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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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23
web/pdf_outline_viewer.js
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@ -14,7 +14,6 @@
*/
import { BaseTreeViewer } from "./base_tree_viewer.js";
import { PromiseCapability } from "pdfjs-lib";
import { SidebarView } from "./ui_utils.js";
/**
@ -54,14 +53,9 @@ class PDFOutlineViewer extends BaseTreeViewer {
// If the capability is still pending, see the `_dispatchEvent`-method,
// we know that the `currentOutlineItem`-button can be enabled here.
if (
this._currentOutlineItemCapability &&
!this._currentOutlineItemCapability.settled
) {
this._currentOutlineItemCapability.resolve(
/* enabled = */ this._isPagesLoaded
);
}
this._currentOutlineItemCapability?.resolve(
/* enabled = */ this._isPagesLoaded
);
});
this.eventBus._on("sidebarviewchanged", evt => {
this._sidebarView = evt.view;
@ -76,12 +70,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
this._currentPageNumber = 1;
this._isPagesLoaded = null;
if (
this._currentOutlineItemCapability &&
!this._currentOutlineItemCapability.settled
) {
this._currentOutlineItemCapability.resolve(/* enabled = */ false);
}
this._currentOutlineItemCapability?.resolve(/* enabled = */ false);
this._currentOutlineItemCapability = null;
}
@ -89,7 +78,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
* @private
*/
_dispatchEvent(outlineCount) {
this._currentOutlineItemCapability = new PromiseCapability();
this._currentOutlineItemCapability = Promise.withResolvers();
if (
outlineCount === 0 ||
this._pdfDocument?.loadingParams.disableAutoFetch
@ -307,7 +296,7 @@ class PDFOutlineViewer extends BaseTreeViewer {
if (this._pageNumberToDestHashCapability) {
return this._pageNumberToDestHashCapability.promise;
}
this._pageNumberToDestHashCapability = new PromiseCapability();
this._pageNumberToDestHashCapability = Promise.withResolvers();
const pageNumberToDestHash = new Map(),
pageNumberNesting = new Map();