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[api-minor] Replace the PromiseCapability with Promise.withResolvers()

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This replaces our custom `PromiseCapability`-class with the new native `Promise.withResolvers()` functionality, which does *almost* the same thing[1]; please see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers

The only difference is that `PromiseCapability` also had a `settled`-getter, which was however not widely used and the call-sites can either be removed or re-factored to avoid it. In particular:
 - In `src/display/api.js` we can tweak the `PDFObjects`-class to use a "special" initial data-value and just compare against that, in order to replace the `settled`-state.
 - In `web/app.js` we change the only case to manually track the `settled`-state, which should hopefully be OK given how this is being used.
 - In `web/pdf_outline_viewer.js` we can remove the `settled`-checks, since the code should work just fine without it. The only thing that could potentially happen is that we try to `resolve` a Promise multiple times, which is however *not* a problem since the value of a Promise cannot be changed once fulfilled or rejected.
 - In `web/pdf_viewer.js` we can remove the `settled`-checks, since the code should work fine without them:
     - For the `_onePageRenderedCapability` case the `settled`-check is used in a `EventBus`-listener which is *removed* on its first (valid) invocation.
     - For the `_pagesCapability` case the `settled`-check is used in a print-related helper that works just fine with "only" the other checks.
 - In `test/unit/api_spec.js` we can change the few relevant cases to manually track the `settled`-state, since this is both simple and *test-only* code.

---
[1] In browsers/environments that lack native support, note [the compatibility data](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers#browser_compatibility), it'll be polyfilled via the `core-js` library (but only in `legacy` builds).
This commit is contained in:
Jonas Jenwald 2024-03-28 16:42:37 +01:00
parent 55db43966e
commit e4d0e84802
28 changed files with 159 additions and 252 deletions
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14
src/display/text_layer.js
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@ -16,7 +16,7 @@
/** @typedef {import("./display_utils").PageViewport} PageViewport */
/** @typedef {import("./api").TextContent} TextContent */
import { AbortException, PromiseCapability, Util } from "../shared/util.js";
import { AbortException, Util } from "../shared/util.js";
import { setLayerDimensions } from "./display_utils.js";
/**
@ -326,7 +326,7 @@ class TextLayerRenderTask {
this._reader = null;
this._textDivProperties = textDivProperties || new WeakMap();
this._canceled = false;
this._capability = new PromiseCapability();
this._capability = Promise.withResolvers();
this._layoutTextParams = {
prevFontSize: null,
prevFontFamily: null,
@ -426,21 +426,21 @@ class TextLayerRenderTask {
* @private
*/
_render() {
const capability = new PromiseCapability();
const { promise, resolve, reject } = Promise.withResolvers();
let styleCache = Object.create(null);
if (this._isReadableStream) {
const pump = () => {
this._reader.read().then(({ value, done }) => {
if (done) {
capability.resolve();
resolve();
return;
}
Object.assign(styleCache, value.styles);
this._processItems(value.items, styleCache);
pump();
}, capability.reject);
}, reject);
};
this._reader = this._textContentSource.getReader();
@ -448,12 +448,12 @@ class TextLayerRenderTask {
} else if (this._textContentSource) {
const { items, styles } = this._textContentSource;
this._processItems(items, styles);
capability.resolve();
resolve();
} else {
throw new Error('No "textContentSource" parameter specified.');
}
capability.promise.then(() => {
promise.then(() => {
styleCache = null;
render(this);
}, this._capability.reject);