*This fixes a regression from commit c9a0955c9c, i.e. PR 7738.*
Currently if you quickly rotate a document at least *twice*,[1] such that rendering of a page hasn't finished for the first rotation before the last rotation is triggered, the `cssTransform` method can fail to update the page correctly leading to it looking temporarily distorted.
The reason why things break is that previously we stored the `viewport` on the canvas DOM element, meaning that when it was accessed in `cssTransform` is was guaranteed to point to the `viewport` of the `zoomLayer` canvas.
Generally you want to avoid storing data on DOM elements this way, and during the `PDFPageView` refactoring needed to support SVG rendering, the previous `viewport` was instead stored directly on `PDFPageView`.
However, the problem is first of all that the `paintedViewport` only stores the *last* `viewport` computed, and second of all that there're no guarantees that it actually applies to the current `zoomLayer` canvas.
If a document is rotated slowly enough that rendering finishes *before* the next rotation then this problem doesn't exist, but for sufficiently quick rotations rendering will be cancelled at least once and the `paintedViewport` could thus be bogus.
The solution for the above problems is to ensure that we track the correct `viewport` for each DOM element (canvas or svg),[2] which seemed easist to do with a `WeakMap`.[3]
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[1] I'm able to reproduce this using the `tracemonkey` file, but please note that for pages with few operations, i.e. that render very quickly, the effect may be hard to spot.
[2] One other possible solution that I briefly considered, was to wait until rendering finished before storing the current `viewport`. However, that would have caused issues with rotating a page before the *first* rendering operation had finished.
[3] This regression took me way longer to both figure out, and fix, than I'd like to admit :-)
Please see http://eslint.org/docs/rules/spaced-comment.
Note that the exceptions added for `line` comments are intended to still allow use of the old preprocessor without linting errors.
Also, I took the opportunity to improve the grammar slightly (w.r.t. capitalization and punctuation) for comments touched in the patch.
Using `else` after `return` is not necessary, and can often lead to unnecessarily cluttered code. By using the `no-else-return` rule in ESLint we can avoid this pattern, see http://eslint.org/docs/rules/no-else-return.
As mentioned on IRC yesterday, we currently throw even when rendering is `cancelled`, which is annoying when the devtools are active. Furthermore, since `cancelled` isn't really an error, rejecting the `PDFPageView_draw` promise seems somewhat strange in that case.
Modern browsers support styling radio buttons and checkboxes with CSS.
This makes the implementation much easier, and the fallback for older
browsers is still decent.
*Please note that most of the necessary code adjustments were made in PR 7890.*
ESLint has a number of advantageous properties, compared to JSHint. Among those are:
- The ability to find subtle bugs, thanks to more rules (e.g. PR 7881).
- Much more customizable in general, and many rules allow fine-tuned behaviour rather than the just the on/off rules in JSHint.
- Many more rules that can help developers avoid bugs, and a lot of rules that can be used to enforce a consistent coding style. The latter should be particularily useful for new contributors (and reduce the amount of stylistic review comments necessary).
- The ability to easily specify exactly what rules to use/not to use, as opposed to JSHint which has a default set. *Note:* in future JSHint version some of the rules we depend on will be removed, according to warnings in http://jshint.com/docs/options/, so we wouldn't be able to update without losing lint coverage.
- More easily disable one, or more, rules temporarily. In JSHint this requires using a numeric code, which isn't very user friendly, whereas in ESLint the rule name is simply used instead.
By default there's no rules enabled in ESLint, but there are some default rule sets available. However, to prevent linting failures if we update ESLint in the future, it seemed easier to just explicitly specify what rules we want.
Obviously this makes the ESLint config file somewhat bigger than the old JSHint config file, but given how rarely that one has been updated over the years I don't think that matters too much.
I've tried, to the best of my ability, to ensure that we enable the same rules for ESLint that we had for JSHint. Furthermore, I've also enabled a number of rules that seemed to make sense, both to catch possible errors *and* various style guide violations.
Despite the ESLint README claiming that it's slower that JSHint, https://github.com/eslint/eslint#how-does-eslint-performance-compare-to-jshint, locally this patch actually reduces the runtime for `gulp` lint (by approximately 20-25%).
A couple of stylistic rules that would have been nice to enable, but where our code currently differs to much to make it feasible:
- `comma-dangle`, controls trailing commas in Objects and Arrays (among others).
