Enhancement: pngx pdf viewer (#12043)

src-ui/src/app/components/common/pdf-viewer/pdf-viewer.component.ts

@@ -0,0 +1,266 @@
+import {
+  AfterViewInit,
+  Component,
+  ElementRef,
+  EventEmitter,
+  Input,
+  OnChanges,
+  OnDestroy,
+  Output,
+  SimpleChanges,
+  ViewChild,
+} from '@angular/core'
+import {
+  getDocument,
+  GlobalWorkerOptions,
+  PDFDocumentLoadingTask,
+  PDFDocumentProxy,
+} from 'pdfjs-dist/legacy/build/pdf.mjs'
+import {
+  EventBus,
+  PDFFindController,
+  PDFLinkService,
+  PDFSinglePageViewer,
+  PDFViewer,
+} from 'pdfjs-dist/web/pdf_viewer.mjs'
+import {
+  PdfRenderMode,
+  PdfSource,
+  PdfZoomLevel,
+  PdfZoomScale,
+  PngxPdfDocumentProxy,
+} from './pdf-viewer.types'
+
+@Component({
+  selector: 'pngx-pdf-viewer',
+  templateUrl: './pdf-viewer.component.html',
+  styleUrl: './pdf-viewer.component.scss',
+})
+export class PngxPdfViewerComponent
+  implements AfterViewInit, OnChanges, OnDestroy
+{
+  @Input() src!: PdfSource
+  @Input() page?: number
+  @Output() pageChange = new EventEmitter<number>()
+  @Input() rotation?: number
+  @Input() renderMode: PdfRenderMode = PdfRenderMode.All
+  @Input() selectable = true
+  @Input() searchQuery = ''
+  @Input() zoom: PdfZoomLevel = PdfZoomLevel.One
+  @Input() zoomScale: PdfZoomScale = PdfZoomScale.PageWidth
+
+  @Output() afterLoadComplete = new EventEmitter<PngxPdfDocumentProxy>()
+  @Output() rendered = new EventEmitter<void>()
+  @Output() loadError = new EventEmitter<unknown>()
+
+  @ViewChild('container', { static: true })
+  private readonly container!: ElementRef<HTMLDivElement>
+
+  @ViewChild('viewer', { static: true })
+  private readonly viewer!: ElementRef<HTMLDivElement>
+
+  private hasLoaded = false
+  private loadingTask?: PDFDocumentLoadingTask
+  private resizeObserver?: ResizeObserver
+  private pdf?: PDFDocumentProxy
+  private pdfViewer?: PDFViewer | PDFSinglePageViewer
+  private hasRenderedPage = false
+  private lastFindQuery = ''
+  private lastViewerPage?: number
+
+  private readonly eventBus = new EventBus()
+  private readonly linkService = new PDFLinkService({ eventBus: this.eventBus })
+  private readonly findController = new PDFFindController({
+    eventBus: this.eventBus,
+    linkService: this.linkService,
+    updateMatchesCountOnProgress: false,
+  })
+
+  private readonly onPageRendered = () => {
+    this.hasRenderedPage = true
+    this.dispatchFindIfReady()
+    this.rendered.emit()
+  }
+  private readonly onPagesInit = () => this.applyScale()
+  private readonly onPageChanging = (evt: { pageNumber: number }) => {
+    // Avoid [(page)] two-way binding re-triggers navigation
+    this.lastViewerPage = evt.pageNumber
+    this.pageChange.emit(evt.pageNumber)
+  }
+
+  ngOnChanges(changes: SimpleChanges): void {
+    if (changes['src']) {
+      this.hasLoaded = false
+      this.loadDocument()
+      return
+    }
+
+    if (changes['zoomScale']) {
+      this.setupResizeObserver()
+    }
+
+    if (changes['selectable'] || changes['renderMode']) {
+      this.initViewer()
+    }
+
+    if (
+      changes['page'] ||
+      changes['zoom'] ||
+      changes['zoomScale'] ||
+      changes['rotation']
+    ) {
+      this.applyViewerState()
+    }
+
+    if (changes['searchQuery']) {
+      this.dispatchFindIfReady()
+    }
+  }
+
+  ngAfterViewInit(): void {
+    this.setupResizeObserver()
+    this.initViewer()
+    if (!this.hasLoaded) {
+      this.loadDocument()
+      return
+    }
+    if (this.pdf) {
+      this.applyViewerState()
+    }
+  }
+
+  ngOnDestroy(): void {
+    this.eventBus.off('pagerendered', this.onPageRendered)
+    this.eventBus.off('pagesinit', this.onPagesInit)
