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Remove event listeners with signal in web/pdf_viewer.js
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@Snuffleupagus
Snuffleupagus committed May 8, 2024
1 parent b676540 commit bd21cee
Showing 1 changed file with 57 additions and 69 deletions.
126 changes: 57 additions & 69 deletions web/pdf_viewer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -211,12 +211,12 @@ class PDFViewer {

#containerTopLeft = null;

#copyCallbackBound = null;

#enableHighlightFloatingButton = false;

#enablePermissions = false;

#eventAbortController = null;

#mlManager = null;

#getAllTextInProgress = false;
Expand All @@ -231,8 +231,6 @@ class PDFViewer {

#scrollModePageState = null;

#onVisibilityChange = null;

#scaleTimeoutId = null;

#textLayerMode = TextLayerMode.ENABLE;
Expand Down Expand Up @@ -313,7 +311,6 @@ class PDFViewer {

this.scroll = watchScroll(this.container, this._scrollUpdate.bind(this));
this.presentationModeState = PresentationModeState.UNKNOWN;
this._onBeforeDraw = this._onAfterDraw = null;
this._resetView();

if (
Expand Down Expand Up @@ -625,7 +622,7 @@ class PDFViewer {
return params;
}

async #onePageRenderedOrForceFetch() {
async #onePageRenderedOrForceFetch(signal) {
// Unless the viewer *and* its pages are visible, rendering won't start and
// `this._onePageRenderedCapability` thus won't be resolved.
// To ensure that automatic printing, on document load, still works even in
Expand All @@ -646,23 +643,24 @@ class PDFViewer {

// Handle the window/tab becoming inactive *after* rendering has started;
// fixes (another part of) bug 1746213.
const visibilityChangePromise = new Promise(resolve => {
this.#onVisibilityChange = () => {
if (document.visibilityState !== "hidden") {
return;
}
resolve();
};
document.addEventListener("visibilitychange", this.#onVisibilityChange);
const hiddenCapability = Promise.withResolvers();
function onVisibilityChange() {
if (document.visibilityState === "hidden") {
hiddenCapability.resolve();
}
}
document.addEventListener("visibilitychange", onVisibilityChange, {
signal,
});

await Promise.race([
this._onePageRenderedCapability.promise,
visibilityChangePromise,
hiddenCapability.promise,
]);
// Ensure that the "visibilitychange" listener is always removed.
document.removeEventListener("visibilitychange", this.#onVisibilityChange);
this.#onVisibilityChange = null;
// Ensure that the "visibilitychange" listener is removed immediately.
document.removeEventListener("visibilitychange", onVisibilityChange, {
signal,
});
}

async getAllText() {
Expand Down Expand Up @@ -788,26 +786,31 @@ class PDFViewer {
? pdfDocument.getPermissions()
: Promise.resolve();

const { eventBus, pageColors, viewer } = this;

this.#eventAbortController = new AbortController();
const { signal } = this.#eventAbortController;

// Given that browsers don't handle huge amounts of DOM-elements very well,
// enforce usage of PAGE-scrolling when loading *very* long/large documents.
if (pagesCount > PagesCountLimit.FORCE_SCROLL_MODE_PAGE) {
console.warn(
"Forcing PAGE-scrolling for performance reasons, given the length of the document."
);
const mode = (this._scrollMode = ScrollMode.PAGE);
this.eventBus.dispatch("scrollmodechanged", { source: this, mode });
eventBus.dispatch("scrollmodechanged", { source: this, mode });
}

this._pagesCapability.promise.then(
() => {
this.eventBus.dispatch("pagesloaded", { source: this, pagesCount });
eventBus.dispatch("pagesloaded", { source: this, pagesCount });
},
() => {
/* Prevent "Uncaught (in promise)"-messages in the console. */
}
);

this._onBeforeDraw = evt => {
const onBeforeDraw = evt => {
const pageView = this._pages[evt.pageNumber - 1];
if (!pageView) {
return;
Expand All @@ -816,18 +819,17 @@ class PDFViewer {
// evicted from the buffer and destroyed even if we pause its rendering.
this.#buffer.push(pageView);
};
this.eventBus._on("pagerender", this._onBeforeDraw);
eventBus._on("pagerender", onBeforeDraw, { signal });

this._onAfterDraw = evt => {
const onAfterDraw = evt => {
if (evt.cssTransform) {
return;
}
this._onePageRenderedCapability.resolve({ timestamp: evt.timestamp });

this.eventBus._off("pagerendered", this._onAfterDraw);
this._onAfterDraw = null;
eventBus._off("pagerendered", onAfterDraw); // Remove immediately.
};
this.eventBus._on("pagerendered", this._onAfterDraw);
eventBus._on("pagerendered", onAfterDraw, { signal });

