diff --git a/web/base_viewer.js b/web/base_viewer.js
index cd78a11a2..3ea105873 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -54,6 +54,11 @@ import { XfaLayerBuilder } from "./xfa_layer_builder.js";
const DEFAULT_CACHE_SIZE = 10;
+const PagesCountLimit = {
+ FORCE_SCROLL_MODE_PAGE: 15000,
+ FORCE_LAZY_PAGE_INIT: 7500,
+};
+
/**
* @typedef {Object} PDFViewerOptions
* @property {HTMLDivElement} container - The container for the viewer element.
@@ -515,6 +520,16 @@ class BaseViewer {
// Rendering (potentially) depends on this, hence fetching it immediately.
const optionalContentConfigPromise = pdfDocument.getOptionalContentConfig();
+ // 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 });
+ }
+
this._pagesCapability.promise.then(() => {
this.eventBus.dispatch("pagesloaded", {
source: this,
@@ -618,7 +633,10 @@ class BaseViewer {
// In addition to 'disableAutoFetch' being set, also attempt to reduce
// resource usage when loading *very* long/large documents.
- if (pdfDocument.loadingParams.disableAutoFetch || pagesCount > 7500) {
+ if (
+ pdfDocument.loadingParams.disableAutoFetch ||
+ pagesCount > PagesCountLimit.FORCE_LAZY_PAGE_INIT
+ ) {
// XXX: Printing is semi-broken with auto fetch disabled.
this._pagesCapability.resolve();
return;
@@ -1685,6 +1703,9 @@ class BaseViewer {
if (!isValidScrollMode(mode)) {
throw new Error(`Invalid scroll mode: ${mode}`);
}
+ if (this.pagesCount > PagesCountLimit.FORCE_SCROLL_MODE_PAGE) {
+ return; // Disabled for performance reasons.
+ }
this._previousScrollMode = this._scrollMode;
this._scrollMode = mode;
@@ -1957,4 +1978,4 @@ class BaseViewer {
}
}
-export { BaseViewer, PDFPageViewBuffer };
+export { BaseViewer, PagesCountLimit, PDFPageViewBuffer };
diff --git a/web/secondary_toolbar.js b/web/secondary_toolbar.js
index 468dd69c9..3b1f33d44 100644
--- a/web/secondary_toolbar.js
+++ b/web/secondary_toolbar.js
@@ -15,7 +15,7 @@
import { SCROLLBAR_PADDING, ScrollMode, SpreadMode } from "./ui_utils.js";
import { CursorTool } from "./pdf_cursor_tools.js";
-import { PDFSinglePageViewer } from "./pdf_viewer.js";
+import { PagesCountLimit } from "./base_viewer.js";
/**
* @typedef {Object} SecondaryToolbarOptions
@@ -166,22 +166,6 @@ class SecondaryToolbar {
// Bind the event listener for adjusting the 'max-height' of the toolbar.
this.eventBus._on("resize", this._setMaxHeight.bind(this));
-
- // Hide the Scroll/Spread mode buttons, when they're not applicable to the
- // current `BaseViewer` instance (in particular `PDFSinglePageViewer`).
- this.eventBus._on("baseviewerinit", evt => {
- if (evt.source instanceof PDFSinglePageViewer) {
- this.toolbarButtonContainer.classList.add(
- "hiddenScrollModeButtons",
- "hiddenSpreadModeButtons"
- );
- } else {
- this.toolbarButtonContainer.classList.remove(
- "hiddenScrollModeButtons",
- "hiddenSpreadModeButtons"
- );
- }
- });
}
/**
@@ -252,7 +236,7 @@ class SecondaryToolbar {
}
_bindScrollModeListener(buttons) {
- function scrollModeChanged({ mode }) {
+ const scrollModeChanged = ({ mode }) => {
buttons.scrollPageButton.classList.toggle(
"toggled",
mode === ScrollMode.PAGE
@@ -270,13 +254,22 @@ class SecondaryToolbar {
mode === ScrollMode.WRAPPED
);
+ // Permanently *disable* the Scroll buttons when PAGE-scrolling is being
+ // enforced for *very* long/large documents; please see the `BaseViewer`.
+ const forceScrollModePage =
+ this.pagesCount > PagesCountLimit.FORCE_SCROLL_MODE_PAGE;
+ buttons.scrollPageButton.disabled = forceScrollModePage;
+ buttons.scrollVerticalButton.disabled = forceScrollModePage;
+ buttons.scrollHorizontalButton.disabled = forceScrollModePage;
+ buttons.scrollWrappedButton.disabled = forceScrollModePage;
+
// Temporarily *disable* the Spread buttons when horizontal scrolling is
// enabled, since the non-default Spread modes doesn't affect the layout.
const isScrollModeHorizontal = mode === ScrollMode.HORIZONTAL;
buttons.spreadNoneButton.disabled = isScrollModeHorizontal;
buttons.spreadOddButton.disabled = isScrollModeHorizontal;
buttons.spreadEvenButton.disabled = isScrollModeHorizontal;
- }
+ };
this.eventBus._on("scrollmodechanged", scrollModeChanged);
this.eventBus._on("secondarytoolbarreset", evt => {
diff --git a/web/viewer.css b/web/viewer.css
index df33a5054..a8810c528 100644
--- a/web/viewer.css
+++ b/web/viewer.css
@@ -625,11 +625,6 @@ html[dir="rtl"] .secondaryToolbar {
margin-bottom: -4px;
}
-#secondaryToolbarButtonContainer.hiddenScrollModeButtons > .scrollModeButtons,
-#secondaryToolbarButtonContainer.hiddenSpreadModeButtons > .spreadModeButtons {
- display: none !important;
-}
-
.doorHanger,
.doorHangerRight {
border-radius: 2px;
diff --git a/web/viewer.html b/web/viewer.html
index c49aee352..2c22f29ab 100644
--- a/web/viewer.html
+++ b/web/viewer.html
@@ -196,32 +196,32 @@ See https://github.com/adobe-type-tools/cmap-resources
-