MediaKeys.myo

scriptId = 'com.jakechapeskie.media'

minMyoConnectVersion ='0.8.1'
scriptDetailsUrl = 'https://market.myo.com/app/54eb721ee4b07a1270f42ca2'
scriptTitle = 'Global Media Keys'

ROLL_MOTION_THRESHOLD = 7 -- degrees
SLOW_MOVE_PERIOD = 20
ROLL_INTERVAL = 5
rollReference=0
rolls = 0
enabled=false
myo.setLockingPolicy("standard")

function onForegroundWindowChange(app, title)
    return true
end

function activeAppName()
    return scriptTitle
end

function getMyoRollDegrees()
    local RollValue = math.deg(myo.getRoll())
    return RollValue
end
function onUnlock()
    enabled=false
end
function degreeDiff(value, base)
    local diff = value - base

    if diff > 180 then
        diff = diff - 360
    elseif diff < -180 then
        diff = diff + 360
    end

    return diff
end
function conditionallySwapWave(pose)
    if myo.getArm() == "left" then
        if pose == "waveIn" then
            pose = "waveOut"
        elseif pose == "waveOut" then
            pose = "waveIn"
        end
    end
    return pose
end
function onPoseEdge(pose, edge)
    pose=conditionallySwapWave(pose)
    local now = myo.getTimeMilliseconds()
  
    if (pose ~= "rest" and pose ~= "unknown") then
        -- hold if edge is on, timed if edge is off
        myo.unlock(edge == "off" and "timed" or "hold")
    end
    --Hold to activate
    if edge == "on" then
        if pose == "fist" then
            moveActive = edge == "on"
            rollReference = getMyoRollDegrees()
            rolls = 0
            enabled=true
        elseif pose =="waveIn" then
            myo.mediaKey("previous")
        elseif pose =="waveOut" then
            myo.mediaKey("next")
        elseif pose =="fingersSpread" then
            myo.mediaKey("play_pause")
        else
            enabled=false
        end
    end
end

function onPeriodic()
    if (enabled) then
        local relativeRoll = degreeDiff(getMyoRollDegrees(), rollReference)
        local newRolls = math.floor(relativeRoll / ROLL_INTERVAL)
        local volumeKey = newRolls < rolls and "volume_down" or "volume_up"
        local deltaRolls = math.abs(newRolls - rolls)

        if (deltaRolls > 0) then
            for i=1,deltaRolls do
                myo.mediaKey(volumeKey);
            end
        end
        rolls = newRolls
    end
end