G5: lapis, 0x4200.cafe's manuscript, as a theme with its ornament

A native theme `lapis` (src/themes/lapis.zig) from web/theme/lapis.css:
a lapis-deep page, lapis tags with gold names, vellum text, vermilion
rubrics, gold rules and a vermilion tag rule, gold selection in lapis ink.
Its ornament is the theme's new `decor` (colors.Decor), drawn by a pixel
shell inside the chrome it already has (decision 1), all of it off every
focus indicator:

- page_dots: the site's gold dot grid (#e8c46a22, 22 px), drawn by the
  cell shader on page-coloured cells alone (flag 0x10000000), so it lies
  under the text and never under a selection, a tag or the cursor; fixed
  to the window, a page the panes lie on.
- rail_checker: the dither frame's gold and lapis checker in the scroll
  track (a decor kind, flag 0x08000000), anchored to its rail; the thumb
  stays solid gold.
- tag plaques (tag_border, tag_shadow, tag_stripe): every tag a raised
  plaque inside its own band, the site's trail: a 2px gold frame and a
  hard 5px vermilion shadow down and right, both within the band's rows
  and columns (down, what the slack under the text leaves), so no shadow
  reaches a body, a grip or the next pane. The focused pane's plaque is
  the code window's title bar, gold and lapis stripes of 2px, its words
  on plates of the focused ground; unfocused ones are plain; column and
  workspace tags take the object-label language (1px frame, 2px shadow
  toward the page). Drawn as decor under the cells (a group's under
  range), with blank tag cells see-through and the cells blended
  premultiplied (pipeline_over) on such frames; opaque windows only.
- title_shadow: the titles' vermilion offset shadow under a file name's
  letters, sampled in the cell shader inside the letters' own cells (flag
  0x08000000), none on a cursor.

Chrome carries the decor (decor_*, name_ink, active_name_ink); a theme
file folds a nested decor literal field by field. Left out, with why, in
docs/effects.md: the fonts, the ornaments, a decor crossfade, and in the
tty anything but the colours (a tag row has no spare cell for a shadow).
An empty column is the page. The effect id is masked to 27 bits (ui.vert/ui.frag) for the
fifth flag.

Tests: the cell flags land only on page ground and file-name cells, never
a cursor, nothing without decor; lapis's plaques stay inside their tag's
band, clear of every grip, only the focused one striped; its checker is in
the track; no other theme draws any; the separator and focus
tests cover lapis. Goldens: theme and themesel (the ring gains lapis after
acme). Gates as G4. Feel review: .scratch/render/lapis/ (lapis.png, lapis-2x.png,
tags-focused-vs-unfocused-2x.png, a PanelSlide at 60 fps and a quarter).

1 files changed, 20 insertions, 0 deletions

diff --git a/src/surface.zig b/src/surface.zig
index 523cba43..5b850a8b 100644
--- a/src/surface.zig
+++ b/src/surface.zig
@@ -428,6 +428,26 @@ pub const Chrome = struct {
     /// The scroll column's width, button and scrollbar alike, in pixels at
     /// a 17px tagline (acme's 12 at its font); a pixel shell scales it.
     rail_px: u8 = 12,
+    /// The theme's ornament (colors.Decor), a pixel shell's alone: the dot
+    /// grid on the page, the scroll track's checker, the tags' plaques
+    /// (frame, shadow, the focused one's stripes) and the file name's shadow, each null when the theme has none, sizes
+    /// in logical pixels. `name_ink` and `active_name_ink` are the file
+    /// name's colours in a tag, which the shadow goes under.
+    decor_dots: ?[3]u8 = null,
+    decor_dot_alpha: u8 = 0,
+    decor_dot_px: u8 = 22,
+    decor_checker: ?[3]u8 = null,
+    decor_checker_px: u8 = 3,
+    decor_box_border: ?[3]u8 = null,
+    decor_box_border_px: u8 = 2,
+    decor_box_shadow: ?[3]u8 = null,
+    decor_box_shadow_px: u8 = 5,
+    decor_box_stripe: ?[3]u8 = null,
+    decor_box_stripe_px: u8 = 2,
+    decor_title: ?[3]u8 = null,
+    decor_title_px: u8 = 2,
+    name_ink: [3]u8 = .{ 0, 0, 0 },
+    active_name_ink: [3]u8 = .{ 0, 0, 0 },
 };
 
 /// The canonical interface: what a frame of pardes IS. The tty shell writes