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Merge pull request #20462 from calixteman/improve_thumbnails

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Slightly reduce the memory used by thumbnails
This commit is contained in:
Tim van der Meij 2025-11-29 15:36:46 +01:00 committed by GitHub
commit f44e5f0e63
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GPG Key ID: B5690EEEBB952194
4 changed files with 102 additions and 114 deletions
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4
test/integration/thumbnail_view_spec.mjs
View File

@ -21,13 +21,13 @@ describe("PDF Thumbnail View", () => {
await page.waitForSelector(thumbSelector, { visible: true });
await page.waitForSelector(
'#thumbnailView .thumbnail[data-loaded="true"]'
"#thumbnailView .thumbnail:not(.missingThumbnailImage)"
);
const src = await page.$eval(thumbSelector, el => el.src);
expect(src)
.withContext(`In ${browserName}`)
.toMatch(/^data:image\//);
.toMatch(/^blob:http:/);
})
);
});

113
web/pdf_thumbnail_view.js
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@ -23,7 +23,11 @@
// eslint-disable-next-line max-len
/** @typedef {import("./pdf_rendering_queue").PDFRenderingQueue} PDFRenderingQueue */
import { OutputScale, RenderingCancelledException } from "pdfjs-lib";
import {
FeatureTest,
OutputScale,
RenderingCancelledException,
} from "pdfjs-lib";
import { AppOptions } from "./app_options.js";
import { RenderingStates } from "./ui_utils.js";
@ -31,13 +35,6 @@ const DRAW_UPSCALE_FACTOR = 2; // See comment in `PDFThumbnailView.draw` below.
const MAX_NUM_SCALING_STEPS = 3;
const THUMBNAIL_WIDTH = 98; // px
function zeroCanvas(c) {
// Zeroing the width and height causes Firefox to release graphics
// resources immediately, which can greatly reduce memory consumption.
c.width = 0;
c.height = 0;
}
/**
* @typedef {Object} PDFThumbnailViewOptions
* @property {HTMLDivElement} container - The viewer element.
@ -61,12 +58,15 @@ function zeroCanvas(c) {
*/
class TempImageFactory {
static #tempCanvas = null;
static getCanvas(width, height) {
const tempCanvas = (this.#tempCanvas ||= document.createElement("canvas"));
let tempCanvas;
if (FeatureTest.isOffscreenCanvasSupported) {
tempCanvas = new OffscreenCanvas(width, height);
} else {
tempCanvas = document.createElement("canvas");
tempCanvas.width = width;
tempCanvas.height = height;
}
// Since this is a temporary canvas, we need to fill it with a white
// background ourselves. `#getPageDrawContext` uses CSS rules for this.
@ -75,14 +75,7 @@ class TempImageFactory {
ctx.fillStyle = "rgb(255, 255, 255)";
ctx.fillRect(0, 0, width, height);
ctx.restore();
return [tempCanvas, tempCanvas.getContext("2d")];
}
static destroyCanvas() {
if (this.#tempCanvas) {
zeroCanvas(this.#tempCanvas);
}
this.#tempCanvas = null;
return [tempCanvas, ctx];
}
}
@ -126,27 +119,24 @@ class PDFThumbnailView {
this.renderingState = RenderingStates.INITIAL;
this.resume = null;
const anchor = document.createElement("a");
anchor.href = linkService.getAnchorUrl("#page=" + id);
const anchor = (this.anchor = document.createElement("a"));
anchor.href = linkService.getAnchorUrl(`#page=${id}`);
anchor.setAttribute("data-l10n-id", "pdfjs-thumb-page-title");
anchor.setAttribute("data-l10n-args", this.#pageL10nArgs);
anchor.onclick = function () {
anchor.onclick = () => {
linkService.goToPage(id);
return false;
};
this.anchor = anchor;
const div = document.createElement("div");
div.className = "thumbnail";
const div = (this.div = document.createElement("div"));
div.classList.add("thumbnail", "missingThumbnailImage");
div.setAttribute("data-page-number", this.id);
this.div = div;
this.#updateDims();
const img = document.createElement("div");
img.className = "thumbnailImage";
this._placeholderImg = img;
const image = (this.image = document.createElement("img"));
image.className = "thumbnailImage";
div.append(img);
div.append(image);
anchor.append(div);
container.append(anchor);
