Macro grid_layout_const_var 

macro_rules! grid_layout_const_var {
    ($name:ident, $base_idx:expr, ($x:expr, $y:expr, $width:expr, $height:expr),
    ($rows:expr, $cols:expr, $gap:expr), [$first:ident, $($rest:ident),+ $(,)?], $layout_fn:ident, $suffix:ident) => { ... };
}

Creates constant variables for a grid layout.

This macro generates:

• A constant for the layout area
• A constant for the grid layout array
• Constants for each region in the grid

Arguments

• name - The base name for the generated constants and enum
• base_idx - The base index to use for region constants
• (x, y, width, height) - The area for the grid layout
• (rows, cols, gap) - The grid dimensions and gap
• [first, rest...] - The region names
• layout_fn - The layout function to use (column or row)
• suffix - The suffix to use for the layout array constant