hydra-synth/src/lib/mouse.js

base synth for hydra-editor

// based on https://github.com/mikolalysenko/mouse-change

export default mouseListen

import mouse from './mouse-event.js'

function mouseListen (element, callback) {
  if (!callback) {
    callback = element
    element = window
  }

  var buttonState = 0
  var x = 0
  var y = 0
  var mods = {
    shift: false,
    alt: false,
    control: false,
    meta: false
  }
  var attached = false

  function updateMods (ev) {
    var changed = false
    if ('altKey' in ev) {
      changed = changed || ev.altKey !== mods.alt
      mods.alt = !!ev.altKey
    }
    if ('shiftKey' in ev) {
      changed = changed || ev.shiftKey !== mods.shift
      mods.shift = !!ev.shiftKey
    }
    if ('ctrlKey' in ev) {
      changed = changed || ev.ctrlKey !== mods.control
      mods.control = !!ev.ctrlKey
    }
    if ('metaKey' in ev) {
      changed = changed || ev.metaKey !== mods.meta
      mods.meta = !!ev.metaKey
    }
    return changed
  }

  function handleEvent (nextButtons, ev) {
    var nextX = mouse.x(ev)
    var nextY = mouse.y(ev)
    if ('buttons' in ev) {
      nextButtons = ev.buttons | 0
    }
    if (nextButtons !== buttonState ||
      nextX !== x ||
      nextY !== y ||
      updateMods(ev)) {
      buttonState = nextButtons | 0
      x = nextX || 0
      y = nextY || 0
      callback && callback(buttonState, x, y, mods)
    }
  }

  function clearState (ev) {
    handleEvent(0, ev)
  }

  function handleBlur () {
    if (buttonState ||
      x ||
      y ||
      mods.shift ||
      mods.alt ||
      mods.meta ||
      mods.control) {
      x = y = 0
      buttonState = 0
      mods.shift = mods.alt = mods.control = mods.meta = false
      callback && callback(0, 0, 0, mods)
    }
  }

  function handleMods (ev) {
    if (updateMods(ev)) {
      callback && callback(buttonState, x, y, mods)
    }
  }

  function handleMouseMove (ev) {
    if (mouse.buttons(ev) === 0) {
      handleEvent(0, ev)
    } else {
      handleEvent(buttonState, ev)
    }
  }

  function handleMouseDown (ev) {
    handleEvent(buttonState | mouse.buttons(ev), ev)
  }

  function handleMouseUp (ev) {
    handleEvent(buttonState & ~mouse.buttons(ev), ev)
  }

  function attachListeners () {
    if (attached) {
      return
    }
    attached = true

    element.addEventListener('mousemove', handleMouseMove)

    element.addEventListener('mousedown', handleMouseDown)

    element.addEventListener('mouseup', handleMouseUp)

    element.addEventListener('mouseleave', clearState)
    element.addEventListener('mouseenter', clearState)
    element.addEventListener('mouseout', clearState)
    element.addEventListener('mouseover', clearState)

    element.addEventListener('blur', handleBlur)

    element.addEventListener('keyup', handleMods)
    element.addEventListener('keydown', handleMods)
    element.addEventListener('keypress', handleMods)

    if (element !== window) {
      window.addEventListener('blur', handleBlur)

      window.addEventListener('keyup', handleMods)
      window.addEventListener('keydown', handleMods)
      window.addEventListener('keypress', handleMods)
    }
  }

  function detachListeners () {
    if (!attached) {
      return
    }
    attached = false

    element.removeEventListener('mousemove', handleMouseMove)

    element.removeEventListener('mousedown', handleMouseDown)

    element.removeEventListener('mouseup', handleMouseUp)

    element.removeEventListener('mouseleave', clearState)
    element.removeEventListener('mouseenter', clearState)
    element.removeEventListener('mouseout', clearState)
    element.removeEventListener('mouseover', clearState)

    element.removeEventListener('blur', handleBlur)

    element.removeEventListener('keyup', handleMods)
    element.removeEventListener('keydown', handleMods)
    element.removeEventListener('keypress', handleMods)

    if (element !== window) {
      window.removeEventListener('blur', handleBlur)

      window.removeEventListener('keyup', handleMods)
      window.removeEventListener('keydown', handleMods)
      window.removeEventListener('keypress', handleMods)
    }
  }

  // Attach listeners
  attachListeners()

  var result = {
    element: element
  }

  Object.defineProperties(result, {
    enabled: {
      get: function () { return attached },
      set: function (f) {
        if (f) {
          attachListeners()
        } else {
          detachListeners()
        }
      },
      enumerable: true
    },
    buttons: {
      get: function () { return buttonState },
      enumerable: true
    },
    x: {
      get: function () { return x },
      enumerable: true
    },
    y: {
      get: function () { return y },
      enumerable: true
    },
    mods: {
      get: function () { return mods },
      enumerable: true
    }
  })

  return result
}