init

pub fn init(grid: *GridWidget, init_opts: VirtualScroller.InitOpts) VirtualScroller {
        const si = init_opts.scroll_info;
        const total_rows_f: f32 = @floatFromInt(init_opts.total_rows);
        si.virtual_size.h = @max(total_rows_f * grid.row_height + scrollbar_padding_defaults.h, si.viewport.h);

        return .{
            .grid = grid,
            .si = si,
            .total_rows = init_opts.total_rows,
        };
    }