Commit Graph

425 Commits

Author SHA1 Message Date
Calixte Denizet
5875ebb1ca Display widget signature
- but don't validate them for now;
  - Firefox will display a bar to warn that the signature validation is not supported (see https://bugzilla.mozilla.org/show_bug.cgi?id=854315)
  - almost all (all ?) pdf readers display signatures;
  - validation is done in edge but for now it's behind a pref.
2021-04-10 19:13:28 +02:00
Jonas Jenwald
fa86a192f9 Remove the URL polyfill
Based on this compatibility information, given that IE 11 is now *explicitly* unsupported, we should no longer need to bundle a `URL` polyfill in any builds: https://developer.mozilla.org/en-US/docs/Web/API/URL/URL#browser_compatibility

Note that the caveat listed for older Safari-versions doesn't apply to any code in the PDF.js library, since we never call `new URL(url, undefined)` in the code-base.

Note also that Node.js has a web-compatible `URL` implementation, which according to the "History" section at https://nodejs.org/api/url.html#url_the_whatwg_url_api has been available since Node.js `10.0.0` (according to https://nodejs.org/en/about/releases/ that branch is one month away from being EOL-ed).
2021-03-29 18:00:36 +02:00
Jonas Jenwald
5b5061afa8 Enable the ESLint no-var rule globally
A significant portion of the code-base has now been converted to use `let`/`const`, rather than `var`, hence it should be possible to simply enable the ESLint `no-var` rule globally.
This way we can ensure that new code won't accidentally use `var`, and it also removes the need to manually enable the rule in various folders.

Obviously it makes sense to continue the efforts to replace `var`, but that should probably happen on a file and/or folder basis.

Please note that this patch excludes the following code:
 - The `extensions/` folder, since that seemed easiest for now (and I don't know exactly what the support situation is for the Chromium-extension).

 - The entire `external/` folder is ignored, since most of it's currently excluded from linting.
   For the code that isn't imported from elsewhere (and should be ignored), we should probably (at some point) bring the code up to the same linting/formatting standard as the rest of the code-base.

 - Various files in the `test/` folder are ignored, as necessary, since the way that a lot of this code is loaded will require some care (or perhaps larger re-factoring) when removing `var` usage.
2021-03-13 16:12:53 +01:00
Jonas Jenwald
a0e584eeb2 Replace the objectFromEntries helper function with an objectFromMap one instead
Given that it's only used with `Map`s, and that it's currently implemented in such a way that we (indirectly) must iterate through the data *twice*, some simplification cannot hurt here.
Note that the only reason that we're not using `Object.fromEntries(...)` directly, at each call-site, is that that one won't guarantee that a `null` prototype is being used.
2021-03-11 16:37:34 +01:00
Jonas Jenwald
9a9a5b2365 Replace the compareByteArrays functions, in src/core/crypto.js, with the isArrayEqual helper function
The `compareByteArrays` is first of all duplicated in multiple closures in the `src/core/crypto.js` file. Secondly, despite its name, it's also functionally equivalent to the now existing `isArrayEqual` helper function.

The `isArrayEqual` helper function is changed to use a standard `for`-loop, rather than `Array.prototype.every`, since that ought to be slightly more efficient given that we're now using it with (potentially) larger data.
2021-02-26 15:51:32 +01:00
Jonas Jenwald
70d1869fe5 Remove the, strictly unnecessary, closure and variable shadowing from createObjectURL
Note that this particular helper function is, with the exception of the `GENERIC` default viewer and the (unsupported) SVG-backend, mostly unused at this point in time. Hence we should be able to clean-up this helper function slightly.

Also, fixes a small inconsistency in the `SVGGraphics` initialization in the viewer, by passing in the `disableCreateObjectURL` compatibility-option. Given that the SVG-backend isn't officially supported/recommended this shouldn't have been an issue, but given that I spotted this it can't hurt to fix it.
2021-02-25 16:34:23 +01:00
Jonas Jenwald
d366bbdf51 Move the encodeToXmlString helper function to src/core/core_utils.js
With the previous patch this function is now *only* accessed on the worker-thread, hence it's no longer necessary to include it in the *built* `pdf.js` file.
2021-02-17 13:12:01 +01:00
Jonas Jenwald
b66f294f64 Move the XML-parser to the src/core/-folder
With the previous patch this functionality is now *only* accessed on the worker-thread, hence it's no longer necessary to include it in the *built* `pdf.js` file.
2021-02-17 13:12:01 +01:00
Jonas Jenwald
cc3a6563ee Move the Metadata parsing to the worker-thread
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.

