Patch 38 now also replaces the /ColorSpace of a shading that is
DeviceGray, DeviceRGB or DeviceCMYK with the default for it, whether the
shading is painted by sh or as a shading pattern. Poppler and MuPDF draw
these in the default too. The shading's cache key includes the default,
as the image's does.
The forms test also covers a form whose /ColorSpace has no default: it
draws in its page's, as in Poppler and MuPDF.
hayro-interpret cached the colour space built from an /ICCBased profile
stream under the hash of the stream's dictionary bytes alone. Two
different profiles with the same /N and /Length (any two uncompressed
RGB profiles of one size) shared whichever was read first, so colours in
the second space were drawn through the first profile for the rest of
the document. Found while fixing #1201.
The space is now keyed by what its profile is read from (IccProfileKey):
the stream object a space names, looked up without reading the stream,
and on a miss the old dictionary key plus the stream's own bytes
(decrypted, not decoded), so byte-for-byte copies in other objects still
share one parsed profile and a lookup never decodes. A stream written
directly in the colour space array reports the object holding the array,
as every other stream written there does; it is recognised by its
dictionary lying within the array's bytes and keyed by content only.
InterpreterCache::icc_profile_reads counts the profiles read, so the
tests can check that the cache still hits. Tests: two synthetic RGB
profiles of one length (linear sRGB, and red and blue swapped) as
objects, a reused object, a copy and direct streams on one page.
A resource dictionary's DefaultGray, DefaultRGB and DefaultCMYK colour
spaces replace the device space content selects (ISO 32000-2 §8.6.5.6).
hayro ignored them: g/G, rg/RG and k/K set the device space directly,
cs/CS resolved the device names before looking at the resources, and
images took their /ColorSpace as written. Pages that calibrate device
colour this way, common in PDF/A, came out in the wrong colours.
The interpreter now looks the defaults up once per content window
(DefaultColorSpaces), in the resources and those they inherit, so a form
XObject without its own draws in its page's. They replace DeviceGray,
DeviceRGB and DeviceCMYK selected by the colour operators, by cs/CS (by
name or through a /ColorSpace resource that is a device space), and as
the /ColorSpace of image XObjects and inline images. A default that is a
Lab, Indexed, Pattern or device space, has another number of components
or is not a colour space is ignored, and device colour is drawn as
before. Device spaces nested in other spaces, shading dictionaries,
masks and transparency group spaces are unchanged. The decoded-image
cache keys a decode by the default it was drawn in, since one image can
be drawn with and without one.
Part of #1201.
aiongg