/// <summary>
/// Constructor
/// </summary>
/// <param name="stateMachineInputCallback">delegate to call when there's an event to report</param>
public DelcomLight(MainAppLogic.EnqueueStateMachineInput stateMachineInputCallback, TimeSpan holdTime)
{
hUSB = DelcomLightWrapper.TryOpeningDelcomDevice();
Delcom.DelcomEnableAutoConfirm(hUSB, 0);
// Make sure we always start turned off
DelcomLightWrapper.DelcomLEDAllAction(hUSB, DelcomLightWrapper.LightStates.Off);
// remember the delegate so we can invoke when we get input
this.stateMachineInputCallback = stateMachineInputCallback;
//Initialize hold threshold from argument passed from Main
this.holdThreshold = holdTime;
// start a background thread to poll the device for input
BackgroundWorker bgw1 = new BackgroundWorker();
bgw1.DoWork += delegate { this.BackgroundPollingWorker(); };
bgw1.RunWorkerAsync();
}
/// <summary>
/// Runs on a background thread to monitor the button state and will dispatch events back to the main thread
/// </summary>
private void BackgroundPollingWorker()
{
ButtonState currentState = ButtonState.NotPressed;
int iterationsSinceLastButtonRelease = 0;
int iterationsSinceLastButtonDown = 0;
const int buttonReleaseTolerance = 2; // magic number that works well in practice
//Timer to determine how long the button has been held down for
TimeSpan holdDuration = TimeSpan.Zero;
//The time when the button was last in a down state. Used for hardware error correction.
DateTime lastButtonDownTime = DateTime.MinValue;
//The time when the button was last in an up state. Used for hardware error correction.
DateTime lastButtonUpTime = DateTime.MinValue;
//Boolean switch for determining if a button was held for longer than the hold threshold while it is still being held down.
Boolean buttonHeld = false;
// Loop endlessly until we're asked to stop
while (!this.shouldStop)
{
//Check if light is still connected
bool isStillConnected = DelcomLightWrapper.isButtonConnected(hUSB);
//If not still connected, start loop to poll for connection until it is connected.
if (!isStillConnected)
{
DelcomLightWrapper.CloseDelcomDevice(hUSB);
hUSB = DelcomLightWrapper.TryOpeningDelcomDevice();
}
if ((DateTime.UtcNow - lastButtonUpTime) > minTimeBetweenClicks)
{
// Get the current state of the button
ButtonState newState = DelcomLightWrapper.DelcomGetButtonStatus(hUSB);
if (newState == ButtonState.Unknown)
{
throw new NotImplementedException();
}
else if (newState != currentState)
{
// The state has changed, so we need to handle it
if (newState == ButtonState.NotPressed)
{
// We were previously in a pressed state, but the button on the light is flaky, so we need
// to make sure the button has really been released, so we'll wait a few iterations.
iterationsSinceLastButtonRelease++;
if (iterationsSinceLastButtonRelease > buttonReleaseTolerance)
{
// Only remember the currentstate as changed if we're outside of our tolerance
currentState = newState;
//Button just released so reset timer
iterationsSinceLastButtonRelease = 0;
//Fire a button up event. This will only cause the state machine to act if in a previewing state with nothing queued.
//It will turn off the red light that is on when the button is being held down in that case
if (stateMachineInputCallback != null)
{
StateMachine.StateMachineInputArgs buttonUpArgs = new StateMachine.StateMachineInputArgs(StateMachine.StateMachineInput.ButtonUp);
stateMachineInputCallback(buttonUpArgs);
}
//If a button held event was already fired, we don't want to fire a button pressed event in this case
if (!buttonHeld)
{
// Notify that we've had a button press
if (stateMachineInputCallback != null)
{
StateMachine.StateMachineInputArgs buttonArgs = new StateMachine.StateMachineInputArgs(StateMachine.StateMachineInput.ButtonPressed);
stateMachineInputCallback(buttonArgs);
}
}
lastButtonUpTime = DateTime.UtcNow;
//reset button held, as it is no longer being held if it was before
buttonHeld = false;
}
}
else if (newState == ButtonState.Pressed)
{
// We were previously in a pressed state, but the button on the light is flaky, so we need
// to make sure the button has really been released, so we'll wait a few iterations.
iterationsSinceLastButtonDown++;
if (iterationsSinceLastButtonDown > buttonReleaseTolerance)
{
// The button has just been pressed
// Only remember the current state as changed if we're outside of our tolerance
currentState = newState;
//Button just pressed so reset timer
iterationsSinceLastButtonRelease = 0;
//Fire a button down event. This will only cause the state machine to act if in a previewing state with nothing queued.
//It will turn on the red light that is on when the button is being held down in that case
if (stateMachineInputCallback != null)
{
StateMachine.StateMachineInputArgs buttonArgs = new StateMachine.StateMachineInputArgs(StateMachine.StateMachineInput.ButtonDown);
stateMachineInputCallback(buttonArgs);
}
//Set last button down time to current time, as button was just pressed down
lastButtonDownTime = DateTime.UtcNow;
}
}
}
else if (newState == ButtonState.Pressed)
{
//Button has been held, check if hold is greater than threshold
holdDuration = DateTime.UtcNow - lastButtonDownTime;
//Reset iterations since last release
iterationsSinceLastButtonRelease = 0;
//If button held event has already been fired, we don't want to fire again until the button has been released
if (!buttonHeld)
{
//If hold duration is greater than threshold we should fire a button held event
if (holdDuration > holdThreshold)
{
// Notify that we've had a button held
if (stateMachineInputCallback != null)
{
StateMachine.StateMachineInputArgs buttonArgs = new StateMachine.StateMachineInputArgs(StateMachine.StateMachineInput.ButtonHeld, holdDuration);
stateMachineInputCallback(buttonArgs);
}
//We fired a button held event, so set this to true to prevent the event from being fired again while the button is still being held down.
buttonHeld = true;
}
}
}
else if (newState == ButtonState.NotPressed)
{
//Reset iterations since last press
iterationsSinceLastButtonDown = 0;
}
}
System.Threading.Thread.Sleep(RRLightProgram.Properties.Settings.Default.LightPollingIntervalMS);
}
}