}
@ -155,13 +145,11 @@ class PDFThumbnailView {
const { width, height } = this.viewport;
const ratio = width / height;
this.canvasWidth = THUMBNAIL_WIDTH;
this.canvasHeight = (this.canvasWidth / ratio) | 0;
this.scale = this.canvasWidth / width;
const canvasWidth = (this.canvasWidth = THUMBNAIL_WIDTH);
const canvasHeight = (this.canvasHeight = (canvasWidth / ratio) | 0);
this.scale = canvasWidth / width;
const { style } = this.div;
style.setProperty("--thumbnail-width", `${this.canvasWidth}px`);
style.setProperty("--thumbnail-height", `${this.canvasHeight}px`);
this.div.style.height = `${canvasHeight}px`;
}
setPdfPage(pdfPage) {
@ -175,14 +163,16 @@ class PDFThumbnailView {
reset() {
this.cancelRendering();
this.renderingState = RenderingStates.INITIAL;
this.div.removeAttribute("data-loaded");
this.image?.replaceWith(this._placeholderImg);
this.#updateDims();
if (this.image) {
this.image.removeAttribute("src");
delete this.image;
const { image } = this;
const url = image.src;
if (url) {
URL.revokeObjectURL(url);
image.removeAttribute("data-l10n-id");
image.removeAttribute("data-l10n-args");
image.src = "";
this.div.classList.add("missingThumbnailImage");
}
}
@ -213,7 +203,6 @@ class PDFThumbnailView {
#getPageDrawContext(upscaleFactor = 1) {
// Keep the no-thumbnail outline visible, i.e. `data-loaded === false`,
// until rendering/image conversion is complete, to avoid display issues.
const canvas = document.createElement("canvas");
const outputScale = new OutputScale();
const width = upscaleFactor * this.canvasWidth,
height = upscaleFactor * this.canvasHeight;
@ -224,6 +213,9 @@ class PDFThumbnailView {
this.maxCanvasPixels,
this.maxCanvasDim
);
// Because of: https://bugzilla.mozilla.org/show_bug.cgi?id=2003060
// we need use a HTMLCanvasElement here.
const canvas = document.createElement("canvas");
canvas.width = (width * outputScale.sx) | 0;
canvas.height = (height * outputScale.sy) | 0;
@ -234,23 +226,23 @@ class PDFThumbnailView {
return { canvas, transform };
}
#convertCanvasToImage(canvas) {
async #convertCanvasToImage(canvas) {
if (this.renderingState !== RenderingStates.FINISHED) {
throw new Error("#convertCanvasToImage: Rendering has not finished.");
}
const reducedCanvas = this.#reduceImage(canvas);
const image = document.createElement("img");
image.className = "thumbnailImage";
const { image } = this;
const { promise, resolve } = Promise.withResolvers();
reducedCanvas.toBlob(resolve);
const blob = await promise;
image.src = URL.createObjectURL(blob);
image.setAttribute("data-l10n-id", "pdfjs-thumb-page-canvas");
image.setAttribute("data-l10n-args", this.#pageL10nArgs);
image.src = reducedCanvas.toDataURL();
this.image = image;
this.div.setAttribute("data-loaded", true);
this._placeholderImg.replaceWith(image);
zeroCanvas(reducedCanvas);
this.div.classList.remove("missingThumbnailImage");
if (!FeatureTest.isOffscreenCanvasSupported) {
// Clean up the canvas element since it is no longer needed.
reducedCanvas.width = reducedCanvas.height = 0;
}
}
async draw() {
@ -303,7 +295,6 @@ class PDFThumbnailView {
await renderTask.promise;
} catch (e) {
if (e instanceof RenderingCancelledException) {
zeroCanvas(canvas);
return;
}
error = e;
@ -317,8 +308,7 @@ class PDFThumbnailView {
}
this.renderingState = RenderingStates.FINISHED;
this.#convertCanvasToImage(canvas);
zeroCanvas(canvas);
await this.#convertCanvasToImage(canvas);
this.eventBus.dispatch("thumbnailrendered", {
source: this,
@ -449,14 +439,9 @@ class PDFThumbnailView {
*/
setPageLabel(label) {
this.pageLabel = typeof label === "string" ? label : null;
this.anchor.setAttribute("data-l10n-args", this.#pageL10nArgs);
if (this.renderingState !== RenderingStates.FINISHED) {
return;
}
this.image?.setAttribute("data-l10n-args", this.#pageL10nArgs);
this.image.setAttribute("data-l10n-args", this.#pageL10nArgs);
}
}
export { PDFThumbnailView, TempImageFactory };
export { PDFThumbnailView };

