Given the way that "classes" were previously implemented in PDF.js, using regular functions and closures, there's a fair number of false positives when the `no-shadow` ESLint rule was enabled.
Note that while *some* of these `eslint-disable` statements can be removed if/when the relevant code is converted to proper `class`es, we'll probably never be able to get rid of all of them given our naming/coding conventions (however I don't really see this being a problem).
*This is part of a series of patches that will try to split PR 11566 into smaller chunks, to make reviewing more feasible.*
Once all the code has been fixed, we'll be able to eventually enable the ESLint no-shadow rule; see https://eslint.org/docs/rules/no-shadow
In practice it's extremely rare[1] for the padding to be zero in *all* components, hence it seems better to just set it directly rather than creating a temporary variable and checking for the "no padding"-case.
---
[1] In the `tracemonkey.pdf` file that only happens with `0.08%` of all text elements.
Please find additional details about the ESLint rule at https://eslint.org/docs/rules/prefer-const
With the recent introduction of Prettier this sort of mass enabling of ESLint rules becomes a lot easier, since the code will be automatically reformatted as necessary to account for e.g. changed line lengths.
Note that this patch is generated automatically, by using the ESLint `--fix` argument, and will thus require some additional clean-up (which is done separately).
After PR 9566, which removed all of the old Firefox extension code, the `FIREFOX` build flag is no longer used for anything.
It thus seems to me that it should be removed, for a couple of reasons:
- It's simply dead code now, which only serves to add confusion when looking at the `PDFJSDev` calls.
- It used to be that `MOZCENTRAL` and `FIREFOX` was *almost* always used together. However, ever since PR 9566 there's obviously been no effort put into keeping the `FIREFOX` build flags up to date.
- In the event that a new, Webextension based, Firefox addon is created in the future you'd still need to audit all `MOZCENTRAL` (and possibly `CHROME`) build flags to see what'd make sense for the addon.
In order to eventually get rid of SystemJS and start using native `import`s instead, we'll need to provide "complete" file identifiers since otherwise there'll be MIME type errors when attempting to use `import`.
Note that Prettier, purposely, has only limited [configuration options](https://prettier.io/docs/en/options.html). The configuration file is based on [the one in `mozilla central`](https://searchfox.org/mozilla-central/source/.prettierrc) with just a few additions (to avoid future breakage if the defaults ever changes).
Prettier is being used for a couple of reasons:
- To be consistent with `mozilla-central`, where Prettier is already in use across the tree.
- To ensure a *consistent* coding style everywhere, which is automatically enforced during linting (since Prettier is used as an ESLint plugin). This thus ends "all" formatting disussions once and for all, removing the need for review comments on most stylistic matters.
Many ESLint options are now redundant, and I've tried my best to remove all the now unnecessary options (but I may have missed some).
Note also that since Prettier considers the `printWidth` option as a guide, rather than a hard rule, this patch resorts to a small hack in the ESLint config to ensure that *comments* won't become too long.
*Please note:* This patch is generated automatically, by appending the `--fix` argument to the ESLint call used in the `gulp lint` task. It will thus require some additional clean-up, which will be done in a *separate* commit.
(On a more personal note, I'll readily admit that some of the changes Prettier makes are *extremely* ugly. However, in the name of consistency we'll probably have to live with that.)
One of the motivations for using `setAttribute` in the first place was to support more efficient DOM updates in the `expandTextDivs` method, since performance of the `enhanceTextSelection` mode can be somewhat bad when there's a lot of `textDivs` on the page.
With recent `TextLayer` changes/optimizations it's no longer necessary to store a complete `style`-string for every `textDiv`, and we can thus re-visit the `setAttribute` usage.
Note that with the current code, in `appendText`, there's only *one* string per `textDiv` which avoids a bunch of temporary strings. While the changes in this patch means that there's now *three* strings per `textDiv` instead, the total length of these strings are now quite a bit shorter (42 characters to be exact).
*This should obviously have been done in PR 11097, but for some reason I completely overlooked it; sorry about that.*
There's no good reason to update the font unless you're actually going to measure the width of the textContent. This can reduce unnecessary font switching a fair bit, even for documents which are somewhat simple/short (in e.g. the `tracemonkey.pdf` file this cuts the amount of font switches almost in half).
For performance reasons single-char text divs aren't being scaled, as outlined in a comment in `appendText`. Hence it doesn't seem necessary, or even a good idea, to unconditionally measuring the width of the text in `_layoutText`.
Furthermore, it's possible to re-use the same Array for all `textDiv`s on the page and the resulting padding string also becomes a lot more compact.
Please note that the `paddingLeft` branch was moved, since the padding values need to be ordered as `top, right, bottom, left`.
Finally, with this re-factoring it's no longer necessary to cache the original `style` string for every `textDiv` when `enhanceTextSelection` is enabled.
Given that browsers will reject padding values smaller than zero (which may be caused by limited numerical precision during calculations in the `expand` code), it makes no sense to include those when expanding the `textDiv`s.
The default size of these canvases seem to be `300 x 150` (two orders of magnitude larger than the ones in PR 10597), which probably is sufficient enough to matter since there's one such canvas for each textLayer that's rendered in the viewer.
Also fixes the incorrect rejection reason, i.e. one using a string rather than an `Error`, in the `TextLayerRenderTask.cancel` method.
This method creates quite a few intermediate strings on each call and
it's called often, even for smaller documents like the Tracemonkey
document. Scrolling from top to bottom in that document resulted in
12936 strings being created in this method. With this commit applied,
this is reduced to 3610 strings.
