This supplements, rather than replaces, the existing caching in `PDFFunction.constructPostScript` since that one still makes sense given that functions are cached on the page-level.
Using an additional cache helps improve performance because:
- There are many fewer function calls, and overall less parsing this way.
- For the common case of `Uint8Array`-data we're able to use integer cache-keys, which is a lot faster than string concatenation.
This significantly improves performance of the `pr5134` test-case with `isEvalSupported = false` set, and testing locally in the viewer:
- With the `master` branch and `isEvalSupported = true`, page 2 renders in approx. 340 milliseconds.
- With the `master` branch and `isEvalSupported = false`, page 2 renders in approx. 1200 milliseconds.
- With this patch and `isEvalSupported = false`, page 2 renders in approx. 380 milliseconds.
While this is obviously still slower, the difference is now small enough that it shouldn't be too much of an issue in practice (compare with PR 18070) and the `pr5134` test-case is an especially "bad" one w.r.t. its PostScript function use.
For Type3 glyphs with `d1` operators it's easy to compute a fallback bounding box, however for `d0` the situation is more difficult.
Given that we nowadays compute the min/max of basic path-rendering operators on the worker-thread, we can utilize that by parsing these Type3 operatorLists to guess a more suitable fallback bounding box.
This addresses an inconsistency in the viewer, since the thumbnails don't respect the `maxCanvasPixels` option.
Note that, as far as I know, this has not lead to any bugs since the thumbnails render with a fixed (and small) width, however it really cannot hurt to address this (especially after the introduction of the `maxCanvasDim` option).
To support this a new `OutputScale`-method was added, to avoid having to duplicate code in multiple files.
One of the images have a corrupt SMask, where the /Height-entry is bogus; see the excerpt below (via https://brendandahl.github.io/pdf.js.utils/browser/).
```
SMask (stream) [id: 17, gen: 0]
ColorSpace = /DeviceGray
Height = /Length
Subtype = /Image
Filter = /FlateDecode
Type = /XObject
Width = 157
Matte (array)
BitsPerComponent = 8
Length = 3893
<view contents> download
```
Hence we enable SMask/Mask images to fallback to the parent image dimensions, and also add more validation of the width/height to get a better error message when that data is wrong.
These methods were introduced in *the first* commit of PR 4938, however they became unused in *the second* commit of that PR.
Hence it seems that we've been accidentally shipping, a small amount of, unused code for over a decade.
While initializing the `padded` Uint8Arrays we're manually assigning zeros to some entries, which is completely unnecessary since that's the default value for a TypedArray, and instead we can just increment the index.
When creating the `StyleMapping` for the "xfa-font-horizontal-scale" and "xfa-font-vertical-scale" properties there's currently pointless `Math.min` usage, since we're not actually comparing with anything.
When zooming, we should skip rendering the detail canvas until the
zoom is done, similarly to how normal page rendering is delayed.
To do so is enough to skip details view while zooming, since the
main view rendering that already happens after the delay will also
trigger rendering of the detail views.
This combines the `PDFFunctionFactory.create` and `PDFFunctionFactory.createFromArray` methods, which helps simplify and shorten the code.
Additionally, to simplify the parameter handling we pass the `PDFFunctionFactory`-instance directly to the various `PDFFunction`-methods.
This may not be possible to trigger in practice, however it seems that if `StampAnnotation.prototype.mustBeViewedWhenEditing` is called back-to-back with `isEditing === true` set then the second invocation could overwrite the `#savedHasOwnCanvas`-field and thus lose its initial state.
Currently we have a number of spots in the code-base where we need to clamp a value to a [min, max] range. This is either implemented using `Math.min`/`Math.max` or with a local helper function, which leads to some unnecessary duplication.
Hence this patch adds and re-uses a single helper function for this, which we'll hopefully be able to remove in the future once https://github.com/tc39/proposal-math-clamp/ becomes generally available.
With the changes in PR 19564 the actual `ColorSpace`-classes where separated from the various static "helper" methods.
Hence it seems that we can now simplify/shorten this old code to instead cache the "standard" ColorSpaces directly on the `ColorSpaceUtils`-class.
This patch reduces the number of `ColorSpaceUtils` static-methods, and in particular the `parseAsync` method is removed and it's now instead possible to have `parse` optionally return a Promise.
This thus removes the need to manually check if a `ColorSpace`-instance is cached, note the changes in the `src/core/evaluator.js` file.
