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Move handling of the PageOpen/PageClose events into the `PDFScripting…
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…Manager` (PR 13042 follow-up)

By moving this code from the `BaseViewer` and into `PDFScriptingManager`, all of the scripting initialization/handling code is now limited to just one file/class which help overall readability (in my opinion). Also, this patch is a *net reduction* in number of lines of code which can never hurt.

As part of these changes, the intermediary "pageopen"/"pageclose" events are now removed in favor of using the "regular" viewer events directly in `PDFScriptingManager`. Hence this removes some (strictly unnecessary) indirection in the current code, when handling PageOpen/PageClose events, which leads to overall fewer function calls in this part of the code.
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@Snuffleupagus
Snuffleupagus committed Mar 6, 2021
1 parent fb87704 commit 87dd93b
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Showing 2 changed files with 78 additions and 111 deletions.
81 changes: 1 addition & 80 deletions web/base_viewer.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -470,7 +470,7 @@ class BaseViewer {
this.findController.setDocument(null);
}
if (this._scriptingManager) {
// Defer this slightly, to allow the "pageclose" event to be handled.
// Defer this slightly, to allow the "PageClose" event to be handled.
Promise.resolve().then(() => {
this._scriptingManager.setDocument(null);
});
Expand Down Expand Up @@ -670,8 +670,6 @@ class BaseViewer {
this.eventBus._off("pagerendered", this._onAfterDraw);
this._onAfterDraw = null;
}
this._resetScriptingEvents();

// Remove the pages from the DOM...
this.viewer.textContent = "";
// ... and reset the Scroll mode CSS class(es) afterwards.
Expand Down Expand Up @@ -1648,83 +1646,6 @@ class BaseViewer {
this.currentPageNumber = Math.max(currentPageNumber - advance, 1);
return true;
}

async initializeScriptingEvents() {
if (!this.enableScripting || this._pageOpenPendingSet) {
return;
}
const eventBus = this.eventBus,
pageOpenPendingSet = (this._pageOpenPendingSet = new Set()),
scriptingEvents = (this._scriptingEvents = Object.create(null));

const dispatchPageClose = pageNumber => {
if (pageOpenPendingSet.has(pageNumber)) {
return; // No "pageopen" event was dispatched for the previous page.
}
eventBus.dispatch("pageclose", { source: this, pageNumber });
};
const dispatchPageOpen = pageNumber => {
const pageView = this._pages[pageNumber - 1];
if (pageView?.renderingState === RenderingStates.FINISHED) {
pageOpenPendingSet.delete(pageNumber);

eventBus.dispatch("pageopen", {
source: this,
pageNumber,
actionsPromise: pageView.pdfPage?.getJSActions(),
});
} else {
pageOpenPendingSet.add(pageNumber);
}
};

scriptingEvents.onPageChanging = ({ pageNumber, previous }) => {
if (pageNumber === previous) {
return; // The active page didn't change.
}
dispatchPageClose(previous);
dispatchPageOpen(pageNumber);
};
eventBus._on("pagechanging", scriptingEvents.onPageChanging);

scriptingEvents.onPageRendered = ({ pageNumber }) => {
if (!pageOpenPendingSet.has(pageNumber)) {
return; // No pending "pageopen" event for the newly rendered page.
}
if (pageNumber !== this._currentPageNumber) {
return; // The newly rendered page is no longer the current one.
}
dispatchPageOpen(pageNumber);
};
eventBus._on("pagerendered", scriptingEvents.onPageRendered);

scriptingEvents.onPagesDestroy = () => {
dispatchPageClose(this._currentPageNumber);
};
eventBus._on("pagesdestroy", scriptingEvents.onPagesDestroy);

// Ensure that a "pageopen" event is dispatched for the initial page.
dispatchPageOpen(this._currentPageNumber);
}

/**
* @private
*/
_resetScriptingEvents() {
if (!this.enableScripting || !this._pageOpenPendingSet) {
return;
}
const eventBus = this.eventBus,
scriptingEvents = this._scriptingEvents;

// Remove the event listeners.
eventBus._off("pagechanging", scriptingEvents.onPageChanging);
eventBus._off("pagerendered", scriptingEvents.onPageRendered);
eventBus._off("pagesdestroy", scriptingEvents.onPagesDestroy);

this._pageOpenPendingSet = null;
this._scriptingEvents = null;
}
}

export { BaseViewer };
108 changes: 77 additions & 31 deletions web/pdf_scripting_manager.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@

import { createPromiseCapability, shadow } from "pdfjs-lib";
import { apiPageLayoutToSpreadMode } from "./ui_utils.js";
import { RenderingStates } from "./pdf_rendering_queue.js";

