The cache has been added in #3312 in 2013 and a lot of things changed since.
Having too many cached accelerated canvases can lead to have to move their data from the GPU to the RAM
which is costly.
So this patch:
- removes all the cached canvases;
- destroys the useless canvases in order to free their associated memory asap;
- slightly rewrite canvas.js::_scaleImage to avoid too much canvas creation.
This code already isn't used (or even bundled) in the Firefox PDF Viewer, and it also slightly reduces the number of import maps that need to be maintained.
Currently we have no less than three different, but very similar, factories for reading built-in CMap files, standard font files, and wasm files on the main-thread.[1]
These factories were added at different points in time, since I cannot imagine that we'd add essentially three copies of the same code otherwise.
Nowadays these factories are often not even used[2], since worker-thread fetching is used whenever possible to improve performance. In particular, they will *only* be used when either:
- The PDF.js library runs in Node.js environments.
- The user manually sets `useWorkerFetch = false` when calling `getDocument`.
- The user provides custom `CMapReaderFactory`, `StandardFontDataFactory`, and/or `WasmFactory` instances when calling `getDocument`.
By replacing these factories with *a single* new `BinaryDataFactory` factory/option the number of `getDocument` options are thus reduced, which cannot hurt.
This also reduces the total bundle-size of the Firefox PDF Viewer a little bit, and it slightly reduces the number of import maps that need to be maintained.
*Please note:* For users that provide custom `CMapReaderFactory`, `StandardFontDataFactory`, and `WasmFactory` instances when calling `getDocument` this will be a breaking change, however it's unlikely that (many) such users exist.
(The *internal* format data-format of `CMapReaderFactory` was changed in PR 18951, and there hasn't been a single question/complaint about it in well over a year.)
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[1] Any new functionality could easily lead to more such factories being added in the future, which wouldn't be great.
[2] Note that the Firefox PDF Viewer no longer use these factories, since it "forcibly" sets `useWorkerFetch = true` during building.
Trying to resolve the same `objId` more than once would be a bug elsewhere in the code-base, since that should never happen, hence update the `resolve` method to prevent that.
The `BaseCMapReaderFactory`, `BaseStandardFontDataFactory`, and `BaseWasmFactory` classes are all very similar, and the only difference is really in their respective `fetch` methods.
By have the worker-thread "compute" the complete `filename` it's possible to simplify the `BaseCMapReaderFactory.prototype.fetch` method, which will allow future improvements to all of these classes.
A couple of things to note:
- This code is unused, and it's not even bundled, in the Firefox PDF Viewer.
- In browsers it's unused by default, and worker-thread fetching will always be used when possible since that's more efficient.
*Please note:* For users that provide a custom `CMapReaderFactory` instance when calling `getDocument` this could be a breaking change, however it's unlikely that any such users exist.
(The *internal* format of this data was changed previously in PR 18951, and there hasn't been a single question/complaint about it in well over a year.)
The WebGPU feature hasn't been released yet but it's interesting to see how
we can use it in order to speed up the rendering of some objects.
This patch allows to render mesh patterns using WebGPU.
I didn't see any significant performance improvement on my machine (mac M2)
but it may be different on other platforms.
Given that we "forcibly" set `useWorkerFetch = true` for the MOZCENTRAL build-target there's a small amount of dead code as a result, which we can thus remove during building.
Given that these classes are only used from the "FetchBinaryData" message handler, the `name`/`filename` parameters should never actually be missing and if they are that's a bug elsewhere in the code-base.
Furthermore a missing `name`/`filename` parameter would result in a "nonsense" URL and the actual data fetching would then fail instead, hence keeping this old validation code just doesn't seem necessary.
In PR 20367 the `CompiledFont.prototype.getPathJs` method was changed to return TypedArray data, however the `NOOP` fallback was (likely accidentally) left an empty string.
The compilation of font-paths in PR 20346 was then implemented such that an empty string just happened to be ignored silently, however the assert added in PR 20894 allowed me to spot this return value inconsistency.
*Please note:* Since this only applies to missing or broken glyphs, that wouldn't be rendered anyway, this doesn't show up in reference tests.
Providing one of these parameters is necessary when calling `getDocument`, since otherwise there's nothing to actually load. However, we currently don't enforce that properly and if there's more than one of these parameters provided the behaviour isn't well defined.[1]
The new behaviour is thus, in order:
1. Use the `data` parameter, since the PDF is already available and no additional loading is necessary.
2. Use the `range` parameter, for custom PDF loading (e.g. the Firefox PDF Viewer).
3. Use the `url` parameter, and have the PDF.js library load the PDF with a suitable `networkStream`.
4. Throw an error, since there's no way to load the PDF.
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[1] E.g. if both `data` and `range` is provided, we'd load the document directly (since it's available) and also initialize a pointless `PDFDataTransportStream` instance.
