Namely, for CalGrayColorSpace, CalRGBColorSpace, LabColorSpace.
Fixes a crash rendering any page of Adobe's 5014.CIDFont_Spec.pdf
(which uses CalRGBColorSpace with an indirect dict: The dict is
object `92 0`, and many color spaces are inline objects referring
to it).
I didn't find example code for this and the AI assistant did very
poorly on this as well. So I had to write it all by myself!
It can be much more efficient I think, but I think the overall
shape is maybe roughly fine.
* SampledFunction now keeps the StreamObject it gets data from alive
(doesn't matter too much in practice, but does matter in the test,
where nothing else keeps the stream alive).
* If a sample is an integer, we would previously sample that value
twice and then divide by zero when interpolating. Make sure to
sample 1 unit apart.
* Compare array size to 3 and 4, not 4 and 5
* Fix literal typo in error message
Fixes crash processing 0000906.pdf from 0000.zip from the pdf/a dataset.
We did convert from the input space to linear space and then
to linear sRGB, but we forgot to re-apply gamma.
This uses the x^2.2 curve instead of the real sRGB curve for now.
CalRGBColorSpace::color() converts into a flat xyz space,
which already takes input whitepoint into account.
It shouldn't be taken into account again when converting from
the flat color space to D65.
https://adobe-type-tools.github.io/font-tech-notes/pdfs/T1_SPEC.pdf,
8.4 First Four Subrs Entries:
"""If Flex or hint replacement is used in a Type 1 font program, the
first four entries in the Subrs array in the Private dictionary must be
assigned charstrings that correspond to the following code sequences. If
neither Flex nor hint replacement is used in the font program, then this
requirement is removed, and the first Subrs entry may be a normal
charstring subroutine sequence. The first four Subrs entries contain:
Subrs entry number 0:
3 0 callothersubr pop pop setcurrentpoint return
"""
othersubr handler 0 gets three arguments:
* The flex height (the distance after which the bezier splines
are replaced with just straight lines)
* The current position after the flex
It pushes that position on the postscript stack, where predefined subr
handler number 0 then pops it from. It then passes it to
setcurrentpoint.
In theory, we now correctly do that setcurrentpoint call, which we
previously weren't.
In practice, that setcurrentpoint call always receives the last point of
the flex -- and our path api apparently gets confused when move_to() is
called on it when the current point is already at that same location.
So tweak the SetCurrentPoint handler to not set the current point on
the path if it's already the path's current point, with a FIXME to
figure out what exactly is happening in Gfx::Path.
No big behavior change if flex is used, but this is more correct if it
isn't.
(This only works because our `return` handler is empty, else we would
have to make the callothersubr handler start a call frame.)
https://adobe-type-tools.github.io/font-tech-notes/pdfs/T1_SPEC.pdf,
8.4 First Four Subrs Entries:
"""If Flex or hint replacement is used in a Type 1 font program, the
first four entries in the Subrs array in the Private dictionary must be
assigned charstrings that correspond to the following code sequences. If
neither Flex nor hint replacement is used in the font program, then this
requirement is removed, and the first Subrs entry may be a normal
charstring subroutine sequence. The first four Subrs entries contain:
[...]
Subrs entry number 1:
0 1 callothersubr return
Subrs entry number 2:
0 2 callothersubr return
"""
So subr entry numbers 1 and 2 just call othersubr 1 and and 2, which
means we can just move the handling code over.
No behavior change if flex is used, but more correct if it isn't.
(This only works because our `return` handler is empty, else we would
have to make the callothersubr handler start a call frame.)
Previously we assumed a default precision of 6, which made the printed
values quite odd in some cases.
This commit changes that default to print them with just enough
precision to produce the exact same float when roundtripped.
This commit adds some new tests that assert exact format outputs, which
have to be modified if we decide to change the default behaviour.
This is a subset of #21484: Type 2 CFFs never use the special subrs,
so stop doing them for type 2 at least for now.
Fixes an assert in 0000064.pdf in 0000.zip in the pdfa dataset
(a stack underflow because a subr is supposed to push a bunch of
stuff, but instead it ran one of the built-in routines instead of
the subr from the font file).
As discussed in #21484, this isn't right for type 1 CFFs either,
but just removing the code there regresses Tests/LibPDF/type1.pdf.
A slightly more involved thing is needed there; I added a FIXME
for that here.
Previously, an xref stream with a field with larger than 8 would
result in an undefined shift occurring. We now ensure that each field
width is a number and is less than or equal to 8.
Nothing in PDF 1.7 spec 8.2.1 Destinations mentions the page being
`null`, but it happens in 0000372.pdf (for the root outline element)
and in 0000776.pdf (for every outline element, which looks like a
bug in the generator maybe) of 0000.zip from the pdfa dataset.
Documents using them now show render-time diagnostics instead
of asserting that number of parameters passed to a color don't
match whatever number of channels the previously-set color space
had.
Fixes two asserts on the `-n 500` 0000.zip test set.
Same as other recent color spaces: Enough to make us not assert,
but not enough to actually produce color.
Fixes 2 asserts on the `-n 500` 0000.zip pdfa dataset.
0000101.pdf from 0000.zip from the pdfa dataset has /Height set to
an indirect object that contains an int.
Make that work, and make sure various other similar places getting
values of the image dict also resolve indirect references.
No intended behavior change.
It does have the effect that indirect object references now go down
the array path instead of the number path. They still fall over there,
but now that's easy to fix.
0000459.pdf in 0000.zip in the pdfa dataset contains this as the
very first object:
```
1 0 obj
<<
/Creator (Developer 2000)
/CreatorDate (
/Author (Oracle Reports)
/Producer (Oracle PDF driver)
/Title (2021_06_29 Tutoritzacions APTES.PDF)
>>
endobj
```
The `/CreatorDate` value string is unterminated.
Before, we'd assert when trying to check if the first object is
a linearization dict.
Now, we never read the first object (an error during the linearization
dict reading is treated as "file is not linearized") unless we try
to print the document's metadata -- and there we now show an error
instead of asserting.