It is only used in a few places to handle prefixing style properties if
necessary. However, we used it only for `transform`, `transformOrigin`
and `borderRadius`, which according to Can I Use are supported natively
(unprefixed) in the browsers that PDF.js 2.0 supports. Therefore, we can
remove this class, which should help performance too since this avoids
extra function calls in parts of the code that are called often.
This patch adds Streams API support in getTextContent
so that we can stream data in chunks instead of fetching
whole data from worker thread to main thread. This patch
supports Streams API without changing the core functionality
of getTextContent.
Enqueue textContent directly at getTextContent in partialEvaluator.
Adds desiredSize and ready property in streamSink.
http://eslint.org/docs/rules/comma-danglehttp://eslint.org/docs/rules/object-curly-spacing
Given that we currently have quite inconsistent object formatting, fixing this in *one* big patch probably wouldn't be feasible (since I cannot imagine anyone wanting to review that); hence I've opted to try and do this piecewise instead.
Please note: This patch was created automatically, using the ESLint `--fix` command line option. In a couple of places this caused lines to become too long, and I've fixed those manually; please refer to the interdiff below for the only hand-edits in this patch.
```diff
diff --git a/src/display/canvas.js b/src/display/canvas.js
index 5739f6f2..4216b2d2 100644
--- a/src/display/canvas.js
+++ b/src/display/canvas.js
@@ -2071,7 +2071,7 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
var map = [];
for (var i = 0, ii = positions.length; i < ii; i += 2) {
map.push({ transform: [scaleX, 0, 0, scaleY, positions[i],
- positions[i + 1]], x: 0, y: 0, w: width, h: height, });
+ positions[i + 1]], x: 0, y: 0, w: width, h: height, });
}
this.paintInlineImageXObjectGroup(imgData, map);
},
diff --git a/src/display/svg.js b/src/display/svg.js
index 9eb05dfa..2aa21482 100644
--- a/src/display/svg.js
+++ b/src/display/svg.js
@@ -458,7 +458,11 @@ SVGGraphics = (function SVGGraphicsClosure() {
for (var x = 0; x < fnArrayLen; x++) {
var fnId = fnArray[x];
- opList.push({ 'fnId': fnId, 'fn': REVOPS[fnId], 'args': argsArray[x], });
+ opList.push({
+ 'fnId': fnId,
+ 'fn': REVOPS[fnId],
+ 'args': argsArray[x],
+ });
}
return opListToTree(opList);
},
```
Please see http://eslint.org/docs/rules/object-shorthand.
For the most part, these changes are of the search-and-replace kind, and the previously enabled `no-undef` rule should complement the tests in helping ensure that no stupid errors crept into to the patch.
Fixes extra canvas create calls.
Fixes unnecessary call of `new DOMCanvasFactory`.
Fixes undefined error of DOMCanvasFactory.
Fixes failures in some of the tests.
Fixes expected behaviour.
Remove unused vars.
See http://eslint.org/docs/rules/brace-style.
Having the opening/closing braces on the same line can often make the code slightly more difficult to read, in particular for `if`/`else if` statements, compared to using new lines.
This patch also, for consistency with `mozilla-central`, enables the [`no-iterator`](http://eslint.org/docs/rules/no-iterator) rule. Note that this rule didn't require a single code change.
I intended to provide proper benchmarking results here, as outlined in https://github.com/mozilla/pdf.js/wiki/Benchmarking-your-changes, but after wasting a couple of hours over the weekend getting weird results I gave up.
It appears that there's a lot of, i.e. way too much, variance between subsequent runs of `text` tests for the results to be meaningful.
(Previously I've only benchmarked `eq` tests, so I don't know if the `text` tests has never worked well or if it's a newer problem. For reference, please see the results of back-to-back benchmark runs on the current `master` with a *very* simple manifest file: [link here].)
Instead I used `console.time/timeEnd` in `appendText` and `expandTextDivs` to be able to compare the performance with/without the patch. The entire viewer was (skip-cache) reloaded between measurements, and the result are available here: [link here].
Given the troubles I've had with benchmarking, I've not yet computed any statistics on the results (e.g. mean, variance, confidence intervals, and so on).
However, just by looking at the data I think it's safe to say that this patch first of all doesn't seem to regress the current performance. Secondly it certainly looks *very* likely that this patch actually improves the performance, especially for the one-glyph-per-text-div case (cf. issue 7224).
Re: issue 7584.
This patch avoids having to calculate the scale twice by saving it in
the properties object.
Moreover, we remove a temporary variable and place parentheses around a
calculation inside a string concatenation.
This patch improves performance by avoiding unnecessary type
conversions, which also help the JIT for optimizations.
Moreover, this patch fixes issues with the div expansion code where
`textScale` would be undefined in a division. Because of the `dataset`
usage, other comparisons evaluated to `true` while `false` would have
been correct. This makes the expansion mode now work correctly for cases
with, for example, each glyph in one div.
The polyfill for `WeakMap` has been provided by @yurydelendik.
We pass many parameters to `appendText` while we might as well pass the
`task` object that contains them. This saves a few lines of code and
makes the signature of `appendText` more clear. We do the same for
`expand`, which is useful for the next commit in which we replace
`div.dataset` with a `WeakMap`.
Furthermore, this patch adds a missing parameter to a comment block to
make it clear which parameters remain.
1. Expanding divs to improve text selection. (Yury)
2. Adding enhanceTextSelection as an option.
3. Moving feature functionality from text_layer_builder.js to text_layer.js.
4. Added expandTextDivs method to only load expanded divs on first click, and only show on subsequent clicks
These have been found using `gulp lint` in combination with the `unused:
true` parameter for JSHint. Unfortunately there are too many false
positives to enable this feature, but now that most globals have been
removed because of the conversion to UMD the results are much more
useful than before.
