Using keys to move stimulus: quick and slow movement while keeping record of the pressed keys

[jonathan.kominsky]

@ktddzkwsk

Unfortunately, when I add another getKeys() ‘s’ and ‘d’ are not being recorded, I assume because they are assigned in keysB and getting cleared from the buffer?

Yep, but just set clear=False for keysB as well and only set it to true for the final getKeys that catches all of the key-presses.

@ktddzkwsk

Ideally, I would like to achieve different movement speeds with the same keys, so one press of ‘s’ would move the marker by one increment, but if it’s pressed down it would move the marker quickly. Like if you press left and right arrows in a word document. Can anyone think of a way to code this?

Basically what you’re looking for is adding a counter for consecutive frames on which ‘s’ or ‘d’ has been detected as pressed, and then modifying the speed of the position marker accordingly. Something like this might work:

    if keysB:
        for k in keysB:
            keyB = keysB[-1].name
            if keyB == 's':
                dcounter = 0 # Resetting the counter for D if it is not pressed
                speed = .01
                scounter += 1
                if scounter >= 40:
                    speed = .2
                elif scounter >= 20:
                    speed = .1
                elif scounter >= 10:
                    speed = .05
                markerStim.pos -= [speed, 0]

And the same for D, and just have it that if keysB is false or is not S, the counter resets to 0.

It might be tricky to do with getKeys because of the buffer-clear issue. The solution offered here might be a reasonable alternative if you have trouble getting it to work with getKeys:

Tracking Key release

I’ve found a way to do this without iohub (which I still have trouble with on my mac, the permissions thing has nearly bricked my laptop twice now). I sadly don’t have the original reference but I picked this up from a thread in the old google group and digging through some of the pyglet documentation. Basically when you create your stimulus window, which by default is a pyglet window, you can bypass PsychoPy’s event system and get pyglet to pass keypress events directly to you. Declare your wi…