Fixes a crash on page 3 of 0000450.pdf of 0000.zip, where we previously
started interpreting the middle of an inline image content stream as
operators, since it contained `EI` in its pixel data.
Fixes these errors from `Meta/test_pdf.py path/to/0000`, with
0000 being 0000.zip from the PDF/A corpus in unzipped:
Malformed PDF file: Indexed color space lookup table doesn't
match size, in 4 files, on 8 pages, 73 times
path/to/0000/0000206.pdf 2 4 (2x) 5 (3x) 6 (4x)
path/to/0000/0000364.pdf 5 6
path/to/0000/0000918.pdf 5
path/to/0000/0000683.pdf 8
When upsampling e.g. the 4-bit value 0b1101 to 8-bit, we used to repeat
the value to fill the full 8-bits, e.g. 0b11011101. This maps RGB colors
to 8-bit nicely, but is the wrong thing to do for palette indices.
Stop doing this for palette indices.
Fixes "Indexed color space index out of range" for 11 files in the
PDF/A 0000.zip test set now that we correctly handle palette indices
as of the previous commit:
Malformed PDF file: Indexed color space lookup table doesn't match
size, in 4 files, on 8 pages, 73 times
path/to/0000/0000206.pdf 2 4 (2x) 5 (3x) 6 (4x)
path/to/0000/0000364.pdf 5 6
path/to/0000/0000918.pdf 5
path/to/0000/0000683.pdf 8
Previously, we were scaling palette indices from 0..(palette_size - 1)
to 0..255 before using them as index into the palette. Instead, do not
scale palette indices before using them as indices.
(Renderer::load_image() uses `component_value_decoders.empend(
.0f, 255.0f, dmin, dmax)`, so to get an identity mapping, we have to
return `0, 255` from IndexedColorSpace::default_decode()).
Fixes rendering of the gradient on page 5 of 0000277.pdf.
Gfx::ICC::Profile's current API takes bytes, so we need to do some
contortions for LAB values to go through.
This will probably become nicer once we implement all the backward
transforms in Gfx::ICC::Profile, but for now let's hack it in
on the LibPDF side.
Makes colors in 0000651.pdf looks good, especially on pages 1 and 7-12.
If one profile uses PCSXYZ and the other PCSLAB as connection space,
we now do the necessary XYZ/LAB conversion.
With this and the previous commits, we can now convert from profiles
that use PCSLAB with mAB, such as stress.jpeg from
https://littlecms.com/blog/2020/09/09/browser-check/ :
% Build/lagom/icc --name sRGB --reencode-to serenity-sRGB.icc
% Build/lagom/bin/image -o out.png \
--convert-to-color-profile serenity-sRGB.icc \
~/src/jpegfiles/stress.jpeg
Instead of recomputing the left index and the float amount in that
interval for each coordinate all the time, do it once when we
preprocess the input coordinates.
One line less, faster, and arguably easier to read.
No behavior change.
Using `min()` to guarantee the left index is never == `size() - 1`,
even for an interpolation value of 1.0, is less code, and arguably
easier to understand as well.
No behavior change.
Since all parents held a reference pointer to their children, and all
children held reference pointers to their parents, both objects would
never get free'd once the document was no longer being used.
Fixes ossfuzz-63833.
This method takes bytes as input and decompress everything to a
ByteBuffer. It uses two control codes (clear and end of data) as
described in the GIF, TIFF and PDF specifications.
Page 1 of 0000277.pdf does:
BT 22 0 0 22 59 28 Tm /TT2 1 Tf
(Presented at Photonics West OPTO, February 17, 2016) Tj ET
BT 32 0 0 32 269 426 Tm /TT1 1 Tf
(Robert W. Boyd) Tj ET
BT 22 0 0 22 253 357 Tm /TT2 1 Tf
(Department of Physics and) Tj ET
BT 22 0 0 22 105 326 Tm /TT2 1 Tf
(Max-Planck Centre for Extreme and Quantum Photonics) Tj ET
Every line begins a text operation, then updates the font matrix,
selects a font (TT2, TT1, TT2, TT1), draws some text and ends the text
operation.
`Tm` (which sets the font matrix) contains a scale, and uses that
to update the font size of the currently-active font (cf #20084).
But in this file, we `Tm` first and `Tf` (font selection) second,
so this updates the size of the old font. So when we pull it out
of the cache again on line 3, it would still have the old size
from the `Tm` on line 2.
(The whole text scaling logic in LibPDF imho needs a rethink; the
current approach also causes issues with zero-width glyphs which
currently lead to divisions by zero. But that's for another PR.)
Fixes another regression from c8510b58a3 (which I've accidentally
referred to by 2340e834cd in another commit).
