string2png/src/channels.js

Convert strings in various formats to tiny images

'use strict'

var fill = require('./fill')
  , Colour = require('deepcolour')

module.exports = function channels( data, options ) {
  if ( !Array.isArray( data ) )
    data = require('./bytes')( data, options )
  else if ( isAllColours( data ) )
    return data

  options = options || {}

  var channels = options.channels || 'rgb'

  if ( 'number' == typeof channels ) {
    channels = parseInt( channels ) || 0
    channels = 'rgba'.substr( 0, channels ) + '0'.repeat( Math.max( 0, channels - 4 ) )
  }

  if ( 'string' == typeof channels ) {
    channels = channels.split('')
  }

  if ( !Array.isArray( channels ) )
    throw new Error('options.channels must be number, string or array')

  if ( !channels.length )
    return []

  var stride = options.stride = parseInt( options.stride ) || channels.length
  var length = Math.ceil( data.length / stride )
  var result = fill( [], length, options )

  for ( var index = 0; index < length; index ++ ) {
    for ( var j = 0; j < stride; j ++ ) {
      var value = data[index*stride+j]
      let channelIndex = result[index].channelIndex( channels[j] )

      if ( channelIndex != -1 )
        result[index].setChannel( channelIndex, value )
    }
  }

  return result
}


function isAllColours( data ) {
  for ( let i = 0; i < data.length; i ++ )
    if ( !data[i].length )
      return false
 
  return true
}