7
web/pdf_thumbnail_viewer.js
View File

@ -27,7 +27,7 @@ import {
scrollIntoView,
watchScroll,
} from "./ui_utils.js";
import { PDFThumbnailView, TempImageFactory } from "./pdf_thumbnail_view.js";
import { PDFThumbnailView } from "./pdf_thumbnail_view.js";
const THUMBNAIL_SCROLL_MARGIN = -19;
const THUMBNAIL_SELECTED_CLASS = "selected";
@ -174,7 +174,6 @@ class PDFThumbnailViewer {
thumbnail.reset();
}
}
TempImageFactory.destroyCanvas();
}
#resetView() {
@ -209,10 +208,11 @@ class PDFThumbnailViewer {
.then(firstPdfPage => {
const pagesCount = pdfDocument.numPages;
const viewport = firstPdfPage.getViewport({ scale: 1 });
const fragment = document.createDocumentFragment();
for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
const thumbnail = new PDFThumbnailView({
container: this.container,
container: fragment,
eventBus: this.eventBus,
id: pageNum,
defaultViewport: viewport.clone(),
@ -234,6 +234,7 @@ class PDFThumbnailViewer {
// Ensure that the current thumbnail is always highlighted on load.
const thumbnailView = this._thumbnails[this._currentPageNumber - 1];
thumbnailView.div.classList.add(THUMBNAIL_SELECTED_CLASS);
this.container.append(fragment);
})
.catch(reason => {
console.error("Unable to initialize thumbnail viewer", reason);

82
web/viewer.css
View File

@ -717,61 +717,63 @@ body {
}
#thumbnailView {
--thumbnail-width: 98px;
display: flex;
flex-wrap: wrap;
width: calc(100% - 60px);
padding: 10px 30px 0;
}
#thumbnailView > a:is(:active, :focus) {
outline: 0;
}
> a {
width: auto;
height: auto;
.thumbnail {
/* Define these variables here, and not in :root, since the individual
thumbnails may have different sizes. */
--thumbnail-width: 0;
--thumbnail-height: 0;
float: var(--inline-start);
> .thumbnail {
width: var(--thumbnail-width);
height: var(--thumbnail-height);
margin: 0 10px 5px;
padding: 1px;
border: 7px solid transparent;
border-radius: 2px;
}
#thumbnailView > a:last-of-type > .thumbnail {
margin-bottom: 10px;
}
a:focus > .thumbnail,
.thumbnail:hover {
border-color: var(--thumbnail-hover-color);
}
.thumbnail.selected {
&.selected {
border-color: var(--thumbnail-selected-color) !important;
}
.thumbnailImage {
width: var(--thumbnail-width);
height: var(--thumbnail-height);
opacity: 0.9;
}
a:focus > .thumbnail > .thumbnailImage,
.thumbnail:hover > .thumbnailImage {
opacity: 0.95;
}
.thumbnail.selected > .thumbnailImage {
> .thumbnailImage {
opacity: 1 !important;
}
}
}
.thumbnail:not([data-loaded]) > .thumbnailImage {
width: calc(var(--thumbnail-width) - 2px);
height: calc(var(--thumbnail-height) - 2px);
&.missingThumbnailImage {
border: 1px dashed rgb(132 132 132);
padding: 7px;
> .thumbnailImage {
display: none;
}
}
> .thumbnailImage {
width: 100%;
opacity: 0.9;
}
}
&:is(:active, :focus) {
outline: 0;
}
&:last-of-type > .thumbnail {
margin-bottom: 10px;
}
&:focus > .thumbnail,
.thumbnail:hover {
border-color: var(--thumbnail-hover-color);
> .thumbnailImage {
opacity: 0.95;
}
}
}
}
.treeWithDeepNesting > .treeItem,