How to press and hold one key to move the stimulus?

Builder
1

Hi there,

In my current Pavlovia experiment, I can press the arrow keys to adjust the location of an image. But each key press only increases or decreases the position of the image by 4 pix. How can I make it so that when I press down the right key, the image would keep moving right until I release the right key?

I’ve tried using this solution, but it didn’t work.

https://discourse.psychopy.org/t/how-to-detect-whether-if-a-key-is-being-pressed-down/15830/15

I’ve also tried storing the keypress duration, then set the duration to null, as following, but it’s not working as the image doesn’t move when I press the arrow keys.

begin experiment (these code is for restricting the range of all the possible locations for the image)

x_basic = ((is_right)? 115: -115);
do{
    bx = (Math.random() * 160) - 80;
    by = (Math.random() * 160) - 80;
}while ((bx*bx) + (by*by) > 80*80);
startx = bx;
starty = by;
img_x = x_basic + bx;
img_y = y_basic + by;
old_key_length = 0;

begin routine

trial_resp.getKeys({"clear": true});
document.body.style.cursor='auto';

each frame

kp = trial_resp.getKeys({"waitRelease": false, "clear": false});
if ((kp.length > 0)) {
    pressed = kp[kp.length-1].name;
    duration = kp[kp.length-1].duration;
    if ((pressed === "up"&& duration == null)) {
        if ((bx*bx) + ((by+4)*(by+4)) <= 80*80){
            by += 4;
           img_y = y_basic + by;
        }
    } else if ((pressed === "down"&& duration == null)) {
        if ((bx*bx) + ((by-4)*(by-4)) <= 80*80){
            by -= 4;
            img_y = y_basic + by;
        }
    } else if ((pressed === "left"&& duration == null)) {
        if (((bx-4)*(bx-4)) + (by*by) <= 80*80){
            bx -= 4;
            img_x = x_basic + bx;
        }
    } else if ((pressed === "right"&& duration == null)) {
        if (((bx+4)*(bx+4)) + (by*by) <= 80*80){
            bx += 4;
           img_x = x_basic + bx;
        }
    }

    old_key_length = kp.length;
}

Thank you so much! Deeply appreciated!

2

My method (the topic you are referring to) works fine. Which PsychoJS version are you on?

From what I see you haven’t initialized the keyboard object. That maybe why it2s not working.