There's no particularily good reason, as far as I can tell, to not support a custom worker path in Node.js environments (even if workers aren't supported). This patch thus make the Node.js fake worker loader code-path consistent with the fallback code-path used with *browser* fake worker loader.
Finally, this patch also deprecates[1] the `fallbackWorkerSrc` functionality, except in Node.js, since the user should *always* provide correct worker options since the fallback is nothing more than a best-effort solution.
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[1] Although it probably shouldn't be removed until the next major version.
For performance reasons, and to avoid hanging the browser UI, the PDF.js library should *always* be used with web workers enabled.
At this point in time all of the supported browsers should have proper worker support, and Node.js is thus the only environment where workers aren't supported. Hence it no longer seems relevant/necessary to provide, by default, fake worker loaders for various JS builders/bundlers/frameworks in the PDF.js code itself.[1]
In order to simplify things, the fake worker loader code is thus simplified to now *only* support Node.js usage respectively "normal" browser usage out-of-the-box.[2]
*Please note:* The officially intended way of using the PDF.js library is with workers enabled, which can be done by setting `GlobalWorkerOptions.workerSrc`, `GlobalWorkerOptions.workerPort`, or manually providing a `PDFWorker` instance when calling `getDocument`.
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[1] Note that it's still possible to *manually* disable workers, simply my manually loading the built `pdf.worker.js` file into the (current) global scope, however this's mostly intended for testing/debugging purposes.
[2] Unfortunately some bundlers such as Webpack, when used with third-party deployments of the PDF.js library, will start to print `Critical dependency: ...` warnings when run against the built `pdf.js` file from this patch. The reason is that despite the `require` calls being protected by *runtime* `isNodeJS` checks, it's not possible to simply tell Webpack to just ignore the `require`; please see [Webpack issue 8826](https://github.com/webpack/webpack) and libraries such as [require-fool-webpack](https://github.com/sindresorhus/require-fool-webpack).
During initial parsing of every PDF document we're currently creating a few `1 kB` strings, in order to find certain commands needed for initialization.
This seems inefficient, not to mention completely unnecessary, since we can just as well search through the raw bytes directly instead (similar to other parts of the code-base). One small complication here is the need to support backwards search, which does add some amount of "duplication" to this function.
The main benefits here are:
- No longer necessary to allocate *temporary* `1 kB` strings during initial parsing, thus saving some memory.
- In practice, for well-formed PDF documents, the number of iterations required to find the commands are usually very low. (For the `tracemonkey.pdf` file, there's a *total* of only 30 loop iterations.)
Note that most (reasonably) modern browsers have supported this for a while now, see https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream#Browser_compatibility
By moving the polyfill into `src/shared/compatibility.js` we can thus get rid of the need to manually export/import `ReadableStream` and simply use it directly instead.
The only change here which *could* possibly lead to a difference in behavior is in the `isFetchSupported` function. Previously we attempted to check for the existence of a global `ReadableStream` implementation, which could now pass (assuming obviously that the preceding checks also succeeded).
However I'm not sure if that's a problem, since the previous check only confirmed the existence of a native `ReadableStream` implementation and not that it actually worked correctly. Finally it *could* just as well have been a globally registered polyfill from an application embedding the PDF.js library.
Given that the error in question is surfaced on the API-side, this patch makes the following changes:
- Updates the wording such that it'll hopefully be slightly easier for users to understand.
- Changes the plain `Error` to an `InvalidPDFException` instead, since that should work better with the existing Error handling.
- Adds a unit-test which loads an empty PDF document (and also improves a pre-existing `InvalidPDFException` message and its test-case).
Given how this method is currently used there shouldn't be any fonts loaded at the point in time where it's called, but it does seem like a bad idea to assume that that's always going to be the case. Since `PDFDocument.checkFirstPage` is already asynchronous, it's easy enough to simply await `Catalog.cleanup` here.
(The patch also makes a tiny simplification in a loop in `Catalog.cleanup`.)
In the PDF document in question, there's an ASCII85Decode inline image where the '>' part of EOD (end-of-data) marker is missing; hence the PDF document is corrupt.