---
[1] This needed the previous patch, to enable sending of `Map`s between threads with workers disabled.
2021-02-17 13:12:01 +01:00
Jonas Jenwald
31098c404d
Use Math.hypot, instead of Math.sqrt with manual squaring (#12973)
When the PDF.js project started `Math.hypot` didn't exist yet, and until recently we still supported browsers (IE 11) without a native `Math.hypot` implementation; please see this compatibility information: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/hypot#browser_compatibility

Furthermore, somewhat recently there were performance improvements of `Math.hypot` in Firefox; see https://bugzilla.mozilla.org/show_bug.cgi?id=1648820

Finally, this patch also replaces a couple of multiplications with the exponentiation operator.
2021-02-10 12:28:49 +01:00
Calixte Denizet
0ff5cd7eb5 XFA - Add a parser for XFA files
- the parser is base on a class extending XMLParserBase
 - it handle xml namespaces:
   * each namespace is assocated with a builder
   * builder builds nodes belonging to the namespace
   * when a node is inserted in the parent namespace compatibility is checked (if required)
 - to avoid name collision between xml names and object properties, use Symbol.
2021-02-01 13:45:31 +01:00
Calixte Denizet
34d2e72df2 JS - Fix mouse event names
- fix issue #12895
2021-01-23 20:26:22 +01:00
calixteman
1de1ae0be6
Merge pull request #12838 from calixteman/authors
[api-minor] Change the "dc:creator" Metadata field to an Array
2021-01-12 02:44:58 -08:00
Calixte Denizet
43d5512f5c [api-minor] Change the "dc:creator" Metadata field to an Array
- add scripting support for doc.info.authors
 - doc.info.metadata is the raw string with xml code
2021-01-11 21:34:07 +01:00
Jonas Jenwald
81525fd446 Use ESLint to ensure that exports are sorted alphabetically
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.
2021-01-09 20:37:51 +01:00
Calixte Denizet
56424967f2 Fix encoding issues when printing/saving a form with non-ascii characters 2021-01-05 17:23:18 +01:00
Calixte Denizet
1e2173f038 JS - Collect and execute actions at doc and pages level
* the goal is to execute actions like Open or OpenAction
 * can be tested with issue6106.pdf (auto-print)
 * once #12701 is merged, we can add page actions
2020-12-18 20:03:59 +01:00
Jonas Jenwald
499d865ebf Change the minimum "supported" version of the Safari-browser to Safari 10
According to https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#faq-support, Safari 9 is still listed as "mostly supported".

Given that the *last* release from the Safari 9 branch was on [September 1, 2016](https://en.wikipedia.org/wiki/Safari_version_history#Safari_9), it's questionable at least to me if it actually makes sense for us to even pretend to "support" such an old browser.
Especially when the *first* release from the Safari 10 branch was on [September 20, 2016](https://en.wikipedia.org/wiki/Safari_version_history#Safari_10), which is now over four years ago.

Based on the MDN compatibility data, this patch thus removes the following polyfills:
 - `TypedArray.prototype.slice()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice#Browser_compatibility
 - `String.prototype.codePointAt()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt#Browser_compatibility
 - `String.fromCodePoint()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCodePoint#Browser_compatibility
2020-12-15 09:49:32 +01:00
Jonas Jenwald
a2874b380a Remove the remaining IE 11 polyfills
We really ought to settle on the *lowest* supported versions of various browsers[1], since that should allow even more clean-up, but given that https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#faq-support *explicitly* lists IE 11 as unsupported after PDF.js version `2.6.347` there's a number of polyfills that are no longer needed.

Based on the MDN compatibility data, this patch thus removes the following polyfills:
 - `String.prototype.startsWith()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith#Browser_compatibility

 - `String.prototype.endsWith()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/endsWith#Browser_compatibility

  - `String.prototype.includes()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes#Browser_compatibility

 - `Array.prototype.includes()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes#Browser_compatibility

  - `Array.from()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from#Browser_compatibility

  - `Object.assign()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Browser_compatibility

  - `Math.log2()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/log2#Browser_compatibility

  - `Number.isNaN()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN#Browser_compatibility

  - `Number.isInteger()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isInteger#Browser_compatibility

  - `Map.prototype.entries()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/entries#Browser_compatibility

  - `Set.prototype.entries()`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/entries#Browser_compatibility

  - `WeakMap`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap#Browser_compatibility

  - `WeakSet`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet#Browser_compatibility

  - `Symbol`, see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol#Browser_compatibility

Finally, this patch also attempts to update the compatibility information for the remaining polyfills.

