblclick', doubleClickListener)
}
pdfJsWrapper.eventBus.on('textlayerrendered', handleTextlayerrendered)
return () =>
pdfJsWrapper.eventBus.off('textlayerrendered', handleTextlayerrendered)
}
}, [pdfJsWrapper])
// restore the saved scale and scroll position
useEffect(() => {
if (initialised && pdfJsWrapper) {
setScale(scale => {
setPosition(position => {
if (position) {
pdfJsWrapper.scrollToPosition(position, scale)
} else {
pdfJsWrapper.viewer.currentScaleValue = scale
}
return position
})
return scale
})
}
}, [initialised, setScale, setPosition, pdfJsWrapper])
// transmit scale value to the viewer when it changes
useEffect(() => {
if (pdfJsWrapper) {
pdfJsWrapper.viewer.currentScaleValue = scale
}
}, [scale, pdfJsWrapper])
// when highlights are created, build the highlight elements
useEffect(() => {
if (pdfJsWrapper && highlights?.length) {
const elements = []
for (const highlight of highlights) {
try {
const element = buildHighlightElement(highlight, pdfJsWrapper.viewer)
elements.push(element)
} catch (error) {
// ignore invalid highlights
}
}
// scroll to the first highlighted element
elements[0]?.scrollIntoView({
block: 'nearest',
inline: 'start',
behavior: 'smooth',
})
return () => {
for (const element of elements) {
element.remove()
}
}
}
}, [highlights, pdfJsWrapper])
// set the scale in response to zoom option changes
const setZoom = useCallback(
zoom => {
switch (zoom) {
case 'fit-width':
setScale('page-width')
break
case 'fit-height':
setScale('page-height')
break
case 'zoom-in':
setScale(pdfJsWrapper.viewer.currentScale * 1.25)
break
case 'zoom-out':
setScale(pdfJsWrapper.viewer.currentScale * 0.75)
break
}
},
[pdfJsWrapper, setScale]
)
// adjust the scale when the container is resized
useEffect(() => {
if (pdfJsWrapper) {
const resizeListener = () => {
pdfJsWrapper.updateOnResize()
}
const resizeObserver = new ResizeObserver(resizeListener)
resizeObserver.observe(pdfJsWrapper.container)
window.addEventListener('resize', resizeListener)
return () => {
resizeObserver.disconnect()
window.removeEventListener('resize', resizeListener)
}
}
}, [pdfJsWrapper])
const handleKeyDown = useCallback(
event => {
if (!initialised) {
return
}
if ((event.metaKey || event.ctrlKey) && event.key === '=') {
event.preventDefault()
setZoom('zoom-in')
} else if ((event.metaKey || event.ctrlKey) && event.key === '-') {
event.preventDefault()
setZoom('zoom-out')
} else if ((event.metaKey || event.ctrlKey) && event.key === '0') {
event.preventDefault()
setZoom('fit-width')
}
},
[initialised, setZoom]
)
/* eslint-disable jsx-a11y/no-noninteractive-tabindex */
/* eslint-disable jsx-a11y/no-noninteractive-element-interactions */
return (
<div className="pdfjs-viewer pdfjs-viewer-outer" ref={handleContainer}>
<div
className="pdfjs-viewer-inner"
role="tabpanel"
tabIndex="0"
onKeyDown={handleKeyDown}
>
<div className="pdfViewer" />
</div>
<div className="pdfjs-controls">
<PdfViewerControls setZoom={setZoom} />
</div>
</div>
)
}
PdfJsViewer.propTypes = {
url: PropTypes.string.isRequired,
}
export default withErrorBoundary(memo(PdfJsViewer), () => (
<ErrorBoundaryFallback type="pdf" />
))