Given that the `enableXfa` parameter must to be passed to the API/Worker, and thus included in the `getDocument` call, it's not necessary to include it when initializing the `PDFViewer`-instance used in the default viewer. (Also, in `AppOptions`, the parameter is clearly marked with `OptionKind.API`.)
Furthermore, we probably don't want to display the fallback bar (in Firefox) for XFA documents when `enableXfa = true` is set.
- add an option to enable XFA rendering if any;
- for now, let the canvas layer: it could be useful to implement XFAF forms (embedded pdf in xml stream for the background and xfa form for the foreground);
- ui elements in template DOM are pretty close to their html counterpart so we generate a fake html DOM from template one:
- it makes easier to translate template properties to html ones;
- it makes faster the creation of the html element in the main thread.
It seems reasonable to place this alongside the *similar* `getFilenameFromUrl` helper function. This way, with the changes in the next patch, we also avoid having to expose the `isDataScheme` function in the API itself and we instead expose `getPdfFilenameFromUrl` in the API (which feels overall more appropriate).
The *main* purpose of this patch is to allow scripting to be used together with the viewer components, note the updated "simpleviewer"/"singlepageviewer" examples, in addition to the full default viewer.
Given how the scripting functionality is currently implemented in the default viewer, trying to re-use this with the standalone viewer components would be *very* hard and ideally you'd want it to work out-of-the-box.
For an initial implementation, in the default viewer, of the scripting functionality it probably made sense to simply dump all of the code in the `app.js` file, however that cannot be used with the viewer components.
To address this, the functionality is moved into a new `PDFScriptingManager` class which can thus be handled in the same way as all other viewer components (and e.g. be passed to the `BaseViewer`-implementations).
Obviously the scripting functionality needs quite a lot of data, during its initialization, and for the default viewer we want to maintain the current way of doing the lookups since that helps avoid a number of redundant API-calls.
To that end, the `PDFScriptingManager` implementation accepts (optional) factories/functions such that we can maintain the current behaviour for the default viewer. For the viewer components specifically, fallback code-paths are provided to ensure that scripting will "just work"[1].
Besides moving the viewer handling of the scripting code to its own file/class, this patch also takes the opportunity to re-factor the functionality into a number of helper methods to improve overall readability[2].
Note that it's definitely possible that the `PDFScriptingManager` class could be improved even further (e.g. for general re-use), since it's still heavily tailored to the default viewer use-case, however I believe that this patch is still a good step forward overall.
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[1] Obviously *all* the relevant document properties might not be available in the viewer components use-case (e.g. the various URLs), but most things should work just fine.
[2] The old `PDFViewerApplication._initializeJavaScript` method, where everything was simply inlined, have over time (in my opinion) become quite large and somewhat difficult to *easily* reason about.
These changes will be necessary for the next patch, since we don't want to accidentally pull in the entire default viewer in the standalone viewer components.
Rather than having to spell out the English fallback strings at *every* single `IL10n.get` call-site throughout the viewer, we can simplify things by collecting them in *one* central spot.
This provides a much better overview of the fallback l10n strings used, which makes future changes easier and ensures that fallback strings occuring in multiple places cannot accidentally get out of sync.
Furthermore, by making the `fallback` parameter of the `IL10n.get` method *optional*[1] many of the call-sites (and their surrounding code) become a lot less verbose.
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[1] It's obviously still possible to pass in a fallback string, it's just not required.
The only reason, as far as I can tell, for parsing the Metadata on the main-thread is how it was originally implemented. When Metadata support was first implemented, it utilized the [`DOMParser`](https://developer.mozilla.org/en-US/docs/Web/API/DOMParser) which isn't available in workers.
Today, with the custom XML-parser being used, that's no longer an issue and it seems reasonable to move the Metadata parsing to the worker-thread[1], since that's where all parsing should happen (for performance reasons).
Based on these changes, we'll be able to reduce the now unnecessary duplication of the XML-parser (and related code) in both of the *built* `pdf.js`/`pdf.worker.js` files.
Finally, this patch changes the `_repair` method to use "Array + join" rather than string concatenation.
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[1] This needed the previous patch, to enable sending of `Map`s between threads with workers disabled.
*This is somewhat similar to PR 12931.*
For PDF documents where fonts are completely missing in the /Resources dictionaries, there's basically no "correct" way of rendering the document.
Hence it's very unlikely that another PDF viewer will do a better job than PDF.js in these cases, and consequently it seems highly questionable if the fallback bar really helps here.
