The rest of FR-DSP-8. The develop session now carries the space its
canvas is encoded into, and `render` composes for it instead of for
sRGB — which is the whole of the change to the pixel path, because the
output space was always a parameter of composition and always entered
the structure hash. A display change is a recomposition.
The space is set on the way into every render rather than pushed when
the window moves, so a photograph opened while the window already sits
on the second monitor is right on its first frame instead of flashing
the wrong colour until the next poll.
Which display that is comes from sampling the window's position and
scale factor twice a second — Slint reports neither a move nor a
display change — and re-surveying only when they differ. Settings shows
what came back under ABOUT: the display, the space, why, and the other
monitors, because the failure FR-DSP-8 names is one that is invisible
from the display you are reading the page on.
Fractional scaling: the canvas is now rendered at the physical pixel
size of the box it occupies rather than the logical one, so the
compositor presents it 1:1. At 1.25 it was previously handed 1600
samples to fill 2000 device pixels, and the softness that produces
reads like a bad demosaic rather than like a scaling bug.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
FR-DSP-8's acquisition half. `dr_plat::display` surveys the session's
displays and reduces each one's profile to an output space the pipeline
can encode into, stating the mechanism per display server as
FR-PLAT-LIN-2 requires:
- X11 reads the `_ICC_PROFILE` / `_ICC_PROFILE_<n>` root-window
properties, enumerating and numbering the outputs through RandR,
which also yields the rectangles a window move is measured against.
- Wayland binds `wp_color_manager_v1` and asks each `wl_output` for
its image description, accepting either an ICC profile on a file
descriptor or primaries stated as chromaticities.
- Where neither answers, sRGB is assumed and the reason travels with
it as data rather than into a log, so the About page can say which
path the session is on.
A display profile is a measurement of one panel and is none of the four
spaces the pipeline knows. Rather than grow an ICC engine, the profile
is reduced to D50-adapted colorants and matched against the four; a
match that is merely nearest is marked as such and shown as such.
Verified on this machine: mutter 50 advertises the colour-management
global and reports eDP-1 as sRGB, and the same session forced onto X11
enumerates the output through RandR and correctly finds no atom.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
dtourolleandClaude Opus 5