Theming

Every AES widget is drawn from a theme — a bitmap atlas plus a table of named slices — rather than from hard-coded lines. The reference theme is derived from Cappuccino’s Aristo2, giving the desktop a modern Aqua-style look. Applications never reference the theme directly; they create AES objects and the theme is applied for them.

9-slice rendering

Almost every widget is a 9-slice (nine-patch): four fixed corners, four edges stretched along one axis, and a centre stretched both ways. A window, button, text field, scrollbar track and menu are all 9-slice (or its degenerate cases — a 3-slice strip, or a single sprite). Corners stay 1:1 at any size, so a button scales cleanly to any label width.

The renderer is theme_blit, which issues the nine sub-blits through vr_transfer_bits in its VR_OVER (per-pixel src-over alpha) mode — so the artwork’s anti-aliased edges and soft shadows composite correctly. theme_draw(name, rect) looks a slice up by name and blits it; that is the single call the AES uses to render a widget.

On-disk format

A theme lives in OS/Themes/<name>/<scale>/ (the <scale> directory leaves room for a @2x high-DPI set later):

• artwork.tex — a raw RGBA-8888 atlas (GTEX header + width/height + pixel rows). It is baked from PNGs ahead of time, so the target needs no PNG decoder at runtime; the atlas loads straight into an off-screen bitmap workstation.
• locations.txt — one line per slice: name x y w h l t r b fill, where x y w h is the slice’s rectangle in the atlas, l t r b the 9-slice insets, and fill is stretch / tile / none.
• theme.ini — the colours (fg, highlight, sel_bg, border, disabled), since those come from the theme’s descriptor, not the artwork.

Baking a theme

The host tool themepack builds the atlas from a recipe. Each recipe line names an element, a type, and its source PNGs:

window    nine    window-standard-top-left … window-standard-bottom-right
button    h3      button-bezel-left button-bezel-center button-bezel-right
close     sprite  window-standard-close-button

• Types — sprite (1 image), h3 (left / centre / right), v3 (top / centre / bottom), nine (the nine corners/edges/centre).
• The 9-slice insets are derived automatically from the corner slice sizes.
• A source token can carry a suffix: @90/180/270 rotates the slice (the vertical scrollbar reuses the date-picker arrows rotated), ~N trims N px from the centre of a strip (narrowing a track to its arrows), and ^RRGGBB colour-tints a slice (the blue default button is the grey bezel tinted).

themepack decodes the PNGs (via ImageMagick on the host), composes each element, packs them into one atlas, and writes the three files above. Adding a widget is a recipe line, not code.

Widget coverage

The reference theme covers: the window frame + titlebar (active / inactive) + traffic-light controls; push buttons (normal / default / pressed / disabled); checkboxes (off / on / mixed) and radio buttons; popups, combos and text fields (with focused / disabled states); menus + tick mark; sliders (horizontal / vertical / circular); scrollbars (both axes, track + thumb + arrows); steppers; the table header; and the alert icons.