Boxed banners

A how-to guide: set a word in a coloured box fitted round it, in whatever face it is given.

from sextile import Custom, OnOneFrame, Page, PageLayout, PageRequest, PageRouter, Sextile
from sextile.viewdata import lettering
from sextile.viewdata.canvas import Canvas
from sextile.viewdata.composition import Composition
from sextile.viewdata.controls import Colour
from sextile.viewdata.font import load_font

router = PageRouter()


@router.page("2", name="banner", title="Banner")
async def banner(request: PageRequest) -> Page:
    def draw(canvas: Canvas, row: int) -> None:
        layout = Composition()
        lettering.boxed(layout, row, "NEWS", load_font("boldbash"), Colour.YELLOW, Colour.BLUE)
        lettering.boxed(layout, row + 6, "NEWS", load_font("acorn"), Colour.CYAN, Colour.MAGENTA)
        layout.draw(canvas)

    return PageLayout(parts=[OnOneFrame(Custom(rows=11, draw=draw))]).build(request)


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

 BANNER                               2a
  
              🬱🬹🬏🬹🬹🬓🬹🬦🬓🬵🬹🬓              
              █▐▌█🬋 █🬻▌🬎🬩🬓              
              🬎🬉🬄🬎🬎🬄🬆🬁🬄🬎🬎🬀              
                                        
                                        
                                        
             🬹 🬹🬦🬚🬋🬃🬹 🬦🬓🬵🬋🬱             
             █🬪█▐🬛🬋 █🬷🬷▌🬊🬋🬱             
             🬎 🬎🬉🬌🬋🬃🬎🬀🬊🬄🬊🬋🬆             
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
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lettering.boxed(layout, row, word, face, text_colour, box_colour) measures the word, draws the box to fit, and sets the word inside it. The two faces above draw the same word to different widths, because a face carries its own advances; the catalogue sets a specimen of each.

Fit a banner to the row

The spacing decides whether a banner fits the forty columns at all. Measured with the shipped acorn face:

	blocks	cells, with the attribute	fits on a row?
BBC CEEFAX, fixed	80	41	no
BBC CEEFAX, proportional	66	34	yes
BBC CEEFAX, kerned	64	33	yes
STARDOT, fixed	55	29	yes
STARDOT, proportional	48	25	yes
STARDOT, kerned	45	24	yes

A fixed-width face cannot draw the Ceefax banner — it is over by a cell — where a proportional one draws it with five cells to spare. Measure a word with cells_needed(word, face, spacing=) before drawing it, and set the spacing with Spacing; Large lettering shows the three spacings side by side, and the mosaic-fonts explanation says why the advance belongs to the font.