loop-grid/transforms/suppressor.js

An observable collection of looped event sequences shaped to a grid.

var Observ = require('observ')
var ArrayGrid = require('array-grid')

module.exports = function (transform, shape, stride) {
  var self = Observ(ArrayGrid([], resolve(shape), resolve(stride)))

  var release = null
  var doneCallback = null

  var set = self.set
  self.set = null

  self.start = function (suppressIndexes, done) {
    self.stop()

    suppressIndexes = suppressIndexes || []

    // transform
    release = transform(suppress, suppressIndexes)

    // update observable grid
    var data = suppressIndexes.reduce(function (result, index) {
      result[index] = true
      return result
    }, [])

    set(ArrayGrid(data, resolve(shape), resolve(stride)))

    doneCallback = done
  }

  self.stop = function () {
    if (release) {
      set(ArrayGrid([], resolve(shape), resolve(stride)))
      release()
      release = null
      if (typeof doneCallback === 'function') {
        doneCallback()
        doneCallback = null
      }
    }
  }

  return self
}

function suppress (input, indexes) {
  input.data.forEach(function (loop, i) {
    if (loop && (!indexes || !indexes.length || ~indexes.indexOf(i))) {
      loop.events = []
    }
  })
  return input
}

function resolve (obs) {
  return typeof obs === 'function' ? obs() : obs
}