+    this.eventBus.off('pagechanging', this.onPageChanging)
+    this.resizeObserver?.disconnect()
+    this.loadingTask?.destroy()
+    this.pdfViewer?.cleanup()
+    this.pdfViewer = undefined
+  }
+
+  private async loadDocument(): Promise<void> {
+    if (this.hasLoaded) {
+      return
+    }
+
+    this.hasLoaded = true
+    this.hasRenderedPage = false
+    this.lastFindQuery = ''
+    this.loadingTask?.destroy()
+
+    GlobalWorkerOptions.workerSrc = '/assets/js/pdf.worker.min.mjs'
+    this.loadingTask = getDocument(this.src)
+
+    try {
+      const pdf = await this.loadingTask.promise
+      this.pdf = pdf
+      this.linkService.setDocument(pdf)
+      this.findController.onIsPageVisible = () => true
+      this.pdfViewer?.setDocument(pdf)
+      this.applyViewerState()
+      this.afterLoadComplete.emit(pdf)
+    } catch (err) {
+      this.loadError.emit(err)
+    }
+  }
+
+  private setupResizeObserver(): void {
+    this.resizeObserver?.disconnect()
+    this.resizeObserver = new ResizeObserver(() => {
+      this.applyScale()
+    })
+    this.resizeObserver.observe(this.container.nativeElement)
+  }
+
+  private initViewer(): void {
+    this.viewer.nativeElement.innerHTML = ''
+    this.pdfViewer?.cleanup()
+    this.hasRenderedPage = false
+    this.lastFindQuery = ''
+
+    const textLayerMode = this.selectable === false ? 0 : 1
+    const options = {
+      container: this.container.nativeElement,
+      viewer: this.viewer.nativeElement,
+      eventBus: this.eventBus,
+      linkService: this.linkService,
+      findController: this.findController,
+      textLayerMode,
+      removePageBorders: true,
+    }
+
+    this.pdfViewer =
+      this.renderMode === PdfRenderMode.Single
+        ? new PDFSinglePageViewer(options)
+        : new PDFViewer(options)
+    this.linkService.setViewer(this.pdfViewer)
+
+    this.eventBus.off('pagerendered', this.onPageRendered)
+    this.eventBus.off('pagesinit', this.onPagesInit)
+    this.eventBus.off('pagechanging', this.onPageChanging)
+    this.eventBus.on('pagerendered', this.onPageRendered)
+    this.eventBus.on('pagesinit', this.onPagesInit)
+    this.eventBus.on('pagechanging', this.onPageChanging)
+
+    if (this.pdf) {
+      this.pdfViewer.setDocument(this.pdf)
+      this.applyViewerState()
+    }
+  }
+
+  private applyViewerState(): void {
+    if (!this.pdfViewer) {
+      return
+    }
+    const hasPages = this.pdfViewer.pagesCount > 0
+    if (typeof this.rotation === 'number' && hasPages) {
+      this.pdfViewer.pagesRotation = this.rotation
+    }
+    if (
+      typeof this.page === 'number' &&
+      hasPages &&
+      this.page !== this.lastViewerPage
+    ) {
+      this.pdfViewer.currentPageNumber = this.page
+    }
+    if (this.page === this.lastViewerPage) {
+      this.lastViewerPage = undefined
+    }
+    if (hasPages) {
+      this.applyScale()
+    }
+    this.dispatchFindIfReady()
+  }
+
+  private applyScale(): void {
+    if (!this.pdfViewer) {
+      return
+    }
+    if (this.pdfViewer.pagesCount === 0) {
+      return
+    }
+    const zoomFactor = Number(this.zoom) || 1
+    this.pdfViewer.currentScaleValue = this.zoomScale
+    if (zoomFactor !== 1) {
+      this.pdfViewer.currentScale = this.pdfViewer.currentScale * zoomFactor
+    }
+  }
+
+  private dispatchFindIfReady(): void {
+    if (!this.hasRenderedPage) {
+      return
+    }
+    const query = this.searchQuery.trim()
+    if (query === this.lastFindQuery) {
+      return
+    }
+    this.lastFindQuery = query
+    this.eventBus.dispatch('find', {
+      query,
+      caseSensitive: false,
+      highlightAll: query.length > 0,
+      phraseSearch: true,
+    })
+  }
+}