Given that these event listeners should essentially never be needed, but are included simply to avoid breakage in edge-cases, it can't hurt to make this code slightly less verbose.
Given that these HTML elements are not being used at all in `MOZCENTRAL`-builds, note the preprocessor check in `PDFViewerApplication._otherError`, we obviously don't need the HTML code either.
Some of the localization strings (e.g. "loading_error") are repeated multiple times throughout the `web/app.js` file, which means that we need to duplicate the fallback strings as well. Furthermore, the signature of the `IL10n.get` method makes the call-sites quite verbose.
By adding a new helper method, in `PDFViewerApplication`, we're able to gather the localization fallback strings in one central spot in `web/app.js` and also make the lookup of the error/warning messages more compact.
This code is *very* old and it even predates the existence of arrow functions. Hence we can now reduce the overall verbosity by not having to explicitly spell out `PDFViewerApplication` everywhere.
This feature was Firefox-specific, and it's now been removed from the HTML specification and it's disabled by default starting with Firefox 85. Hence it seems completely unnecessary to keep this code in the default viewer.
Please refer to https://groups.google.com/g/mozilla.dev.platform/c/tc11BCenm2c and the resources that it links to.
Given that we don't focus the viewer *itself* (among other things) when the viewer is embedded, I suppose that it makes some sense to not focus the `PasswordPrompt` input-field either on load.
In order to improve the overall UX here, if an *incorrect* password was provided we'll still focus the input-field.
Fixes 12951 (assuming we care to do so, of course).
With PR 10539, we'll now always attempt to fallback to the PDF.js built-in font renderer for fonts that fail to load (i.e. are rejected by the sanitizer). Generally speaking, these errors are the result of insufficient validation in the PDF.js font code, however in almost all cases we've seen thus far our built-in font renderer manages just fine.
However, we still trigger the `onUnsupportedFeature` reporting, which in Firefox causes the fallback bar to be displayed. Given that, in a majority of cases[1], things look fine it seems unfortunate to bother the user with the fallback bar here.
Note that even though we no longer show the fallback bar in this case, we still report telemetry as before.
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[1] The only *known* case where things aren't fine with the built-in font renderer is issue 10232, however that document is sufficiently broken that there's a couple of other things that will trigger the fallback bar.
- For wrapped scrolling, we unfortunately need to do a fair bit of parsing of the *current* page layout. Compared to e.g. the spread-modes, where we can easily tell how the pages are laid out, with wrapped scrolling we cannot tell without actually checking. In particular documents with varying page sizes require some care, since we need to check all pages on the "row" of the current page are visible and that there aren't any "holes" present. Otherwise, in the general case, there's a risk that we'd skip over pages if we'd simply always advance to the previous/next "row" in wrapped scrolling.
- For horizontal scrolling, this patch simply maintains the current behaviour of advancing *one* page at a time. The reason for this is to prevent inconsistent behaviour for the next and previous cases, since those cannot be handled identically. For the next-case, it'd obviously be simple to advance to the first not completely visible page. However for the previous-case, we'd only be able to go back *one* page since it's not possible to (easily) determine the page layout of non-visible pages (documents with varying page sizes being a particular issue).
- For vertical scrolling, this patch maintains the current behaviour by default. When spread-modes are being used, we'll now attempt to advance to the next *spread*, rather than just the next page, whenever possible. To prevent skipping over a page, this two-page advance will only apply when both pages of the current spread are visible (to avoid breaking documents with varying page sizes) and when the second page in the current spread is fully visible *horizontally* (to handle larger zoom values).
In order to reduce the performance impact of these changes, note that the previous/next-functionality will only call `getVisibleElements` for the scroll/spread-modes where that's necessary and that "normal" vertical scrolling is thus unaffected by these changes.
To support these changes, the `getVisibleElements` helper function will now also include the `widthPercent` in addition to the existing `percent` property.
The `PDFViewer._updateHelper` method is changed slightly w.r.t. updating the `currentPageNumber` for the non-vertical/spread modes, i.e. won't affect "normal" vertical scrolling, since that helped simplify the overall calculation of the page advance.
Finally, these new `BaseViewer` methods also allow (some) simplification of previous/next-page functionality in various viewer components.
*Please note:* There's one thing that this patch does not attempt to change, namely disabling of the previous/next toolbarButtons respectively the firstPage/lastPage secondaryToolbarButtons. The reason for this is that doing so would add quite a bit of complexity in general, and if for some reason `BaseViewer._getPageAdvance` would get things wrong we could end up incorrectly disabling the buttons. Hence it seemed overall safer to *not* touch this, and accept that the buttons won't be `disabled` despite in some edge-cases no further scrolling being possible.
