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Merge pull request #18052 from Snuffleupagus/textLayer-only-ReadableS…
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…tream

Restore broken functionality and simplify the implementation in `src/display/text_layer.js`
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@Snuffleupagus
Snuffleupagus committed May 14, 2024
2 parents 298d721 + 8d86e18 commit c0b5d93
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Showing 3 changed files with 108 additions and 81 deletions.
133 changes: 61 additions & 72 deletions src/display/text_layer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@
/** @typedef {import("./display_utils").PageViewport} PageViewport */
/** @typedef {import("./api").TextContent} TextContent */

import { AbortException, Util } from "../shared/util.js";
import { AbortException, Util, warn } from "../shared/util.js";
import { setLayerDimensions } from "./display_utils.js";

/**
Expand Down Expand Up @@ -162,7 +162,7 @@ function getAscent(fontFamily) {
return DEFAULT_FONT_ASCENT;
}

function appendText(task, geom, styles) {
function appendText(task, geom) {
// Initialize all used properties to keep the caches monomorphic.
const textDiv = document.createElement("span");
const textDivProperties = {
Expand All @@ -176,7 +176,7 @@ function appendText(task, geom, styles) {

const tx = Util.transform(task._transform, geom.transform);
let angle = Math.atan2(tx[1], tx[0]);
const style = styles[geom.fontName];
const style = task._styleCache[geom.fontName];
if (style.vertical) {
angle += Math.PI / 2;
}
Expand Down Expand Up @@ -250,9 +250,7 @@ function appendText(task, geom, styles) {
textDivProperties.canvasWidth = style.vertical ? geom.height : geom.width;
}
task._textDivProperties.set(textDiv, textDivProperties);
if (task._isReadableStream) {
task._layoutText(textDiv);
}
task._layoutText(textDiv);
}

function layout(params) {
Expand Down Expand Up @@ -284,30 +282,11 @@ function layout(params) {
}
}

function render(task) {
if (task._canceled) {
return;
}
const textDivs = task._textDivs;
const capability = task._capability;
const textDivsLength = textDivs.length;

// No point in rendering many divs as it would make the browser
// unusable even after the divs are rendered.
if (textDivsLength > MAX_TEXT_DIVS_TO_RENDER) {
capability.resolve();
return;
}
class TextLayerRenderTask {
#reader = null;

if (!task._isReadableStream) {
for (const textDiv of textDivs) {
task._layoutText(textDiv);
}
}
capability.resolve();
}
#textContentSource = null;

class TextLayerRenderTask {
constructor({
textContentSource,
container,
Expand All @@ -316,14 +295,26 @@ class TextLayerRenderTask {
textDivProperties,
textContentItemsStr,
}) {
this._textContentSource = textContentSource;
this._isReadableStream = textContentSource instanceof ReadableStream;
if (textContentSource instanceof ReadableStream) {
this.#textContentSource = textContentSource;
} else if (
(typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) &&
typeof textContentSource === "object"
) {
this.#textContentSource = new ReadableStream({
start(controller) {
controller.enqueue(textContentSource);
controller.close();
},
});
} else {
throw new Error('No "textContentSource" parameter specified.');
}
this._container = this._rootContainer = container;
this._textDivs = textDivs || [];
this._textContentItemsStr = textContentItemsStr || [];
this._fontInspectorEnabled = !!globalThis.FontInspector?.enabled;

this._reader = null;
this._textDivProperties = textDivProperties || new WeakMap();
this._canceled = false;
this._capability = Promise.withResolvers();
Expand All @@ -335,6 +326,7 @@ class TextLayerRenderTask {
properties: null,
ctx: getCtx(),
};
this._styleCache = Object.create(null);
const { pageWidth, pageHeight, pageX, pageY } = viewport.rawDims;
this._transform = [1, 0, 0, -1, -pageX, pageY + pageHeight];
this._pageWidth = pageWidth;
Expand All @@ -346,6 +338,7 @@ class TextLayerRenderTask {
this._capability.promise
.finally(() => {
this._layoutTextParams = null;
this._styleCache = null;
})
.catch(() => {
// Avoid "Uncaught promise" messages in the console.
Expand All @@ -365,22 +358,33 @@ class TextLayerRenderTask {
*/
cancel() {
this._canceled = true;
if (this._reader) {
this._reader
.cancel(new AbortException("TextLayer task cancelled."))
.catch(() => {
// Avoid "Uncaught promise" messages in the console.
});
this._reader = null;
}
this._capability.reject(new AbortException("TextLayer task cancelled."));
const abortEx = new AbortException("TextLayer task cancelled.");

