An image can take one data source per colour component
(MultipleDataSources, or `colorimage` with multi true). The PostScript
Language Reference (3rd ed., §4.10 "Images" and `image`/`colorimage` in
chapter 8) has the operator read the sources in turn, the same amount
from each. The reader drained each source on its own instead: when the
sources are procedures reading one file a row at a time, the first plane
took the rows of every component and the image came out in sheared
horizontal bands, as in #498.
- Data sources are read in turn by one reader, `read_sources`: a procedure
once a round, a file or string a row a round, until each plane is full or
its source ends. Single sources, procedure filters and masked images use
it too; a string source resumes where it left off.
- Tests (`tests_images.rs`, programs written from the reference):
procedures reading one file in the dictionary and `colorimage` operand
forms (fails without the fix), separate string sources, rows padded to a
byte at 1, 2, 4, 12 and 16 bits with an odd width (one and several
sources), Flate PNG predictors with every row filter at an odd width.
The import fuzz vocabulary has several sources reading one file and
sources of uneven lengths.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
bflatasticandClaude Opus 5.5
1d265951df