Yes, that's what I tried - but there was a case when next press or release happens while signal is already off-scale from previous event, and I failed to find a

Yes, that's what I tried - but there was a case when next press or release happens while signal is already off-scale from previous event, and I failed to find any sane way to solve that case. Also, the scale on the images is 500ms per one red square, so you can see that waveforms extend over hundreds of milliseconds - thus there will be unbearable latency with that approach.