this.#reader?.cancel(abortEx).catch(() => {
// Avoid "Uncaught promise" messages in the console.
});
this.#reader = null;

this._capability.reject(abortEx);
}

/**
* @private
*/
_processItems(items, styleCache) {
_processItems(items) {
const textDivs = this._textDivs,
textContentItemsStr = this._textContentItemsStr;

for (const item of items) {
// No point in rendering many divs as it would make the browser
// unusable even after the divs are rendered.
if (textDivs.length > MAX_TEXT_DIVS_TO_RENDER) {
warn("Ignoring additional textDivs for performance reasons.");

this._processItems = () => {}; // Avoid multiple warnings for one page.
return;
}

if (item.str === undefined) {
if (
item.type === "beginMarkedContentProps" ||
Expand All @@ -398,8 +402,8 @@ class TextLayerRenderTask {
}
continue;
}
this._textContentItemsStr.push(item.str);
appendText(this, item, styleCache);
textContentItemsStr.push(item.str);
appendText(this, item);
}
}

Expand All @@ -426,37 +430,22 @@ class TextLayerRenderTask {
* @private
*/
_render() {
const { promise, resolve, reject } = Promise.withResolvers();
let styleCache = Object.create(null);

if (this._isReadableStream) {
const pump = () => {
this._reader.read().then(({ value, done }) => {
if (done) {
resolve();
return;
}
const styleCache = this._styleCache;

Object.assign(styleCache, value.styles);
this._processItems(value.items, styleCache);
pump();
}, reject);
};

this._reader = this._textContentSource.getReader();
pump();
} else if (this._textContentSource) {
const { items, styles } = this._textContentSource;
this._processItems(items, styles);
resolve();
} else {
throw new Error('No "textContentSource" parameter specified.');
}
const pump = () => {
this.#reader.read().then(({ value, done }) => {
if (done) {
this._capability.resolve();
return;
}

promise.then(() => {
styleCache = null;
render(this);
}, this._capability.reject);
Object.assign(styleCache, value.styles);
this._processItems(value.items);
pump();
}, this._capability.reject);
};
this.#reader = this.#textContentSource.getReader();
pump();
}
}

Expand Down
14 changes: 5 additions & 9 deletions test/driver.js
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Original file line number Diff line number Diff line change
Expand Up @@ -335,15 +335,11 @@ class Rasterize {

await task.promise;

const { _pageWidth, _pageHeight, _textContentSource, _textDivs } = task;
const { _pageWidth, _pageHeight, _textDivs } = task;
const boxes = [];
let posRegex;
for (
let i = 0, j = 0, ii = _textContentSource.items.length;
i < ii;
i++
) {
const { width, height, type } = _textContentSource.items[i];
let j = 0,
posRegex;
for (const { width, height, type } of textContent.items) {
if (type) {
continue;
}
Expand Down Expand Up @@ -396,7 +392,7 @@ class Rasterize {

drawLayer.destroy();
} catch (reason) {
throw new Error(`Rasterize.textLayer: "${reason?.message}".`);
throw new Error(`Rasterize.highlightLayer: "${reason?.message}".`);
}
}

Expand Down
42 changes: 42 additions & 0 deletions test/unit/text_layer_spec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -58,5 +58,47 @@ describe("textLayer", function () {
"",
"page 1 / 3",
]);

await loadingTask.destroy();
});

it("creates textLayer from TextContent", async function () {
if (isNodeJS) {
pending("document.createElement is not supported in Node.js.");
}
const loadingTask = getDocument(buildGetDocumentParams("basicapi.pdf"));
const pdfDocument = await loadingTask.promise;
const page = await pdfDocument.getPage(1);

const textContentItemsStr = [];

const textLayerRenderTask = renderTextLayer({
textContentSource: await page.getTextContent(),
container: document.createElement("div"),
viewport: page.getViewport({ scale: 1 }),
textContentItemsStr,
});
expect(textLayerRenderTask instanceof TextLayerRenderTask).toEqual(true);

await textLayerRenderTask.promise;
expect(textContentItemsStr).toEqual([
"Table Of Content",
"",
"Chapter 1",
" ",
"..........................................................",
" ",
"2",
"",
"Paragraph 1.1",
" ",
"......................................................",
" ",
"3",
"",
"page 1 / 3",
]);

await loadingTask.destroy();
});
});

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