layouts.py

"""
A layout is a list of regions expressed as fractions of the canvas
(x, y, w, h, each 0..1) — fractions rather than pixels so the same layout
name works whether it's being applied to a 250x122 strip or an 800x480
panel. Which layouts make sense for a given device is a judgment call the
dashboard author makes (a tiny mono strip probably shouldn't use grid-4),
not something this module tries to enforce.
"""

LAYOUTS = {
    "full": [
        (0.0, 0.0, 1.0, 1.0),
    ],
    "split-2h": [  # stacked, top/bottom
        (0.0, 0.0, 1.0, 0.5),
        (0.0, 0.5, 1.0, 0.5),
    ],
    "split-2v": [  # side by side
        (0.0, 0.0, 0.5, 1.0),
        (0.5, 0.0, 0.5, 1.0),
    ],
    "grid-4": [
        (0.0, 0.0, 0.5, 0.5),
        (0.5, 0.0, 0.5, 0.5),
        (0.0, 0.5, 0.5, 0.5),
        (0.5, 0.5, 0.5, 0.5),
    ],
}


def regions_for(layout_name: str, width: int, height: int) -> list[tuple[int, int, int, int]]:
    """Returns absolute pixel regions as (x, y, w, h) for the given canvas size."""
    fractions = LAYOUTS.get(layout_name)
    if fractions is None:
        raise ValueError(f"Unknown layout: {layout_name}")

    regions = []
    for fx, fy, fw, fh in fractions:
        x = round(fx * width)
        y = round(fy * height)
        w = round(fw * width)
        h = round(fh * height)
        regions.append((x, y, w, h))
    return regions