This patch updates the minimum supported browsers as follows:
- Safari 16.4, which was released on 2023-03-27; see https://developer.apple.com/documentation/safari-release-notes/safari-16_4-release-notes
Nowadays we usually we try, where feasible and possible, to support browsers/environments that are about two years old. The reasons for limiting support to a slightly more recent Safari version include:
- Safari has always been slower, compared to other browsers, at implementing e.g. new JavaScript features.
- Trying to provide support for Safari is often difficult, and over the years we have seen *a lot* of bugs that are specific to Safari.
- Safari is, and has been for many years, only listed as "mostly" supported in the FAQ.
- This allows us to remove feature-testing, only relevant to Safari, from the main code-base.
By limiting support to only "recent" browsers we reduce the risk of holding back improvements of the built-in Firefox PDF Viewer, and also (significantly) reduce the maintenance/support burden for the PDF.js core contributors.
*Please note:* As always, the minimum supported browser version assumes that a `legacy`-build of the PDF.js library is being used; see https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#faq-support
This allows us to get rid of the `@private` JSDoc comments, which were
used to convey intent back when proper private methods could not be used
yet in JavaScript. This improves code readability/maintenance and enables
better usage validation by tooling such as ESlint.
These CSS rules were imported straight from mozilla-central, and contains a property that causes the RTL-rule to be skipped everywhere else (even when using the development viewer in Firefox).
This allows us to get rid of the `@private` JSDoc comments, which were
used to convey intent back when proper private methods could not be used
yet in JavaScript. This improves code readability/maintenance and enables
better usage validation by tooling such as ESlint.
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.
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[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).
With recent improvements to the `AppOptions`, e.g. with better validation and testing, one remaining "annoyance" is the `compatibilityParams` handling. Especially since there's only *a single* parameter left, limited to GENERIC builds.
To further reduce the amount of unnecessary code in e.g. the Firefox PDF Viewer, we can move the `compatibilityParams` handling into the user-options instead since that keeps the previous precedence order between default/user-options.
- Use slightly shorter variable names when initializing the preferences.
- Correctly copy the "old" preference-values before writing to storage, since Objects are passed by reference in JavaScript. (Only applies to the GENERIC viewer.)
- Use `await` fully when writing new preference-values to storage. (Only applies to the GENERIC viewer.)
- Stub the `get`-method in the Firefox PDF Viewer, since it's unused there nowadays.
This old method is essentially just adding, a small amount of, unnecessary indirection and we can easily invoke `PDFViewerApplication.open` directly from the extension-specific code instead.
The following are some highlights of this patch:
- In the Worker we only extract a *subset* of the potential contents of the `Usage` dictionary, to avoid having to implement/test a bunch of code that'd be completely unused in the viewer.
- In order to still allow the user to *manually* override the default visible layers in the viewer, the viewable/printable state is purposely *not* enforced during initialization in the `OptionalContentConfig` constructor.
- Printing will now always use the *default* visible layers, rather than using the same state as the viewer (as was the case previously).
This ensures that the printing-output will correctly take the `Usage` dictionary into account, and in practice toggling of visible layers rarely seem to be necessary except in the viewer itself (if at all).[1]
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[1] In the unlikely case that it'd ever be deemed necessary to support fine-grained control of optional content visibility during printing, some new (additional) UI would likely be needed to support that case.
The fact that the highlight-thickness can only be changed in "free" mode isn't really obvious visually in the toolbar, so attempt to provide at least some indication of the `disabled`-state by "dimming" the slider.
The function caretPositionFromPoint return the position within the last visible element
and sometimes there are some elements on top of the ones in the text layer.
So the idea is to hide the visible elements which aren't in the text layer in order
to get the right caret position.
