From fb6c807ba2d5718fb2ca100a738d3df9ca95e402 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 2 Oct 2021 11:24:29 +0200
Subject: [PATCH 1/2] Reduce unnecessary duplication in
`PDFRenderingQueue.getHighestPriority`
---
web/pdf_rendering_queue.js | 24 +++++++++---------------
1 file changed, 9 insertions(+), 15 deletions(-)
diff --git a/web/pdf_rendering_queue.js b/web/pdf_rendering_queue.js
index 7e96c9d2c..1057f3e70 100644
--- a/web/pdf_rendering_queue.js
+++ b/web/pdf_rendering_queue.js
@@ -126,21 +126,15 @@ class PDFRenderingQueue {
}
}
- // 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];
- }
+ // All the visible views have rendered; try to render next/previous page.
+ // (IDs start at 1, so no need to add 1 when `scrolledDown === true`.)
+ const preRenderIndex = scrolledDown
+ ? visible.last.id
+ : visible.first.id - 2;
+ const preRenderView = views[preRenderIndex];
+
+ if (preRenderView && !this.isViewFinished(preRenderView)) {
+ return preRenderView;
}
// Everything that needs to be rendered has been.
return null;
From e4794a678ac27a0fed2296e95f3043356c78ec10 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 2 Oct 2021 11:43:58 +0200
Subject: [PATCH 2/2] Pre-render *one* additional page when spreadModes are
enabled
Please note that we (obviously) don't want to unconditionally pre-render more than one page all the time, since that could very easily lead to overall worse performance in some documents.[1]
However, when spreadModes are enabled it does make sense to attempt to pre-render both of the pages of the next/previous spread.
---
[1] Since it may cause pre-rendering to unnecessarily compete for parsing resources, on the worker-thread, with "regular" rendering.
---
web/base_viewer.js | 8 +++++++-
web/pdf_rendering_queue.js | 17 ++++++++++++-----
2 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/web/base_viewer.js b/web/base_viewer.js
index b1b1086da..54ed21e6e 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -1250,10 +1250,16 @@ class BaseViewer {
const scrollAhead = this._isScrollModeHorizontal
? this.scroll.right
: this.scroll.down;
+ const preRenderExtra =
+ this._scrollMode === ScrollMode.VERTICAL &&
+ this._spreadMode !== SpreadMode.NONE &&
+ !this.isInPresentationMode;
+
const pageView = this.renderingQueue.getHighestPriority(
visiblePages,
this._pages,
- scrollAhead
+ scrollAhead,
+ preRenderExtra
);
if (pageView) {
this._ensurePdfPageLoaded(pageView).then(() => {
diff --git a/web/pdf_rendering_queue.js b/web/pdf_rendering_queue.js
index 1057f3e70..d43d1dd30 100644
--- a/web/pdf_rendering_queue.js
+++ b/web/pdf_rendering_queue.js
@@ -102,8 +102,9 @@ class PDFRenderingQueue {
* @param {Object} visible
* @param {Array} views
* @param {boolean} scrolledDown
+ * @param {boolean} [preRenderExtra]
*/
- getHighestPriority(visible, views, scrolledDown) {
+ getHighestPriority(visible, views, scrolledDown, preRenderExtra = false) {
/**
* The state has changed. Figure out which page has the highest priority to
* render next (if any).
@@ -128,14 +129,20 @@ class PDFRenderingQueue {
// All the visible views have rendered; try to render next/previous page.
// (IDs start at 1, so no need to add 1 when `scrolledDown === true`.)
- const preRenderIndex = scrolledDown
- ? visible.last.id
- : visible.first.id - 2;
- const preRenderView = views[preRenderIndex];
+ let preRenderIndex = scrolledDown ? visible.last.id : visible.first.id - 2;
+ let preRenderView = views[preRenderIndex];
if (preRenderView && !this.isViewFinished(preRenderView)) {
return preRenderView;
}
+ if (preRenderExtra) {
+ preRenderIndex += scrolledDown ? 1 : -1;
+ preRenderView = views[preRenderIndex];
+
+ if (preRenderView && !this.isViewFinished(preRenderView)) {
+ return preRenderView;
+ }
+ }
// Everything that needs to be rendered has been.
return null;
}