Note that the XRef cache will only hold objects returned through `Parser.getObj`, and indirectly via `Lexer.getObj`. Since neither of those methods will ever return `undefined`, we can simply `assert` that when inserting objects into the cache and thus get rid of one function call when doing cache lookups.
Obviously this won't have a huge effect on performance, however `XRef.fetch` is usually called *a lot* in larger documents and this patch thus cannot hurt.
I'm slightly surprised that this hasn't actually caused any (known) bugs, but that may be more luck than anything else since it fortunately doesn't seem common for Streams to be defined inside of an 'ObjStm'.[1]
Note that in the `XRef.fetchUncompressed` method we're *not* caching Streams, and that for very good reasons too.
- Streams, especially the `DecodeStream` ones, can become *very* large once read. Hence caching them really isn't a good idea simply because of the (potential) memory impact of doing so.
- Attempting to read from the *same* Stream more than once won't work, unless it's `reset` in between, since using any method such as e.g. `getBytes` always starts at the current data position.
- Given that even the `src/core/` code is now fairly asynchronous, see e.g. the `PartialEvaluator`, it's generally impossible to assert that any one Stream isn't being accessed "concurrently" by e.g. different `getOperatorList` calls. Hence `reset`-ing a cached Streams isn't going to work in the general case.
All in all, I cannot understand why it'd ever be correct to cache Streams in the `XRef.fetchCompressed` method.
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[1] One example where that happens is the `issue3115r.pdf` file in the test-suite, where the streams in question are not actually used for anything within the PDF.js code.
- Change all occurences of `var` to `let`/`const`.
- Initialize the (temporary) Arrays with the correct sizes upfront.
- Inline the `isCmd` check. Obviously this won't make a huge difference, but given that the check is only relevant for corrupt documents it cannot hurt.
Having ran the entire test-suite locally with these `Number.isInteger` checks removed, there wasn't a single test failure anywhere; see also PR 8857.
Hence everything points to this being completely unnecessary now, and by removing this code there's thus fewer function calls being made in `XRef.fetchUncompressed`.
The contents of this comment hasn't been correct for *years*, ever since the library was properly split into main/worker-threads, so it's probably high time for this to be updated.
For documents with a Linearization dictionary the computed `startXRef` position will be relative to the raw file, rather than the actual PDF document itself (which begins with `%PDF-`).
Hence it's necessary to subtract `stream.start` in this case, since otherwise the `XRef.readXRef` method will increment the position too far resulting in parsing errors.
*Please note:* A a similar change was attempted in PR 5005, but it was subsequently backed out (in PR 5069) since other parts of the patch caused issues.
With these changes, it's possible to replace repeated function calls within a loop with just a single function call and subsequent assignment instead.
I've always disliked the solution in PR 10461, since it required changes to the `PDFHistory` code itself to deal with a bug in IE11.
Now that IE11 support is limited, it seems reasonable to remove these `pushState`/`replaceState` hacks from the main code-base and simply use polyfills instead.
For Popup annotation trigger elements consisting of an arbitrary polyline, you need to ensure that the 'stroke-width' is always non-zero since otherwise it's impossible to actually open/close the popup.
Unfortunately I don't believe that any of the test-suites can be used to test this, hence why no tests are included in the patch.
As we've seen in numerous other cases, avoiding unnecessary function calls is never a bad thing (even if the effect is probably tiny here).
With these changes we also avoid potentially two back-to-back `isDict` checks when evaluating possible Page nodes, and can also no longer accidentally pick a dictionary with an incorrect /Type.
For certain canvas-related errors (and probably others), the browser rendering exceptions may be propagated "as-is" to the PDF.js code. In this case, the exceptions are of the somewhat cryptic `NS_ERROR_FAILURE` type.
Unfortunately these aren't actual `Error`s, which thus ends up unintentionally triggering the `assert` in `PDFPageProxy._abortOperatorList`; sorry about that!
The bug report seem to suggest that we don't support UTF-16 strings with a BOM (byte order mark), which we *actually* do as evident by both the code and a unit-test.
