# colitur-x

A raw Xlib front-end for [colitur](../colitur): reads `colitur emit --format
csv` on stdin, draws the year as a month grid coloured by each day's
liturgical colour, and shows the selected day's readings underneath.

    make && make install          # into ~/.local/bin
    colitur emit --format csv --from 2027 --to 2027 | colitur-x

Keys: arrows or `hjkl` move, `n`/`p` change month, `q` quits.

It opens on **today** when the input covers it. Reading the clock is a
presentation choice and belongs in a viewer: colitur's own kernel is pure
and deliberately never asks what day it is, which is what lets it be tested
to the year 9999.

    CX_DUMP=/tmp/f.ppm colitur-x < day.csv   # write one frame, then exit

It reads CSV on **stdin** and nothing else, so the shell decides what it
shows. One month:

    colitur emit --format csv --from 2027 --to 2027 | grep "^2027-04" | colitur-x

The header line is detected rather than assumed, so filtering it away is
fine. An earlier version skipped the first line unconditionally, which meant
that pipeline silently dropped 1 April -- the program fought the obvious
filter instead of composing with it.

Another language, or a local calendar:

    colitur emit --format csv --from 2027 --to 2027 --lang en | colitur-x
    colitur emit --format csv --from 2027 --to 2027 \
      --overlay ~/parish.sexp | colitur-x

With no input it says so and exits 2.

## Why it exists

colitur is a Unix tool: it computes and prints. This is a separate program
that composes with it, so colitur's own dependencies stay frozen
(`dune alcotest qcheck qcheck-alcotest sexplib ppx_sexp_conv`) and its
kernel stays pure.

## Build

    make

`-std=c99 -Os -Wall -Wextra`, linking libX11 and libXft. ~17 KB.

Configuration is compile-time, suckless style: edit `config.h` and rebuild.
There is deliberately no runtime config file — colitur itself owns the
calendar's configuration (language, sigla, overlays); this program owns only
how it is painted.

## Limits, stated rather than discovered

- X11 only. Runs under XWayland but is not a Wayland client.
- Read-only. It renders what colitur emits; it edits nothing.
- Xft is used for antialiasing and UTF-8. Dropping it for core X11 fonts
  would reduce the dependency list to libX11 and libc alone, at the cost of
  correct rendering for `æ`/`œ` and Polish diacritics. Not worth it.
- A tiling window manager will ignore the size hints and give the grid its
  own tile; the layout handles that, the empty space is the WM's choice.

## colitur-mu — the microui variant

`colitur-mu` is the same idea with an *editable* surface: year, language,
book-name form and numbering tradition are buttons, and changing any of them
re-runs colitur and reloads. It reimplements no calendar logic — every value
on screen came out of `colitur emit --format csv`, and the exact command is
shown in the status line.

    make colitur-mu && ./colitur-mu

microui (MIT, rxi) is **vendored** in `vendor/`, 1504 lines. That is the point:
a copied-in dependency cannot rot. `mu_x11.c` is the Xlib/Xft backend, ~150
lines — microui emits a command list and asks two font-metric questions; this
answers them.

### One bug worth recording

microui resets its scissor by emitting an "unclipped" rectangle of
`0x1000000` × `0x1000000`. `XRectangle`'s width and height are **unsigned
short**, so that truncates to **0** — turning "clip nothing" into "clip
everything". The symptom is that a scrolling panel draws its first screenful
and everything after it silently disappears, which looks like a layout or
buffer-overflow bug and is neither. `set_clip()` clamps to the buffer bounds
before converting.

### Verifying a frame without a screenshot

    MUX_DUMP=/tmp/frame.ppm ./colitur-mu     # writes one frame, then exits
    convert /tmp/frame.ppm /tmp/frame.png

This reads back the off-screen PIXMAP, not the window. A window's contents
are not retained while it is obscured or sitting on an unfocused tag, so
`import`/`xwd` against one can return solid black while the program is
drawing perfectly -- which cost real time to work out once. A pixmap is
always there.

### Which to use

`colitur-x` renders; `colitur-mu` renders and lets you change the invocation.
Neither is the right answer for a non-technical user on a machine that is not
yours — both are X11-only and must be compiled. For that, a static site or a
small local web UI wins.