create-bitmap-font

Create a bitmap sprite font in node

npm install @nrkn/create-bitmap-font

In the example we create a bitmap font and then use it to draw some text:

``js
import { promises } from 'fs'
import { createBitmapFont, drawText } from '@nrkn/create-bitmap-font'

const { readFile, writeFile } = promises

// colors - 4 bytes in rgba order
const fill = [0xff, 0xc2, 0x0e, 0xff]
const bg = [ 0, 0, 0, 0 ]

const start = async () => {
// let's just use the printable chars from 7-bit ascii
// eg [ 33, 34, ...etc ]
const codes = createSeq(95, i => i + 33)

// otf or ttf buffer
const font = await readFile('some-font.otf')

const bitmapFont = createBitmapFont(font, 32, { fill, bg, codes })

const { offsets, pngBuffer } = bitmapFont

// save the bitmap font and the text metrics
await writeFile( 'some-font.png', pngBuffer )
await writeFile( 'some-font.json', JSON.stringify( offsets, null, 2 ), 'utf8' )

// create text drawing function
const draw = drawText( bitmapFont.canvas, bitmapFont.offsets )

// first we will create a round trip and see if it matches the font bitmap

const text = codes.map( c => String.fromCharCode( c ) ).join( '' )

// returns a canvas
const roundTrip = draw( text )

// turn it into a PNG
const roundPng = roundTrip.toBuffer('image/png')

// should be the same as the pngBuffer created by createBitmapFont
await writeFile( 'test-round.png', roundPng )

// now write some arbitrary text

const testText = 'Hello, world'

const testDraw = draw( testText )

const testPng = testDraw.toBuffer( 'image/png' )

await writeFile( 'test-out.png', testPng )
}

const createSeq = (length, cb) =>
Array.from({ length }, (_v, k) => cb(k))

start().catch(console.error)
``

todo

Should be able to use in browser too, especially as we are using a canvas
compatible module in node - add a factory function that takes deps like canvas
etc and returns a create bitmap font function

license

MIT License

Copyright (c) 2022 Nik Coughlin

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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SOFTWARE.