- `object-curly-spacing`, controls spacing inside of Objects.
- `spaced-comment`, used to enforce spaces after `//` and `/*. (This is made difficult by the fact that there's still some usage of the old preprocessor left.)
Rules that I indend to look into possibly enabling in follow-ups, if it seems to make sense: `no-else-return`, `no-lonely-if`, `brace-style` with the `allowSingleLine` parameter removed.
Useful links:
- http://eslint.org/docs/user-guide/configuring
- http://eslint.org/docs/rules/
Ideally we'd remove the 'localized' event from the `eventBus`, but for backwards compatibility we keep it in `GENERIC` builds.
Note that while we want to ensure that the direction attribute of the HTML is updated as soon as the `localized` Promise is resolved, we purposely wait until the viewer has been initialized to ensure that the 'localized' event will always be dispatched.
With `bindEvents()` now being called after the viewer has been initialized, we no longer need to have `PDFViewerApplication.initialized` checks in the event handler functions.
Furthermore by moving the `window.addEventListener`s to a helper method, `PDFViewerApplication.initialized` checks are no longer necessary in the event handlers, hence we thus address part of issue 7797 here as well.
Note that in quick testing using `console.time/timeEnd`, both locally and with the Firefox addon, the total run time of the *entire* `PDFViewerApplication.initialize` function does not seem to change with this patch.
It seems that for normal web pages, at least in Firefox, the keyboard shortcuts <kbd>Ctrl</kbd> + <kbd>Up</kbd>/<kbd>Down</kbd> are functionally equivalent to <kbd>Home</kbd>/<kbd>End</kbd>. This is obviously an edge-case, but can be easily implemented by using the same logic as we do for <kbd>Home</kbd>/<kbd>End</kbd>.
Fixes 7852.
*Please note:* I'm finding it slightly difficult to interpret issue 7852, and bug 1285719, since among other things: the title includes the word "reverse" with no other mention of it, and the STR makes reference to print preview which doesn't seem applicable to the PDF viewer.
However, compared to regular web pages in Firefox, I think the behavior of this patch makes sense here.
This patch moves the user agent checks to the top of the file to reduce
duplication and to provide a clear overview of which user agent we are
detecting.
Moreover, we extract inline user agent checks as well and use existing
checks in more places. Finally, we fix the indenting in one place for
consistency.
For consistency, I also renamed the `FIREFOX/MOZCENTRAL` sessionStorage key, but given that sessionStorage is a lot less permanent than localStorage it didn't seem necessary to migrate any existing values.
Fixes 7760.
Currently if you try to enable SVG rendering in the addons, a `TypeError` is thrown by the browser since we have code that depends on what `paintOnCanvas`/`paintOnSvg` (should) return.
According to e.g. issue 7754, it appears that the current `isSafari` check is failing in newer version of the browser. Despite the fact that checking the userAgent is an anti-pattern, which should be avoided, it's currently the simplest solution.
Given that the `customScaleOption` should already be hidden, provided that the browser supports that, this patch also prevents it from being accessible via the keyboard.
As far as my testing goes in various browsers, this doesn't seem to have any ill effects, and note that we're already explicitly ignoring the `custom` value in the `select` event handler.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1315608.
This patch resolves the responsiveness issues for the toolbar in the
viewer. Depending on the language (for example the Dutch language),
elements could overlap when the viewport size is reduced.
The main issue here is that the CSS rules are unnecessarily complex and
handle lots of different cases (LTR/RTL, displacements for specific
viewport widths, et cetera). By removing this complexity and letting the
browser handle the responsiveness, we not only get simpler CSS rules and
HTML mark-up, but the responsiveness issues are mostly fixed at the same
time. We no longer have to position the elements manually (by setting
their `left` attribute value) anymore.
- Renamed startPrint to performPrint to emphasize that the method
does not start the print process (preparing pages for the printer),
but that it does the actual printing (sending pages off to the
printer).
- Put performPrint in the PDFPrintService, so that it can be
overridden if needed.
- Move the global scratchCanvas to PDFPrintService. This is mainly to
make it easier to reason about the state of scratchCanvas. In practice
there is no difference because only one PDFPrintService instance can
be instantiated at any given time.
- Move all logic of using the rendered page to one location.
This makes it easier to replace the printing logic later, when I add
special handling to out-of-process frames in the Chrome extension.