---
[1] For example: It's questionable if Safari 9 should be listed as supported, given that the last release from that branch was in 2016.
2020-12-14 14:31:25 +01:00
Jonas Jenwald
155c17c99a [Regression] Prevent the *built* pdf.scripting.js/pdf.sandbox.js files from accidentally including most of the main-thread code (PR 12631 follow-up)
*This is a recent regression, which I stumbled upon while working on cleaning-up the gulpfile related to `pdf.sandbox.js` building.*

By placing the `ColorConverters` functionality in the `src/display/display_utils.js` file, you end up including a *significant* chunk of the `pdf.js` file in the built `pdf.scripting.js`/`pdf.sandbox.js` files.
Given that I cannot imagine that this was actually intended, since it inflates the built files with unnecessary/unused code, this moves `ColorConverters` to a new file instead (thus breaking the dependencies).

To hopefully reduce the risk future bugs, along these lines, a big comment is also placed at the top of the new file.
Finally, the `ColorConverters` is converted to a class with static methods, since this felt slightly cleaner overall.
2020-12-04 14:17:26 +01:00
Jonas Jenwald
9602844368 Enable the ESLint no-useless-escape rule (PR 12551 follow-up)
Note that a number of these cases are covered by existing unit-tests, and a few others only matter for the development/build scripts.
Furthermore, I've also tried to the best of my ability to test each case *manually* to hopefully further reduce the likelihood of this patch introducing any bugs.

Please find additional details about the ESLint rule at https://eslint.org/docs/rules/no-useless-escape
2020-11-07 13:06:24 +01:00
Tim van der Meij
3e52098e29
Merge pull request #12555 from calixteman/color
Replace css color rgb(...) by #...
2020-11-02 23:55:39 +01:00
Calixte Denizet
9d11b51a3e Replace css color rgb(...) by #...
* it's faster to generate the color code in using a table for components
* it's very likely a way faster to parse (when setting the color in the canvas)
2020-11-02 10:25:04 +01:00
Jonas Jenwald
a177afc206 Fix some static static analyzer warnings (issue 11965)
This fixes only those warnings, as reported by https://lgtm.com/projects/g/mozilla/pdf.js?mode=list, that make sense (as far as I'm concerned).

Hence this patch leaves the following things unaddressed:
 - The "recommendation"-category, since it only complains about unused variables. However, note that all of those cases are purposely included and that there's thus ESLint-disable comments added to explictly allow them.
 - The "warning"-category, which still contains two complaints. However, as far as I can tell, they are both false positives.

Given first of all the false positives of the LGTM static analyzer, and secondly that we'd need to add (essentially duplicated) disable-comments for the unused variable cases, it's not entirely clear to me if we actually want to work towards including LGTM in the PDF.js project (e.g. running alongside Travis) or if we should just close issue 11965.
2020-11-01 12:08:38 +01:00
Jonas Jenwald
a1e5581a0b Let Annotation._collectActions return null when no actions are present
Rather than returning an *empty* Object[1] we should be returning `null` instead, since that's consistent with existing API-functionality.
To avoid having to *manually* track if the Object is empty, this patch also introduces a small helper function to check its size.
2020-10-30 13:23:05 +01:00
Jonas Jenwald
46e94cad17 Fix *some* errors reported by the ESLint no-useless-escape rule
This patch removes unnecessary escape-sequence in (mostly) strings, as a first step, since the ones in regular expressions probably requires more careful testing (just in case).
The only exception is a regular expression in `src/core/annotation.js`, since we should have both unit- and reference-tests for this code *and* given [this information on MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Character_Classes#Types):
 > Inside a character set, the dot loses its special meaning and matches a literal dot.

Please find additional details about the ESLint rule at https://eslint.org/docs/rules/no-useless-escape
2020-10-29 15:40:40 +01:00
Jonas Jenwald
9fc7cdcc9d Use a Map, rather than an Object, internally in the Catalog.openAction getter (PR 11644 follow-up)
This provides a work-around to avoid having to conditionally try to initialize the `openAction`-object in multiple places.
Given that `Object.fromEntries` doesn't seem to *guarantee* that a `null` prototype is used, we thus hack around that by using `Object.assign` with `Object.create(null)`.
2020-10-28 14:43:28 +01:00
Jonas Jenwald
666535be47 Prevent use of optional chaining and nullish coalescing in the src/shared/ folder
Given that this code is used on the worker-thread, where SystemJS is still used during development, we need to (for now) handle this folder the same way as the `src/core/` one.
2020-10-26 13:16:01 +01:00
Calixte Denizet
71ecc3129b Add the possibility to collect Javascript actions 2020-10-14 10:44:16 +02:00
Jonas Jenwald
9416b14e8b Re-factor how the ESLint no-var rule is enabled in the src/ folder
This simplifies/consolidates the ESLint configuration slightly in the `src/` folder, and prevents the addition of any new files where `var` is being used.[1]
Hence we no longer need to manually add `/* eslint no-var: error */` in files, which is easy to forget, and can instead disable the rule in the `src/core/` files where `var` is still in use.

