This disallowd the following types of `export` declaration:
- `export class A {}`/`export function A() {}`
- `export default class A {}`/`export default function A() {}`
- `export let A`/`export const A`/`export var A`
While allowing
- `export { A }`
- `export default A`
The current text layer approach based on absolutely positioned
`<span>` elements by default causes flickering with text selection,
and we have browser-specific workarounds to solve that.
In Chrome, the workaround involves moving the `.endOfContent` element to
right after the last element that contains some selected content. This
works well in simple PDFs, but breaks when we have `span.markedContent`
elements. Given a text layer structure like the following, rendered
as four consecutive lines:
```html
<span class="markedContent">
<br>
<span>development enter the construction phase (estimated at around</span>
</span>
<span class="markedContent">
<br>
<span>300 MEUR).</span>
</span>
<span class="markedContent">
<br>
<span>Kreate's EBITA increased to 2.8 MEUR (Q4'23: 2.7 MEUR) and the</span>
</span>
<span class="markedContent">
<br>
<span>margin rose to 3.7% (Q4'23: 3.4%). However, profitability was</span>
</span>
```
when starting to select from inside the first line and dragging down
to the empty space after the second line, Chrome will anchor the
selection at the beginning of either the `<br>` or the `<span>` inside
the last `.markedContent`, depending on whether the selection is in
"per-character mode" (i.e. click and drag) or "per-word mode" (i.e.
double click and drag). This causes us to insert the `.endOfContent`
element in the wrong place (one element too far), which causes one
more line to be selected, which triggers another `"selecctionchange"`
event, which causes us to move `.endOfContent` again, and so on, looping
until when the whole page is selected.
This commit fixes the issue by making sure that when the end of the
selection range points to the _begining_ of an element, we walk back
the dom finding the first non-empty element, and attatch `.endOfContent`
to the end of that.
In order to use the PDF.js library in Node.js environments the `process.getBuiltinModule` functionality must be available, which was released in [version `20.16.0`](https://nodejs.org/en/blog/release/v20.16.0), however we've seen repeated issues filed by users on older `20.x` versions.
We want to iterate through the data in the `computeMD5` function, and `Map`s have "nicer" support for that than generic objects.
(Somewhat recently `Map` performance was improved in Firefox, however this also isn't really performance sensitive code.)
Note that we load all wasm-files manually, however the Emscripten Compiler (emcc) unfortunately generates `URL`s for fallback wasm-file loading.
In the PDF.js build-scripts we work-around that by using suitable Webpack-options, however that apparently doesn't work when third-party users re-bundle our code and we thus try to work-around this by adding "ignore comments" to these `URL`s (similar to how we handle `import`-statements).
It seems that the `@napi-rs/canvas` dependency has *basic* canvas-filter support, whereas the "old" `canvas` dependency didn't, hence we no longer need the Node.js-specific checks in the `src/display/canvas.js` file.
Note that I've successfully tested the [`pdf2png` example](https://github.com/mozilla/pdf.js/tree/master/examples/node/pdf2png) with this patch applied and things appear to work as before.
After PR 19731 the format of compiled Type3-glyphs is now simple enough that the compilation can be moved to the worker-thread, without introducing any significant additional complexity.
This allows us to, ever so slightly, simplify the implementation in `src/display/canvas.js` since the Type3 operatorLists will now directly include standard path-rendering operators (using the format introduced in PR 19689).
As part of these changes we also stop caching Type3 image masks since: we've not come across any cases where that actually helps, they're usually fairly small, and it simplifies the code.
Note that one "negative" change introduced in this patch is that we'll now compile Type3-glyphs *eagerly*, whereas previously we'd only do that lazily upon their first use.
However, this doesn't seem to impact performance in any noticeable way since the compilation is fast enough (way below 1 ms/glyph in my testing) and Type3-fonts are also limited to just 256 glyphs. Also, many (or most?) Type3-fonts don't even use image masks and are thus not affected by these changes.
In using the Firefox profiler (with JS allocations tracking) and wuppertal.pdf, I noticed
we were using a bit too much memory for a function which is supposed to just compute 2 numbers.
The memory used by itself isn't so important but having a too much objects lead to waste some time
to gc them.
So this patch aims to simplify it a bit.
