Centre wrapped text

A how-to guide: centre a wrapped display string — a masthead’s description, a title — so it breaks into even lines rather than a full first line and an orphan.

from sextile import (
    Align, Lines, OnOneFrame, Page, PageLayout, PageRequest, PageRouter, Sextile,
)
from sextile.viewdata.wrapping import Breaking, wrap_within

router = PageRouter()

_DESCRIPTION = "Local development board for the Content Provider API"


@router.page("1", name="board", title="The board")
async def board(request: PageRequest) -> Page:
    lines = wrap_within(_DESCRIPTION, cells=39, rows=2, breaking=Breaking.DISPLAY)
    return PageLayout(parts=[OnOneFrame(Lines(lines, align=Align.CENTRE))]).build(request)


app = Sextile(name="Directory", pages=[*router])

 THE BOARD                            1a
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      Local development board for       
        the Content Provider API        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
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 0 index                                

wrap_within(..., breaking=Breaking.DISPLAY) counts the last line’s slack, so a short string breaks into two even lines; Lines(lines, align=Align.CENTRE) then centres each. Left it to the default Breaking.PARAGRAPH and the same string fills the first line and strands the second — right for body text, where a final short line is expected, but top-heavy once centred.

Why the two are separate: breaking chooses where the lines end (sextile.viewdata.wrapping), alignment chooses where each line sits (a Lines part, computed at draw time). align takes the same Align — START, CENTRE, END — that Compose a frame and a Tile place with, one enum for placing anything across the frame. Body text stays left; the breaking and alignment terms are in Glossary.