Note first of all how the `PDFDocumentProxy.getJSActions` method in the API caches the result, which makes repeated lookups cheap enough to not really be an issue.
Secondly, with the previous patch, we're now only dispatching "pageopen"/"pageclose"-events when there's actually a sandbox that listens for them.
All-in-all, with these changes we can thus simplify the default-viewer "pageopen"-event handler a fair bit.
The "pageopen"/"pageclose"-events are only necessary if, and only if, there's actually a sandbox to dispatch the events in. Hence we shouldn't dispatch those events unconditionally, as soon as `enableScripting` is set, but rather initialize that functionality only when needed.
Furthermore, in `web/app.js`, there's currently a bug since we're attempting to *manually* simulate a "pageopen"-event for a page that may not actually have been rendered at the time. With the modified `BaseViewer.initializeScriptingEvents` method, we'll now dispatch a correct "pageopen"-event here.
There's built-in ESLint rule, see `sort-imports`, to ensure that all `import`-statements are sorted alphabetically, since that often helps with readability.
Unfortunately there's no corresponding rule to sort `export`-statements alphabetically, however there's an ESLint plugin which does this; please see https://www.npmjs.com/package/eslint-plugin-sort-exports
The only downside here is that it's not automatically fixable, but the re-ordering is a one-time "cost" and the plugin will help maintain a *consistent* ordering of `export`-statements in the future.
*Note:* To reduce the possibility of introducing any errors here, the re-ordering was done by simply selecting the relevant lines and then using the built-in sort-functionality of my editor.
This implementation is inspired by the behaviour in (recent versions of) Adobe Reader, since it leads to reasonably simple and straightforward code as far as I'm concerned.
*Specifically:* We'll only consider *one* destination per page when finding/highlighting the current outline item, which is similar to e.g. Adobe Reader, and we choose the *first* outline item at the *lowest* level of the outline tree.
Given that this functionality requires not only parsing of the `outline`, but looking up *all* of the destinations in the document, this feature can when initialized have a non-trivial performance overhead for larger PDF documents.
In an attempt to reduce the performance impact, the following steps are taken here:
- The "find current outline item"-functionality will only be enabled once *one* page has rendered and *all* the pages have been loaded[1], to prevent it interfering with data regular fetching/parsing early on during document loading and viewer initialization.
- With the exception of a couple of small and simple `eventBus`-listeners, in `PDFOutlineViewer`, this new functionality is initialized *lazily* the first time that the user clicks on the `currentOutlineItem`-button.
- The entire "find current outline item"-functionality is disabled when `disableAutoFetch = true` is set, since it can easily lead to the setting becoming essentially pointless[2] by triggering *a lot* of data fetching from a relatively minor viewer-feature.
- Fetch the destinations *individually*, since that's generally more efficient than using `PDFDocumentProxy.getDestinations` to fetch them all at once. Despite making the overall parsing code *more* asynchronous, and leading to a lot more main/worker-thread message passing, in practice this seems faster for larger documents.
Finally, we'll now always highlight an outline item that the user manually clicked on, since only highlighting when the new "find current outline item"-functionality is used seemed inconsistent.
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[1] Keep in mind that the `outline` itself already isn't fetched/parsed until at least *one* page has been rendered in the viewer.
[2] And also quite slow, since it can take a fair amount of time to fetch all of the necessary `destinations` data when `disableAutoFetch = true` is set.
Ensure that `PDFViewerApplication._contentLength` is always updated with the *correct* length, as returned by `PDFDocumentProxy.getDownloadInfo`, and only let the `PDFViewerApplication._initializeMetadata` method overwrite if it's not already been set.
Finally, in `PDFViewerApplication._initializeJavaScript`, the fallback `_contentLength` handling is now moved to just after the fallback `documentInfo` handling, such that all the fallback code is in one place within the method.
Note how the `onerror` functionality is not being used in the GENERIC `DownloadManager`, since we have no way of knowing if downloading succeeded.
Hence this functionality is only *possibly* useful in MOZCENTRAL builds, however as outlined in the existing comments it's unlikely to be helpful in practice. Generally speaking, if downloading failed once in [`PdfStreamConverter.jsm`](https://searchfox.org/mozilla-central/rev/809ac3660845fef6faf18ec210232fdadc0f1ad9/toolkit/components/pdfjs/content/PdfStreamConverter.jsm#294-406) it seems very likely that it would fail again; all-in-all I'm thus suggesting that we just remove the `onerror` functionality altogether here.
