Many years ago now there were some `Promise` implementations that had issues resolving with an *implicitly* `undefined` value. That should no longer be the case, and we've not been using the `Promise.resolve(undefined)` format for a long time, hence this patch fixes the few remaining cases.
Having recently worked with this code, in PR 14096 (and indirectly in PR 14112), I happened to notice a pre-existing issue with spreadModes at higher zoom levels.
The `PDFRenderingQueue` code was written back when the viewer only supported "normal" vertical scrolling, and some edge-cases related to spreadModes are thus not perfectly supported. Depending on the zoom level, it's possible that there are "holes" in the currently visible page layout, and those pages will not be pre-rendered as you'd expect.
*Steps to reproduce:*
0. Open the viewer, e.g. https://mozilla.github.io/pdf.js/web/viewer.html
1. Enable vertical scrolling.
2. Enable the ODD spreadMode.
3. Scroll down, such that both pages 1 and 3 are visible.
4. Zoom-in until *only* page 1 and 3 are visible.
5. Open the devtools and, using the DOM Inspector, notice how page 2 is *not* being pre-rendered despite all surrounding pages being rendered.
If a PDF included an embedded TrueType font whose preferred character
map (cmap) was in "format 2", the code would select that character map
and then refuse to read it because of an unsupported format, thus
causing the characters not to be rendered. This commit implements
support for format 2 as described at the link below.
https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6cmap.html
With the previous commit, both of the `PDFViewer` and `PDFSinglePageViewer` clases are now small/simple enough that it no longer seems necessary to keep them in separate files.
This implements a new Page scrolling mode, essentially bringing (and extending) the functionality from `PDFSinglePageViewer` into the regular `PDFViewer`-class. Compared to `PDFSinglePageViewer`, which as its name suggests will only display one page at a time, in the `PDFViewer`-implementation this new Page scrolling mode also support spreadModes properly (somewhat similar to e.g. Adobe Reader).
Given the size and scope of these changes, I've tried to focus on implementing the basic functionality. Hence there's room for further clean-up and/or improvements, including e.g. simplifying the CSS/JS related to PresentationMode and implementing easier page-switching with the mouse-wheel/arrow-keys.
This patch (slightly) simplifies a couple of `onProgress` and `onUnsupportedFeature` call-sites.
Finally, while unrelated, also removes some unnecessary `return undefined;` statements (PR 11601 follow-up).
For Circle, Square, and Polygon Annotations it's currently only possible to toggle the associated PopupAnnotation by clicking on its border. Depending on the border width, and also the current zoom-level in the viewer, that can make interacting with certain Annotations *practically* impossible (which is the case in issue 14107).
Hence, in order to improve this, change the "fill"-property of the SVG element in the annotationLayer to make the *entire* element part of the click/mouse-over target.
*Please note:* Given that this is a viewer-related issue, there's no simple way to test this as far as I can tell.
This is unfortunately *yet another* bug in the `preEvaluateFont`-implementation, and I've lost count of the number of times I've had to tweak this code over the years :-(
I really cannot help thinking that PR 4423 was way too simplistic, since it missed a bunch of cases that leads to broken font rendering in many PDF documents.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1734802
- the exact sentence from the spec:
"The token SOLIDUS (a slash followed by no regular characters) introduces a unique valid name defined by the empty sequence of characters."
- so just remove the warning.
Note that PR 14049 removed this, since https://github.com/mozilla/pdf.js/pull/14049#discussion_r716245518 claimed that it's not necessary anymore. Unfortunately that, in my testing on Windows, actually re-introduced exactly the issue described in the comment; more specifically once the *last* character has been entered in the comb-field it's now again incorrectly scrolled (with the first character being invisible) until focus is lost.
This can be tested with e.g. `f1040.pdf`, see page 2, from the test-suite.
With a recent addition to the HTML specification, the internal structured clone algorithm used in browsers is (or will be, once it's implemented) *directly* accessible to JavaScript; please see https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/structuredClone
Hence we'll *eventually* not need to maintain our own structured clone functionality in the `LoopbackPort`-class in the API, however for the time being we'll feature detect `structuredClone` and fallback to the existing PDF.js implementation.
Given that https://bugzilla.mozilla.org/show_bug.cgi?id=1722576 has landed in Firefox 94, we should no longer need the manually implemented `cloneValue`-functionality in MOZCENTRAL builds. Note also that in the Firefox built-in PDF Viewer it's not possible for users to *easily* disable workers, which should further reduce the risk of these changes.
This patch helps reduce some duplication, given that we now have a few essentially identical `addLinkAttributes` call-sites in the code-base.
To prevent runtime errors in the Annotation/XFA-layer code, we'll warn if a custom/incomplete `PDFLinkService` is being used (limited to GENERIC builds).
Please note that we (obviously) don't want to unconditionally pre-render more than one page all the time, since that could very easily lead to overall worse performance in some documents.[1]
However, when spreadModes are enabled it does make sense to attempt to pre-render both of the pages of the next/previous spread.
---
[1] Since it may cause pre-rendering to unnecessarily compete for parsing resources, on the worker-thread, with "regular" rendering.
Note how both the annotationLayer and the document outline will apply various URL-related options when creating the link-elements.
For consistency the `xfaLayer`-rendering should obviously use the same options, to ensure that the existing options are indeed applied to all URLs regardless of where they originate.
Given that `NodeList`s can be iterated using `for..of` we can use that instead, since it's a little bit nicer and easier to read than the `Array.prototype.forEach` format.
