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.
I happened to look at this code, and I can't for the life of me figure out why I didn't just implement it like this patch in the first place (since the current format feels overly verbose).
*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.
- Mark `BaseViewer.initializeScriptingEvents` as an `async` method, since that's actually how it's being used in the default viewer (see `PDFViewerApplication-_initializeJavaScript`).
- Change `BaseViewer._pageWidthScaleFactor` to access the *internal* scroll/spread-modes directly, rather than using the getters, since that's consistent with the rest of the code (and not just for these properties).
For reasons that I now can't for the life of me understand, I included handling of the `PresentationModeState.CHANGING`-case despite it not actually doing anything.
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.
The following checks are all unneeded, and could easily cause confusion when reading the code. (All of them are my fault as well, since I've sometimes added those checks without really thinking about the surrounding code.)
- In `PartialEvaluator.hasBlendModes` there cannot be any `MissingDataException`s thrown, given that the `Page.getOperatorList` method waits for all the necessary /Resources to load first. Furthermore, note also that if an error is thrown from `PartialEvaluator.hasBlendModes` then it'd completely break rendering of that page, since any errors thrown from `Page.getOperatorList` are simply sent to the main-thread.
- In `PartialEvaluator.handleColorN` there cannot be any `MissingDataException`s thrown, given that again the `Page.getOperatorList` method waits for all the necessary /Resources to load before operatorList parsing starts.
- In `XRef.readXRef` there cannot be any `MissingDataException`s thrown, given that we're *explicitly* requesting (and waiting for) the entire document in `pdfManagerReady` (in `src/core/worker.js`) before re-parsing of a corrupt document starts.
* don't set a value in annotationStorage by default:
- having an undefined when the annotation is rendered for saving/printing means nothing has changed so use normal appearance
- aims to fix https://bugzilla.mozilla.org/show_bug.cgi?id=1681687
* change the way to compute font size when this one is null in DA:
- make fontSize proportional to line height
- in multiline case, take into account the number of lines for text entered to adapt the font size
- use ascent of the fallback font instead of the one from pdf to position spans
- use TextMetrics.fontBoundingBoxAscent if available or
- use a basic heuristic to guess ascent in drawing char on a canvas
- compute ascent as a ratio of font height
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 `getComputedStyle` only works on visible elements, the result of PR 12354 is that if the viewer is placed in a *hidden* `iframe` the viewer will now be broken. This obviously wasn't the intention of that PR, hence I believe that we should limit the `position: absolute;` check slightly to avoid this.
