/* Copyright 2012 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
const CLEANUP_TIMEOUT = 30000
const RenderingStates = {
INITIAL: 0,
RUNNING: 1,
PAUSED: 2,
FINISHED: 3,
}
/**
* Controls rendering of the views for pages and thumbnails.
*/
class PDFRenderingQueue {
constructor() {
this.pdfViewer = null
this.pdfThumbnailViewer = null
this.onIdle = null
this.highestPriorityPage = null
this.idleTimeout = null
this.printing = false
this.isThumbnailViewEnabled = false
}
/**
* @param {PDFViewer} pdfViewer
*/
setViewer(pdfViewer) {
this.pdfViewer = pdfViewer
}
/**
* @param {PDFThumbnailViewer} pdfThumbnailViewer
*/
setThumbnailViewer(pdfThumbnailViewer) {
this.pdfThumbnailViewer = pdfThumbnailViewer
}
/**
* @param {IRenderableView} view
* @returns {boolean}
*/
isHighestPriority(view) {
return this.highestPriorityPage === view.renderingId
}
/**
* @param {Object} currentlyVisiblePages
*/
renderHighestPriority(currentlyVisiblePages) {
if (this.idleTimeout) {
clearTimeout(this.idleTimeout)
this.idleTimeout = null
}
// Pages have a higher priority than thumbnails, so check them first.
if (this.pdfViewer.forceRendering(currentlyVisiblePages)) {
return
}
// No pages needed rendering, so check thumbnails.
if (this.pdfThumbnailViewer && this.isThumbnailViewEnabled) {
if (this.pdfThumbnailViewer.forceRendering()) {
return
}
}
if (this.printing) {
// If printing is currently ongoing do not reschedule cleanup.
return
}
if (this.onIdle) {
this.idleTimeout = setTimeout(this.onIdle.bind(this), CLEANUP_TIMEOUT)
}
}
/**
* @param {Object} visible
* @param {Array} views
* @param {boolean} scrolledDown
*/
getHighestPriority(visible, views, scrolledDown) {
/**
* The state has changed. Figure out which page has the highest priority to
* render next (if any).
*
* Priority:
* 1. visible pages
* 2. if last scrolled down, the page after the visible pages, or
* if last scrolled up, the page before the visible pages
*/
const visibleViews = visible.views
const numVisible = visibleViews.length
if (numVisible === 0) {
return null
}
for (let i = 0; i < numVisible; ++i) {
const view = visibleViews[i].view
if (!this.isViewFinished(view)) {
return view
}
}
// All the visible views have rendered; try to render next/previous pages.
if (scrolledDown) {
const nextPageIndex = visible.last.id
// IDs start at 1, so no need to add 1.
if (views[nextPageIndex] && !this.isViewFinished(views[nextPageIndex])) {
return views[nextPageIndex]
}
} else {
const previousPageIndex = visible.first.id - 2
if (
views[previousPageIndex] &&
!this.isViewFinished(views[previousPageIndex])
) {
return views[previousPageIndex]
}
}
// Everything that needs to be rendered has been.
return null
}
/**
* @param {IRenderableView} view
* @returns {boolean}
*/
isViewFinished(view) {
return view.renderingState === RenderingStates.FINISHED
}
/**
* Render a page or thumbnail view. This calls the appropriate function
* based on the views state. If the view is already rendered it will return
* `false`.
*
* @param {IRenderableView} view
*/
renderView(view) {
switch (view.renderingState) {
case RenderingStates.FINISHED:
return false
case RenderingStates.PAUSED:
this.highestPriorityPage = view.renderingId
view.resume()
break
case RenderingStates.RUNNING:
this.highestPriorityPage = view.renderingId
break
case RenderingStates.INITIAL:
this.highestPriorityPage = view.renderingId
view
.draw()
.finally(() => {
this.renderHighestPriority()
})
.catch((reason) => {
console.error(`renderView: "${reason}"`)
})
break
}
return true
}
}
export { RenderingStates, PDFRenderingQueue }