/**
* @typedef {Object} PDFScriptingManagerOptions
Expand Down Expand Up @@ -44,6 +45,7 @@ class PDFScriptingManager {

this._scripting = null;
this._mouseState = Object.create(null);
this._pageEventsReady = false;
this._ready = false;

this._eventBus = eventBus;
Expand Down Expand Up @@ -88,6 +90,7 @@ class PDFScriptingManager {

if (!objects && !docActions) {
// No FieldObjects or JavaScript actions were found in the document.
await this._destroyScripting();
return;
}
if (pdfDocument !== this._pdfDocument) {
Expand All @@ -96,17 +99,33 @@ class PDFScriptingManager {
this._scripting = this._createScripting();

this._internalEvents.set("updatefromsandbox", event => {
if (event?.source !== window) {
return;
}
this._updateFromSandbox(event.detail);
});
this._internalEvents.set("dispatcheventinsandbox", event => {
this._scripting?.dispatchEventInSandbox(event.detail);
});

this._internalEvents.set("pageopen", event => {
this._pageOpen(event.pageNumber, event.actionsPromise);
this._internalEvents.set("pagechanging", ({ pageNumber, previous }) => {
if (pageNumber === previous) {
return; // The current page didn't change.
}
this._dispatchPageClose(previous);
this._dispatchPageOpen(pageNumber);
});
this._internalEvents.set("pageclose", event => {
this._pageClose(event.pageNumber);
this._internalEvents.set("pagerendered", ({ pageNumber }) => {
if (!this._pageOpenPending.has(pageNumber)) {
return; // No pending "PageOpen" event for the newly rendered page.
}
if (pageNumber !== this._pdfViewer.currentPageNumber) {
return; // The newly rendered page is no longer the current one.
}
this._dispatchPageOpen(pageNumber);
});
this._internalEvents.set("pagesdestroy", event => {
this._dispatchPageClose(this._pdfViewer.currentPageNumber);
});

this._domEvents.set("mousedown", event => {
Expand Down Expand Up @@ -154,7 +173,10 @@ class PDFScriptingManager {
id: "doc",
name: "Open",
});
await this._pdfViewer.initializeScriptingEvents();
await this._dispatchPageOpen(
this._pdfViewer.currentPageNumber,
/* initialize = */ true
);

// Defer this slightly, to ensure that scripting is *fully* initialized.
Promise.resolve().then(() => {
Expand Down Expand Up @@ -218,6 +240,13 @@ class PDFScriptingManager {
return shadow(this, "_domEvents", new Map());
}

/**
* @private
*/
get _pageOpenPending() {
return shadow(this, "_pageOpenPending", new Set());
}

/**
* @private
*/
Expand Down Expand Up @@ -273,48 +302,63 @@ class PDFScriptingManager {
/**
* @private
*/
async _pageOpen(pageNumber, actionsPromise) {
async _dispatchPageOpen(pageNumber, initialize = false) {
const pdfDocument = this._pdfDocument,
visitedPages = this._visitedPages;

visitedPages.set(
pageNumber,
(async () => {
// Avoid sending, and thus serializing, the `actions` data when the
// *same* page is opened several times.
let actions = null;
if (!visitedPages.has(pageNumber)) {
actions = await actionsPromise;
if (pdfDocument !== this._pdfDocument) {
return; // The document was closed while the actions resolved.
}
}

await this._scripting?.dispatchEventInSandbox({
id: "page",
name: "PageOpen",
pageNumber,
actions,
});
})()
);
if (initialize) {
this._pageEventsReady = true;
}
if (!this._pageEventsReady) {
return; // Scripting isn't fully initialized yet.
}
const pageView = this._pdfViewer.getPageView(/* index = */ pageNumber - 1);

if (pageView?.renderingState !== RenderingStates.FINISHED) {
this._pageOpenPending.add(pageNumber);
return; // Wait for the page to finish rendering.
}
this._pageOpenPending.delete(pageNumber);

const actionsPromise = (async () => {
// Avoid sending, and thus serializing, the `actions` data more than once.
const actions = await (!visitedPages.has(pageNumber)
? pageView.pdfPage?.getJSActions()
: null);
if (pdfDocument !== this._pdfDocument) {
return; // The document was closed while the actions resolved.
}

await this._scripting?.dispatchEventInSandbox({
id: "page",
name: "PageOpen",
pageNumber,
actions,
});
})();
visitedPages.set(pageNumber, actionsPromise);
}

/**
* @private
*/
async _pageClose(pageNumber) {
async _dispatchPageClose(pageNumber) {
const pdfDocument = this._pdfDocument,
visitedPages = this._visitedPages;

if (!this._pageEventsReady) {
return; // Scripting isn't fully initialized yet.
}
if (this._pageOpenPending.has(pageNumber)) {
return; // The page is still rendering; no "PageOpen" event dispatched.
}
const actionsPromise = visitedPages.get(pageNumber);
if (!actionsPromise) {
// Ensure that the "pageclose" event was preceded by a "pageopen" event.
return;
return; // The "PageClose" event must be preceded by a "PageOpen" event.
}
visitedPages.set(pageNumber, null);

// Ensure that the "pageopen" event is handled first.
// Ensure that the "PageOpen" event is dispatched first.
await actionsPromise;
if (pdfDocument !== this._pdfDocument) {
return; // The document was closed while the actions resolved.
Expand Down Expand Up @@ -393,10 +437,12 @@ class PDFScriptingManager {
}
this._domEvents.clear();

this._pageOpenPending.clear();
this._visitedPages.clear();

this._scripting = null;
delete this._mouseState.isDown;
this._pageEventsReady = false;
this._ready = false;

this._destroyCapability?.resolve();
Expand Down

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