After the changes in PR 15812 we'll now *intermittently* display completely black canvases during zooming. To reproduce this, try switching to wrapped-scrolling and zoom in/out very quickly using either the mouse-wheel or pinching.
Note how in the API we're transferring the PDF data that's fetched over the network[1]:
- f28bf23a31/src/display/api.js (L2467-L2480)
- f28bf23a31/src/display/api.js (L2553-L2564)
To support that functionality we have the `PDFDataTransportStream`, `PDFFetchStream`, `PDFNetworkStream`, and `PDFNodeStream` implementations. Here these stream-implementations vary slightly in how they handle `ArrayBuffer`s internally, w.r.t. transferring or copying the data:
- In `PDFDataTransportStream` we optionally, after PR 15908, allow transferring of the PDF data as provided externally (used e.g. in the Firefox PDF Viewer).
- In `PDFFetchStream` we're currenly always copying the PDF data returned by the Fetch API, which seems unnecessary. As discussed in PR 15908, it'd seem very weird if this sort of browser API didn't allow transferring of the returned data.
- In `PDFNetworkStream` we're already, since many years, transferring the PDF data returned by the `XMLHttpRequest` functionality. Note how the `getArrayBuffer` helper function simply returns an `ArrayBuffer` response as-is.
- In `PDFNodeStream` we're currently copying the PDF data, however this is unfortunately necessary since Node.js returns data as a `Buffer` object[2].
Given that the `PDFNetworkStream` has been, indirectly, supporting transferring of PDF data for years it would seem really strange if this didn't also apply to the `PDFFetchStream`-implementation.
Hence this patch simply enables transferring of PDF data, when accessed using the Fetch API, unconditionally to help reduced main-thread memory usage since the `PDFFetchStream`-implementation is used *by default* in browsers (for the GENERIC build).
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[1] As opposed to PDF data being provided as e.g. a TypedArray when calling `getDocument` in the API.
[2] This is a "special" Node.js object, see https://nodejs.org/api/buffer.html#buffer, which doesn't exist in browsers.
- Scale factor is rounded to only scale by integer percent, hence the unused
ticks are accumulated (like we already do for zoom with the mouse wheel).
- Use the same thing for the pinch-to-zoom on a touchscreen: it led to slightly
refactor the code because it happened to ignore a not so small scale which
led to a not so smooth zooming.
Also, removes the `initialData`-parameter JSDocs for the `getDocument`-function given that this parameter has been completely unused since PR 8982 (over five years ago). Note that the `initialData`-parameter is, and always was, intended to be provided when initializing a `PDFDataRangeTransport`-instance.
Version 16 that we used before is now in maintenance mode, so we should
upgrade to the most recent LTS version. For more information on the
Node.js release schedule please refer to
https://github.com/nodejs/release#release-schedule.
After the changes in PR 15850, the `background-color` of the sidebar is now unnecessarily dark in the light-theme. Hence, we can simply remove this CSS rule to improve things overall (and these changes don't affect the dark-theme much at all).
This is even an overall consistency improvement, given the existing `--sidebar-narrow-bg-color` values.
Given that this is internal functionality, not exposed in the official API, it's not entirely clear (at least to me) why we can't just initialize this directly in `src/display/api.js` instead.
When testing both the development viewer and all the ways in which we run tests, everthing still appears to work just fine with this patch.
*Please note:* The reduced test-case is *not* a perfect reproduction of the original PDF document, since this one fails to open in e.g. Adobe Reader, but I do believe that it captures the most important points here.
For corrupt *and* encrypted PDF documents, it's possible that only some trailer dictionaries actually contain an /Encrypt-entry. Previously we'd could easily miss that, since we generally pick the first not obviously corrupt trailer dictionary, and the solution implemented here is to simply pre-parse all trailer dictionaries to see if there's any /Encrypt-entries.
In most of the cases, showing the loading icon is useless because
it's for a very short time, consequently it doesn't bring any useful
information for the user.
After a delay (400ms), the icon is shown in order to inform the user
that the viewer isn't stuck but it's doing something.
In GeckoView, on an event, a callback must be executed with the result of an action,
but the callback can be used only one time.
So for each FindInPage event, we must trigger only one matches count update.
