add launch control xl support, and chunk mixer

lib/midi-port.js

@@ -11,6 +11,7 @@ function MidiPort (context, onSwitch) {
   var obs = Prop()
   var nextValue = null
   var settingNext = false
+  obs.override = Prop(false)
 
   obs.stream = Prop()
 
@@ -29,13 +30,15 @@ function MidiPort (context, onSwitch) {
     var stack = stacks.get(obs())
     if (stack && last(stack) !== obs) {
       var lastTop = last(stack)
-      var index = stack.indexOf(obs)
-      if (~index) {
-        stack.splice(index, 1)
+      if (!lastTop.override()) {
+        var index = stack.indexOf(obs)
+        if (~index) {
+          stack.splice(index, 1)
+        }
+        stack.push(obs)
+        lastTop && lastTop.refresh()
+        refresh()
       }
-      stack.push(obs)
-      lastTop && lastTop.refresh()
-      refresh()
     }
   }
 
@@ -48,6 +51,16 @@ function MidiPort (context, onSwitch) {
     }
   }
 
+  obs.previous = function () {
+    var stack = stacks.get(obs())
+    if (stack && last(stack) === obs) {
+      var previous = stack[stack.length - 2]
+      if (previous) {
+        previous.grab()
+      }
+    }
+  }
+
   obs.destroy = function () {
     while (listeners.length) {
       listeners.pop()()

lib/scale-interpolate.js

@@ -0,0 +1,32 @@
+module.exports = scaleInterpolate
+
+function scaleInterpolate (currentValue, toValue, state) {
+  var difference = absDifference(currentValue, toValue)
+  if (difference != null && difference > 3 && (!state.lastSync || Date.now() - state.lastSync > 50)) {
+    if (state.interpolatingFrom == null) {
+      state.interpolatingFrom = toValue
+    }
+    if (absDifference(state.interpolatingFrom, currentValue) < difference) {
+      if (currentValue <= 0) {
+        toValue = 1
+      } else {
+        toValue = toValue / state.interpolatingFrom * currentValue
+      }
+    } else {
+      state.interpolatingFrom = toValue
+      toValue = currentValue
+    }
+    state.lastSync = null
+  } else {
+    state.interpolatingFrom = null
+    state.lastSync = Date.now()
+  }
+
+  return toValue
+}
+
+function absDifference (a, b) {
+  if (a != null && b != null) {
+    return Math.abs(a - b)
+  }
+}

lib/watch-knobs.js

@@ -0,0 +1,64 @@
+var watch = require('observ/watch')
+
+module.exports = watchKnobs
+
+function watchKnobs (stream, keys, listener, defaultValue) {
+  var currentStream = null
+  var release = watch(stream, set)
+  var currentValues = []
+  var broadcastedValues = []
+  var broadcastedAt = []
+  var lastChangeAt = []
+  var throttling = []
+  var timers = []
+  var minDelay = 10
+
+  return function () {
+    release && release()
+    currentStream && currentStream.removeListener('data', handler)
+  }
+  // scoped
+
+  function handler (message) {
+    var key = message[0] + '/' + message[1]
+    var index = keys.indexOf(key)
+    if (~index) {
+      broadcast(index, message[2])
+    }
+  }
+
+  function broadcast (index, value) {
+    currentValues[index] = value
+    if (!throttling[index]) {
+      if (Date.now() - lastChangeAt[index] > minDelay) {
+        broadcastNow(index, value)
+      } else {
+        throttling[index] = true
+        timers[index] = setInterval(function () {
+          broadcastNow(index, currentValues[index])
+        }, minDelay)
+      }
+    }
+    lastChangeAt[index] = Date.now()
+  }
+
+  function broadcastNow (index, value) {
+    broadcastedAt[index] = Date.now()
+
+    if (broadcastedValues[index] !== value) {
+      broadcastedValues[index] = value
+      listener(index, value)
+    }
+
+    if (throttling[index] && broadcastedAt[index] - lastChangeAt[index] > minDelay) {
+      throttling[index] = false
+      clearInterval(timers[index])
+    }
+  }
+
+  function set (newStream) {
+    currentStream && currentStream.removeListener('data', handler)
+    newStream && newStream.on('data', handler)
+    currentStream = newStream
+  }
+}

nodes/global-launch-control-xl/index.js

@@ -0,0 +1,7 @@
+module.exports = {
+  name: 'Launch Control XL',
+  portMatch: /^Launch Control XL/,
+  node: 'global/launch-control-xl',
+  group: 'global-controllers',
+  object: require('./object')
+}