Button Debounce doesn't work correctly

https://github.com/dotnet/iot/pull/1720

@pgrawehr

There’s an issue with this implementation, when the button is held down for longer then the debounce timeout. When it is released now, there will be a “pressed” event due to the bounces happening during release, and the desired “released” event is fired, due to the debouncing getting started by “pressed”.

I solved this by using a timer for debounce that checks the current button state when finished. Something like below, same for HandleButtonReleased()

protected void HandleButtonPressed()
{
    _stateForAfterDebounce = true;  // keep track of the button state, even with bounces, so we can get the current state at the end of the debounce timeout

    if (IsPressed)  // already pressed
        return;
    if (_debounceTimer!=null)   // currently debouncing
        return;

    IsPressed = true;

    if (_debounceTime.TotalMilliseconds > 0)
    {
        _debounceTimer = new Timer((o) =>
        {
            _debounceTimer?.Dispose();
            _debounceTimer = null;

            if (_stateForAfterDebounce == false)  // Button might have been been released while we were in the debounce. Check current state and handle
                HandleButtonReleased();
        }, null, _debounceTime, Timeout.InfiniteTimeSpan);
    }

    ButtonDown?.Invoke(this, new EventArgs());

    if (IsHoldingEnabled)
    {
        _holdingTimer = new Timer(StartHoldingHandler, null, (int)_holdingMs, Timeout.Infinite);
    }
}

[krwq]

@W1zzardTPU do you feel like sending a PR with a fix? I’m sure there will be more people hitting this. Perhaps we should be doing debounce on both pressing and releasing button (I didn’t look at the implementation so take what I’m saying with grain of salt)

[W1zzardTPU]

Still no time, for a quick test, try running a loop of random presses/releases to simulate bounce.

both before and after the sleep