The issue at play here is rather that we previously only supported big-endian UTF-16 BOM, and the `Title` string in the PDF document is using a *little-endian* UTF-16 BOM instead.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1593902
Rather than having to store a `PromiseCapability` on the `ObjectLoader` instances, we can simply convert `_walk` to be `async` and thus have the same functionality with native JavaScript instead.
I happened to look at this code and the way that the link target is set seems unecessarily convoluted, since we're using `Object.values` and `Array.prototype.includes` for *every* link being parsed.
Given that the number of link targets are so few, the easist solution honestly seem to be to just use a `switch` statement to do the link target mapping.
When the end of data has already been reached for the various Streams, the `getByte` methods will return `-1` to signal that to the caller. Note however that the current position obviously won't be incremented in this case, meaning that the `peekByte` methods will in this case *incorrectly* decrement the position.
Thankfully the corresponding `peekBytes` shouldn't be affected by this bug, since they decrement the current position with the *actually* returned number of bytes.
I'm not aware of any bugs caused by this blatant oversight, but that doesn't mean this shouldn't be fixed :-)
This will allow us to attempt to recover as much as possible of a page, rather than immediately failing, when a broken/unsupported ColorSpace is encountered. This patch thus extends the framework added in PRs such as e.g. 8240 and 8922, to also cover parsing of ColorSpaces.
The code in question is *only* relevant in non-`PRODUCTION` mode, i.e. the *development* version of the viewer run with `gulp server`, and has been completely unused at least since SystemJS was added.
I really cannot see any reason to keep this, since it's code which first of all isn't shipping and secondly isn't even being used in the development viewer.
When `ReadableStream` support was added to the `MessageHandler`, the `_onComObjOnMessage` function became more complex than previously.
All of the nested `if`/`else if`/`else` branches are now, at least in my opinion, making some of this code a bit difficult to follow. Hence this patch, which attempts to help readability by making use of early `return`s and `Error`s.
The patch also changes a couple of `var`/`let` occurences to `const`.
Note that using `in` leads to unnecessary stringification of the properties, which seems completely unnecessary here. To avoid future problems from these changes the `MessageHandler.on` method will now assert, in non-`PRODUCTION`/`TESTING` builds, that it's always called with a function as expected.
This patch also renames `callbacksCapabilities` to `callbackCapabilities`, note the removed "s", since using a double plural format looks a bit strange.
Given that the `isReply` property is an internal implementation detail, changing its type shouldn't be a problem. Note that by directly indicating if either data or an Error is sent, it's no longer necessary to use `in` when handling the callback.
Currently, for data in `ChunkedStream` instances, the `getMissingChunks` method is used in a couple of places to determine if data is already available or if it needs to be loaded.
When looking at how `ChunkedStream.getMissingChunks` is being used in the `ObjectLoader` you'll notice that we don't actually care about which *specific* chunks are missing, but rather only want essentially a yes/no answer to the "Is the data available?" question.
Furthermore, when looking at how `ChunkedStream.getMissingChunks` itself is implemented you'll notice that it (somewhat expectedly) always iterates over *all* chunks.
All in all, using `ChunkedStream.getMissingChunks` in the `ObjectLoader` seems like an unnecessary "heavy" and roundabout way to obtain a boolean value. However, it turns out there already exists a `ChunkedStream.allChunksLoaded` method, consisting of a *single* simple check, which seems like a perfect fit for the `ObjectLoader` use cases.
In particular, once the *entire* PDF document has been loaded (which is usually fairly quick with streaming enabled), you'd really want the `ObjectLoader` to be as simple/quick as possible (similar to e.g. loading a local files) which this patch should help with.
Note that I wouldn't expect this patch to have a huge effect on performance, but it will nonetheless save some CPU/memory resources when the `ObjectLoader` is used. (As usual this should help larger PDF documents, w.r.t. both file size and number of pages, the most.)
I completely overlooked this in PR 11281, but you obviously need to make similar changes in `PartialEvaluator.hasBlendModes` since it will otherwise ignore valid Blend Modes.