---
[1] Obviously the `no-var` rule can, in the same way as every other rule, be disabled on a case-by-case basis where actually necessary.
2020-10-03 20:15:29 +02:00
Jonas Jenwald
2a7d1557f9 Enable the ESLint no-var rule in the src/shared/ folder
Previously this rule has been enabled in the `web/` folder, and in select files in the `src/` sub-folders.
In this case, enabling of this rule didn't actually require any further code changes.

Please find additional details about the ESLint rule at https://eslint.org/docs/rules/no-var
2020-10-03 08:27:45 +02:00
Calixte Denizet
0c8de5aaf9 Replace \n and \r by \n and \r when saving a string 2020-09-14 17:34:39 +02:00
Tim van der Meij
f9d56320f5
Merge pull request #12349 from calixteman/followup_12344
Follow-up of pr #12344
2020-09-09 23:40:53 +02:00
Calixte Denizet
908e7ae5e4 Set the modification date to the current day when saving 2020-09-09 19:06:39 +02:00
Calixte Denizet
64a6efd95e Follow-up of pr #12344 2020-09-09 11:46:02 +02:00
calixteman
68b99c59ee
Save form data in XFA datasets when pdf is a mix of acroforms and xfa (#12344)
* Move display/xml_parser.js in shared to use it in worker

* Save form data in XFA datasets when pdf is a mix of acroforms and xfa

Co-authored-by: Brendan Dahl <brendan.dahl@gmail.com>
2020-09-08 15:13:52 -07:00
Jonas Jenwald
babeae9448 Remove, manually implemented, DOM polyfills only necessary for IE 11 support
Please refer to the following compatibility information:
 - https://developer.mozilla.org/en-US/docs/Web/API/ChildNode/remove#Browser_compatibility
 - https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList/add#Browser_compatibility
 - https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList/remove#Browser_compatibility
 - https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList/toggle#Browser_compatibility

Finally, for the `pushState`/`replaceState` polyfills, please refer to PRs 10461 and 11318 for additional details.
2020-09-06 18:24:17 +02:00
Jonas Jenwald
449c7763d5 [api-minor] Only support browsers/environments that have *basic* support for Promise natively
Based on https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise#Browser_compatibility and https://caniuse.com/#feat=promises, all even remotely modern browsers already support *basic* `Promise` functionality natively.

The only reason for keeping the `Promise` polyfill (at all) is to be able to support recent additions to the specification, such as e.g. `finally` and `allSettled`.
Note that this patch will, on its own, remove support for IE 11/Edge (non-Chromium based) in both the general PDF.js library and the default viewer.
2020-09-06 13:45:56 +02:00
Jonas Jenwald
784a420027 Add support, in Dict.merge, for merging of "sub"-dictionaries
This allows for merging of dictionaries one level deeper than previously. This could be useful e.g. for /Resources dictionaries, where you want to e.g. merge their respective /Font dictionaries (and other) together rather than picking just the first one.
2020-08-30 23:18:32 +02:00
Calixte Denizet
1a6816ba98 Add support for saving forms 2020-08-12 10:32:59 +02:00
Tim van der Meij
8c162f57f7
Merge pull request #12175 from calixteman/textfield
Support textfield and choice widgets for printing
2020-08-07 00:20:29 +02:00
Calixte Denizet
1747d259f9 Support textfield and choice widgets for printing 2020-08-06 14:45:23 +02:00
Jonas Jenwald
16fa9dc4ea Add support for Object.fromEntries
This provides a simpler way of creating an `Object` from e.g. a `Map`, without having to manually iterate over it.
Please see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries
2020-08-06 14:39:51 +02:00
Brendan Dahl
ac494a2278 Add support for optional marked content.
Add a new method to the API to get the optional content configuration. Add
a new render task param that accepts the above configuration.
For now, the optional content is not controllable by the user in
the viewer, but renders with the default configuration in the PDF.

All of the test files added exhibit different uses of optional content.

Fixes #269.

Fix test to work with optional content.

- Change the stopAtErrors test to ensure the operator list has something,
  instead of asserting the exact number of operators.
2020-08-04 09:26:55 -07:00
Takashi Tamura
bc4648c0a6 Add types to functions exported as API in src/pdf.js. 2020-08-03 19:19:48 +09:00
Linus Gasser
f1bbfdc16d Add typescript definitions
This PR adds typescript definitions from the JSDoc already present.
It adds a new gulp-target 'types' that calls 'tsc', the typescript
compiler, to create the definitions.

