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.
Make sure that the print service is stopped as soon as possible when
aborted, and that it is not possible for a (slow) promise to
accidentally wipe the state of a print job that was started later.
There's no mention of our `#{pagenum}` form in http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/pdf_open_parameters.pdf, and Adobe Reader doesn't seem to support it either.
Hence this patch removes support for it in the extensions, but keeps it in the `GENERIC` build with a deprecation warning and a fallback to handle it as a destination.
Fixes 7746.
This patch implements the page label functionality in a similar way as Adobe Reader.
For documents with page labels, if a non-existent page label is entered we'll try to fallback to the page number instead.
The patch also includes a preference (`disablePageLabels`), to make it easy to opt-out of using page labels if the user/implementor so wishes.
The way that `get/set currentPageLabel` is implemented in `PDFViewer`, is as wrappers for the corresponding `get/set currentPageNumber` functions, since that seemed like the cleanest solution.
The page labels are purposely *only* added to the page controls in the viewer UI, and not stored in e.g. the `ViewHistory`. Since doing so would mean adding unnecessary code complexity, without any real added value, and would also mean delaying the inital loading of PDF documents.
Note that this patch will ignore page labels if they are identical to standard page numbering, since in this case displaying the page labels adds no value (but only UI noise). The reason for handling this case specially, is that in practice a surprising number of PDF files include "pointless" page labels.
The following reasoning was used for deciding to remove the "Page: " label, and replace it with a tooltip, from the main toolbar:
- We have no other visible labels in the *main* toolbar (e.g. the Zoom dropdown doesn't have a label, but only a tooltip).
- We already hide the "Page: " label when the viewer is narrow.
- The varying width of the "Page: " label in different locales is already causing issues for many languages, with overlap in the main toolbar as a result.
Trying to create responsive CSS styles that works well in all locales is already difficult, and if we add support for page labels that will only further compound the issues.
- Some PDF viewers (e.g. Adobe Reader, pdfium in Chrome) doesn't show labels in the UI by default.
In some PDF files, the first element (i.e. the one containing either a `Ref` or a `Number` pointing to a page) of the explicit destination Array may be bogus.
One such example is actually the file `pdf.pdf` in the test-suite, where some destinations are incompletely specified. One such example being the `G1.998360` destination whose explicit destination Array contains `[null, /XYZ, 54, 488, null]`, i.e. the destination page is `null`.
Hence this patch adds a bit more validation for that case. It also adds an additional check to ensure that the resulting `pageNumber` is non-negative, and finally a couple more error messages for existing cases of malformed data.
Note that in `FIREFOX/MOZCENTRAL/CHROME` builds of the standard viewer the `docBaseUrl` parameter will be set by default, since in that case it makes sense to use the current URL as a base.
For the `GENERIC` viewer, or the API itself, it doesn't make sense to try and set the `docBaseUrl` by default. However, custom deployments/implementations may still find the parameter useful.