Currently this code is duplicated no less than three times in the `web/app.js` file, and by introducing a helper method we can avoid unnecessary repetition.
This method currently accepts a callback-function, which does feel a bit old fashioned now. At the time that this code was introduced, native Promises didn't exist yet and there's a custom Promise-implementation used instead.
However, today with Promises and async/await being used *a lot* it seems reasonable to change `DefaultExternalServices.fallback` to an `async` method instead such that the callback-function can be removed.
This follows the same principle as the `once` option that exists in the native `addEventListener` method, and will thus automatically remove an `EventBus` listener when it's invoked; see https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#Parameters
Finally, this patch also tweaks some the existing `EventBus`-code to use modern features such as optional chaining and logical assignment operators.
Given that we already have a `PresentationModeState`-enumeration, we should use that with the "presentationmodechanged" event rather than including separate properties. Note that this new behaviour, of including an enumeration-value in the event, is consistent with lots of other existing viewer-events.
To hopefully avoid issues in custom implementations of the default viewer, any attempt to access the removed properties will now throw.
Similar to e.g. the "locale" option, this in *only* done for those build-targets where the "sandboxBundleSrc" is actually defined.
With these changes we can remove an `AppOptions` dependency from the `web/generic_scripting.js` file, thus limiting *direct* `AppOptions` usage in the default viewer files.
Given that the `dispatchEventInSandbox` method (on the scripting-classes) is asynchronous, there's a very real risk that the events won't be dispatched/handled until *after* their associated functionality has actually run (with the "Will..." events being particularily susceptible to this issue).
To reduce the likelihood of that happening, we can simply `await` the `dispatchEventInSandbox` calls as necessary. A couple of methods are now marked as `async` to support these changes, however that shouldn't be a problem as far as I can tell.
*Please note:* Given that the browser "beforeprint"/"afterprint" events are *synchronous*, we unfortunately cannot await the `WillPrint`/`DidPrint` event dispatching. To fix this properly the web-platform would need support for asynchronous printing, and we'll thus have to hope that things work correctly anyway.
Note that currently the `DidSave` event is not *guaranteed* to actually be dispatched if there's any errors during saving, which is easily fixed by simply moving it to occur in the `finally`-handler in `PDFViewerApplication.save` method.
For the `WillPrint`/`DidPrint` events, things are unfortunately more complicated. Currently these events will *only* be dispatched iff the printing request comes from within the viewer itself (e.g. by the user clicking on the "Print" toolbar button), however printing can be triggered in a few additional ways:
- In the GENERIC viewer:
- By the <kbd>Ctrl</kbd>+<kbd>P</kbd> keyboard shortcut.
- In the MOZCENTRAL viewer, i.e. the Firefox built-in viewer:
- By the <kbd>Ctrl</kbd>+<kbd>P</kbd> keyboard shortcut.
- By the "Print" item, as found in either the Firefox "Hamburger menu" or in the browser-window menu.
In either of the cases described above, no `WillPrint`/`DidPrint` events will be dispatched. In order to *guarantee* that things work in the general case, we thus have to move the `dispatchEventInSandbox` calls to the "beforeprint"/"afterprint" event handlers instead.
Rather than calling `getJavaScript` in the API and then ignoring the result, when "enableScripting" is set, it should be more efficient/faster to simply skip it altogether instead.
Finally, the `setTimeout` call at the end of `PDFViewerApplication._initializeAutoPrint` is removed, since it doesn't seem necessary any more as far as I can tell.[1]
Note that when this functionality was originally added, back in PR 2839, it seems that `pagesPromise` simply waited for the `getPage` calls of *all* pages to resolve. Today, on the other hand, the viewer fetches *and* renders the first page *before* doing the remaining `getPage` calls, and only afterwards is `pagesPromise` resolved. Hence it's not really clear why we now need to delay printing even further with a `setTimeout` call.
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[1] The patch was tested with the following documents: https://github.com/mozilla/pdf.js/blob/master/test/pdfs/bug1001080.pdf and https://github.com/mozilla/pdf.js/blob/master/test/pdfs/issue6106.pdf
These callbacks should not be necessary *before* the document has been initialized. Furthermore, move the functionality to a new helper-method since `PDFViewerApplication.load` is already quite large.