To use the definitions, users can simply do the following:

```
import {getDocument, GlobalWorkerOptions} from "pdfjs-dist";
import pdfjsWorker from "pdfjs-dist/build/pdf.worker.entry";
GlobalWorkerOptions.workerSrc = pdfjsWorker;

const pdf = await getDocument("file:///some.pdf").promise;
```

Co-authored-by: @oBusk
Co-authored-by: @tamuratak
2020-07-30 11:10:37 +02:00
Takashi Tamura
473ea1f1a4 Make the detection of Node.js environments on Electron strict.
The main process and its child processes should be detected as Node.js environments.
2020-07-12 10:56:17 +09:00
Wojciech Maj
78970bbbe1
Replace non-inclusive "whitelist" term with "allowlist" 2020-06-29 17:15:14 +02:00
Jonas Jenwald
88fdb482b0 Move the isEmptyObj helper function from src/shared/util.js to test/unit/test_utils.js
Since this helper function is no longer used anywhere in the main code-base, but only in a couple of unit-tests, it's thus being moved to a more appropriate spot.

Finally, the implementation of `isEmptyObj` is also tweaked slightly by removing the manual loop.
2020-06-09 17:50:16 +02:00
Jonas Jenwald
0351852d74 [api-minor] Decode all JPEG images with the built-in PDF.js decoder in src/core/jpg.js
Currently some JPEG images are decoded by the built-in PDF.js decoder in `src/core/jpg.js`, while others attempt to use the browser JPEG decoder. This inconsistency seem unfortunate for a number of reasons:

 - It adds, compared to the other image formats supported in the PDF specification, a fair amount of code/complexity to the image handling in the PDF.js library.

 - The PDF specification support JPEG images with features, e.g. certain ColorSpaces, that browsers are unable to decode natively. Hence, determining if a JPEG image is possible to decode natively in the browser require a non-trivial amount of parsing. In particular, we're parsing (part of) the raw JPEG data to extract certain marker data and we also need to parse the ColorSpace for the JPEG image.

 - While some JPEG images may, for all intents and purposes, appear to be natively supported there's still cases where the browser may fail to decode some JPEG images. In order to support those cases, we've had to implement a fallback to the PDF.js JPEG decoder if there's any issues during the native decoding. This also means that it's no longer possible to simply send the JPEG image to the main-thread and continue parsing, but you now need to actually wait for the main-thread to indicate success/failure first.
   In practice this means that there's a code-path where the worker-thread is forced to wait for the main-thread, while the reverse should *always* be the case.

 - The native decoding, for anything except the *simplest* of JPEG images, result in increased peak memory usage because there's a handful of short-lived copies of the JPEG data (see PR 11707).
Furthermore this also leads to data being *parsed* on the main-thread, rather than the worker-thread, which you usually want to avoid for e.g. performance and UI-reponsiveness reasons.

 - Not all environments, e.g. Node.js, fully support native JPEG decoding. This has, historically, lead to some issues and support requests.

 - Different browsers may use different JPEG decoders, possibly leading to images being rendered slightly differently depending on the platform/browser where the PDF.js library is used.

Originally the implementation in `src/core/jpg.js` were unable to handle all of the JPEG images in the test-suite, but over the last couple of years I've fixed (hopefully) all of those issues.
At this point in time, there's two kinds of failure with this patch:

 - Changes which are basically imperceivable to the naked eye, where some pixels in the images are essentially off-by-one (in all components), which could probably be attributed to things such as different rounding behaviour in the browser/PDF.js JPEG decoder.
   This type of "failure" accounts for the *vast* majority of the total number of changes in the reference tests.

 - Changes where the JPEG images now looks *ever so slightly* blurrier than with the native browser decoder. For quite some time I've just assumed that this pointed to a general deficiency in the `src/core/jpg.js` implementation, however I've discovered when comparing two viewers side-by-side that the differences vanish at higher zoom levels (usually around 200% is enough).
   Basically if you disable [this downscaling in canvas.js](8fb82e939c/src/display/canvas.js (L2356-L2395)), which is what happens when zooming in, the differences simply vanish!
   Hence I'm pretty satisfied that there's no significant problems with the `src/core/jpg.js` implementation, and the problems are rather tied to the general quality of the downscaling algorithm used. It could even be seen as a positive that *all* images now share the same downscaling behaviour, since this actually fixes one old bug; see issue 7041.
2020-05-22 00:22:48 +02:00