Rather than modifying the "raw" dimensions of the page, we'll instead apply the `userUnit` as an *additional* scale-factor via CSS.
*Please note:* It's not clear to me if this solution is fully correct either, or if there's other problems with it, but it at least *appears* to work.
---
With these changes, the following CSS variables are now assumed to be available/set as necessary: `--total-scale-factor`, `--scale-factor`, `--user-unit`, `--scale-round-x`, and `--scale-round-y`.
I discovered that doing skip-cache re-reloading of https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf would *intermittently* cause (some of) the AnnotationLayers to break with errors printed in the console (see below).
In hindsight this bug is really obvious, however it took me quite some time to find it, since the `StructTreePage.prototype.serializable` getter will lookup various data and all of those cases can fail during loading when streaming and/or range requests are being used.
Finally, to prevent any future errors, ensure that the viewer won't break in these sort of situations.
```
Uncaught (in promise)
Object { message: "Missing data [19098296, 19098297)", name: "UnknownErrorException", details: "MissingDataException: Missing data [19098296, 19098297)", stack: "BaseExceptionClosure@resource://pdf.js/build/pdf.mjs:453:29\n@resource://pdf.js/build/pdf.mjs:456:2\n" }
viewer.mjs:8801:55
\#renderAnnotationLayer: "UnknownErrorException: Missing data [17552729, 17552730)". viewer.mjs:8737:15
Uncaught (in promise)
Object { message: "Missing data [17552729, 17552730)", name: "UnknownErrorException", details: "MissingDataException: Missing data [17552729, 17552730)", stack: "BaseExceptionClosure@resource://pdf.js/build/pdf.mjs:453:29\n@resource://pdf.js/build/pdf.mjs:456:2\n" }
viewer.mjs:8801:55
```
The idea is to insert a span in the text layer with an aria-role set to img
and use the bounding box provided by the attribute field in the tag dict in
order to have non-null dimensions for the image to make it "visible".
In hindsight it occurred to me that there's a couple of smaller issues with this method after it's made asynchronous (in PR 18658).
- If the `render`-method is invoked back-to-back the existing caching doesn't guarantee that re-parsing won't occur, which we can address by introducing a new (private) promise.
- If there's any errors fetching and/or parsing the structTree-data, we'd attempt to parse it again on re-rendering despite that being pointless.
Testing the `tagged_stamp.pdf` document locally in the viewer, I noticed that e.g. the /Alt entry for the StampAnnotation contains "Secondary text for stamp\u0000".
Elsewhere in the viewer we're skipping null-chars and it's easy enough to do that in the `StructTreeLayerBuilder` class as well. (Note that we generally let the API itself return the data as-is.)
Compared to the recent PR 15722 for the `textLayer` this one should be a (comparatively) much a smaller win overall, since most documents don't have any structTree-data and the required parsing should be cheaper. However, it seems to me that it cannot hurt to improve this nonetheless.
Note that by moving the `structTreeLayer` initialization we remove the need for the "textlayerrendered" event listener, which thus simplifies the code a little bit.
Also, removes the API-caching of the structTree-data since this was basically done to offset the lack of caching in the viewer.
This patch, first of all, removes circular dependencies in the TypeScript definitions. Secondly, it also moves `RenderingStates` into `web/ui_utils.js` to break another type-dependency and directly use the `XfaLayerBuilder` during XFA-printing.
Finally, note that this patch *slightly* reduces the size of the default viewer (e.g. in the `MOZCENTRAL` build) by not having to bundle code which is completely unused.
This patch circumvents the issues seen when trying to update TypeScript to version `4.5`, by "simply" fixing the broken/missing JSDocs and `typedef`s such that `gulp typestest` now passes.
As always, given that I don't really know anything about TypeScript, I cannot tell if this is a "correct" and/or proper way of doing things; we'll need TypeScript users to help out with testing!
*Please note:* I'm sorry about the size of this patch, but given how intertwined all of this unfortunately is it just didn't seem easy to split this into smaller parts.
However, one good thing about this TypeScript update is that it helped uncover a number of pre-existing bugs in our JSDocs comments.
The Viewer API definitions do not compile because of missing imports and
anonymous objects are typed as `Object`. These issues were not caught
during CI because the test project was not compiling anything from the
Viewer API.
As an example of the first problem:
```
/**
* @implements MyInterface
*/
export class MyClass {
...
}
```
will generate a broken definition that doesn’t import MyInterface:
```
/**
* @implements MyInterface
*/
export class MyClass implements MyInterface {
...
}
```
This can be fixed by adding a typedef jsdoc to specify the import:
```
/** @typedef {import("./otherFile").MyInterface} MyInterface */
```
See https://github.com/jsdoc/jsdoc/issues/1537 and
https://github.com/microsoft/TypeScript/issues/22160 for more details.
As an example of the second problem:
```
/**
* Gets the size of the specified page, converted from PDF units to inches.
* @param {Object} An Object containing the properties: {Array} `view`,
* {number} `userUnit`, and {number} `rotate`.
*/
function getPageSizeInches({ view, userUnit, rotate }) {
...
}
```
generates the broken definition:
```
function getPageSizeInches({ view, userUnit, rotate }: Object) {
...
}
```
The jsdoc should specify the type of each nested property:
```
/**
* Gets the size of the specified page, converted from PDF units to inches.
* @param {Object} options An object containing the properties: {Array} `view`,
* {number} `userUnit`, and {number} `rotate`.
* @param {number[]} options.view
* @param {number} options.userUnit
* @param {number} options.rotate
*/
```
When a PDF is "marked" we now generate a separate DOM that represents
the structure tree from the PDF. This DOM is inserted into the <canvas>
element and allows screen readers to walk the tree and have more
information about headings, images, links, etc. To link the structure
tree DOM (which is empty) to the text layer aria-owns is used. This
required modifying the text layer creation so that marked items are
now tracked.