SMasks are greyscale images that get used as alpha channel for a
different image.
JPEGs in PDFs are stored as streams with /DCTDecode filters, and
we have a separate code path for loading those in the PDF renderer.
That code path just calls our JPEG decoder, which creates bitmaps
with format BGRx8888.
So when we process an SMask for such a bitmap, we have to change
the bitmap's format to BGRA8888 in addition to setting alpha values
on all pixels.
Per 1.7 spec 3.8.1, there are multiple logical text string types:
* text strings
* ASCII strings
* byte strings
Text strings can be in UTF-16BE, PDFDocEncoding, or (since PDF 2.0)
UTF-8.
But byte strings shouldn't be converted but treated as binary
data.
This makes us no longer convert strings used for drawing page text.
TABLE 5.6 "Text-showing operators" lists the operands for text-showing
operators as just "string", not "text string" (even though these strings
confusingly are called "text strings" in the body text), so not doing
this there is correct (and matches other viewers).
We also no longer incorrectly convert strings used for cypto data
(such as passwords), if they start with an UTF-16BE or UTF-8 marker.
No behavior change for outlines and info dict entries.
https://pdfa.org/understanding-utf-8-in-pdf-2-0/ has a good overview of
this.
(ASCII strings only contain ASCII characters and behave the same
anyways.)
This is a hack: Ideally we'd have a CMYK Bitmap pixel format,
and we'd convert to rgb at blit time. Then we could also apply color
profiles (which for CMYK images are CMYK-based).
Also, the colors for our CMYK->RGB conversion are off for PDFs,
and we have distinct codepaths for this in Gfx::Color (for paths)
and JPEGs. So when we fix that, we'll have to fix it in two places.
But this doesn't require a lot of code and it's a huge visual
progression, so let's go with it for now.
The file wasn't quite decided if it wanted to sort by ascii value
or by case folding. Now it uses ascii value, thanks to vim's
`:'<,'>sort`.
No behavior change.
This is a very inefficient implementation: Every time a type 3 font
glyph is drawn, we parse its operator stream and execute all the
operators therein.
We'll want to instead cache the glyphs in bitmaps (at least in most
cases), like we do for other fonts. But it's a good first step, and
all the coordinate math seems to work in the files I've tested.
Good test files from pdfa dataset 0000.zip:
- 0000559.pdf page 1 (and 2): Has a non-default font matrix;
text appears mirrored if the font matrix isn't handled correctly
- 0000425.pdf, page 1: Draws several glyphs in a single run;
glyphs overlap if Renderer::render_type3_glyph() ignores the
passed-in point
- 0000211.pdf, any page: Uses type 3 glyphs for all text.
Good perf test (already "reasonably fast")
- 0000521.pdf, page 5 (or 7 or or 16): The little red flag in the
purple box is a type 3 font glyph, and it's colored (which in part
means the first operator is `d0`, while all the other documents above
use `d1`)
Type 3 font glyphs begin with either `d0` or `d1`. If we bail out
with an "unsupported" error on the very first operator in a glyph,
we'll never paint the glyph.
Just stub these out for now. We probably want to do more in here in
the future (see "TABLE 5.10 Type 3 font operators" in the 1.7 spec).
They are the first operator in a type 3 charproc.
Operator.h already knew about them, but we didn't manage to parse
them, since they're the only two operators that contain a digit.
It's a bit unfortunate that fonts need to know about the renderer,
but type 3 fonts contain PDF drawing operators, so it's necessary.
On the bright side, it makes it possible to pass fewer parameters
around and compute things locally as needed.
(As we implement more fonts, we'll probably want to create some
functions to do these computations in a central place, eventually.)
No behavior change.
/BaseFont is a required key for type 0, type 1, and truetype
font dictionaries, but not for type 3 font dictionaries.
This is mechanical; type 0 fonts don't even use this yet
(but probably should).
PDFFont::initialize() is now empty and could be removed,
but maybe we'll put stuff there again later, so I'm leaving
it around for a bit longer.
In the main page contents, /T0 might refer to a different font than
it might refer to in an XObject. So don't use the `Tf` argument as
font cache key. Instead, use the address of the font dictionary object.
Fixes false cache sharing, and also allows us to share cache entries
if the same font dict is referred to by two different names.
Fixes a regression from 2340e834cd (but keeps the speed-up intact).
It's less code, but it also fixes a bug: The implementation in
Filter.cpp used to use the previous byte as reference value, while
we're supposed to use the value of the previous channel as reference
(at least when a pixel is larger than one byte).
No behavior change.
Ideally, the PDF code would just call a function PNGLoader to do the
PNG unfiltering, but let's first try to make the implementations look
more similar.