// Fetch a single page so we can get a viewport that will be the default
// viewport for all pages
Expand All @@ -846,7 +848,7 @@ class PDFViewer {
const element = (this.#hiddenCopyElement =
document.createElement("div"));
element.id = "hiddenCopyElement";
this.viewer.before(element);
viewer.before(element);
}

if (annotationEditorMode !== AnnotationEditorType.DISABLE) {
Expand All @@ -857,16 +859,16 @@ class PDFViewer {
} else if (isValidAnnotationEditorMode(mode)) {
this.#annotationEditorUIManager = new AnnotationEditorUIManager(
this.container,
this.viewer,
viewer,
this.#altTextManager,
this.eventBus,
eventBus,
pdfDocument,
this.pageColors,
pageColors,
this.#annotationEditorHighlightColors,
this.#enableHighlightFloatingButton,
this.#mlManager
);
this.eventBus.dispatch("annotationeditoruimanager", {
eventBus.dispatch("annotationeditoruimanager", {
source: this,
uiManager: this.#annotationEditorUIManager,
});
Expand All @@ -879,19 +881,19 @@ class PDFViewer {
}

const viewerElement =
this._scrollMode === ScrollMode.PAGE ? null : this.viewer;
this._scrollMode === ScrollMode.PAGE ? null : viewer;
const scale = this.currentScale;
const viewport = firstPdfPage.getViewport({
scale: scale * PixelsPerInch.PDF_TO_CSS_UNITS,
});
// Ensure that the various layers always get the correct initial size,
// see issue 15795.
this.viewer.style.setProperty("--scale-factor", viewport.scale);
viewer.style.setProperty("--scale-factor", viewport.scale);
if (
this.pageColors?.foreground === "CanvasText" ||
this.pageColors?.background === "Canvas"
pageColors?.foreground === "CanvasText" ||
pageColors?.background === "Canvas"
) {
this.viewer.style.setProperty(
viewer.style.setProperty(
"--hcm-highlight-filter",
pdfDocument.filterFactory.addHighlightHCMFilter(
"highlight",
Expand All @@ -901,7 +903,7 @@ class PDFViewer {
"Highlight"
)
);
this.viewer.style.setProperty(
viewer.style.setProperty(
"--hcm-highlight-selected-filter",
pdfDocument.filterFactory.addHighlightHCMFilter(
"highlight_selected",
Expand All @@ -916,7 +918,7 @@ class PDFViewer {
for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
const pageView = new PDFPageView({
container: viewerElement,
eventBus: this.eventBus,
eventBus,
id: pageNum,
scale,
defaultViewport: viewport.clone(),
Expand All @@ -926,7 +928,7 @@ class PDFViewer {
annotationMode,
imageResourcesPath: this.imageResourcesPath,
maxCanvasPixels: this.maxCanvasPixels,
pageColors: this.pageColors,
pageColors,
l10n: this.l10n,
layerProperties: this._layerProperties,
});
Expand All @@ -947,21 +949,24 @@ class PDFViewer {
// Fetch all the pages since the viewport is needed before printing
// starts to create the correct size canvas. Wait until one page is
// rendered so we don't tie up too many resources early on.
this.#onePageRenderedOrForceFetch().then(async () => {
this.#onePageRenderedOrForceFetch(signal).then(async () => {
if (pdfDocument !== this.pdfDocument) {
return; // The document was closed while the first page rendered.
}
this.findController?.setDocument(pdfDocument); // Enable searching.
this._scriptingManager?.setDocument(pdfDocument); // Enable scripting.

if (this.#hiddenCopyElement) {
this.#copyCallbackBound = this.#copyCallback.bind(
this,
textLayerMode
document.addEventListener(
"copy",
this.#copyCallback.bind(this, textLayerMode),
{ signal }
);
document.addEventListener("copy", this.#copyCallbackBound);
}

if (this.#annotationEditorUIManager) {
// Ensure that the Editor buttons, in the toolbar, are updated.
this.eventBus.dispatch("annotationeditormodechanged", {
eventBus.dispatch("annotationeditormodechanged", {
source: this,
mode: this.#annotationEditorMode,
});
Expand Down Expand Up @@ -1011,14 +1016,14 @@ class PDFViewer {
}
});

this.eventBus.dispatch("pagesinit", { source: this });
eventBus.dispatch("pagesinit", { source: this });

pdfDocument.getMetadata().then(({ info }) => {
if (pdfDocument !== this.pdfDocument) {
return; // The document was closed while the metadata resolved.
}
if (info.Language) {
this.viewer.lang = info.Language;
viewer.lang = info.Language;
}
});

Expand Down Expand Up @@ -1079,35 +1084,18 @@ class PDFViewer {
pages: [],
};

if (this._onBeforeDraw) {
this.eventBus._off("pagerender", this._onBeforeDraw);
this._onBeforeDraw = null;
}
if (this._onAfterDraw) {
this.eventBus._off("pagerendered", this._onAfterDraw);
this._onAfterDraw = null;
}
if (this.#onVisibilityChange) {
document.removeEventListener(
"visibilitychange",
this.#onVisibilityChange
);
this.#onVisibilityChange = null;
}
this.#eventAbortController?.abort();
this.#eventAbortController = null;

// Remove the pages from the DOM...
this.viewer.textContent = "";
// ... and reset the Scroll mode CSS class(es) afterwards.
this._updateScrollMode();

this.viewer.removeAttribute("lang");

if (this.#hiddenCopyElement) {
document.removeEventListener("copy", this.#copyCallbackBound);
this.#copyCallbackBound = null;

this.#hiddenCopyElement.remove();
this.#hiddenCopyElement = null;
}
this.#hiddenCopyElement?.remove();
this.#hiddenCopyElement = null;
}

#ensurePageViewVisible() {
Expand Down

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