现在无法使用python和opencv获取密钥代码

Question

okay, i've been using this basic thing for last few months to get key events such as ESC key, or E key etc, to do things when they are pressed in my opencv program.

Now earlier, for detecting ESC key, the code was there already in all the examples in the samples folder and on the web. I understood that. From that i hacked up a way to get the keycodes for other keys, such as E and S etc. Because i wanted to use them to take snapshots of the current frames under processing in my program. And it worked, i found out for E its 101, like for ESC its 27 But that's the ASCII value or something? I'm not sure.

This is what i'm doing now also, but its just not printing the keycode:

import cv

while True:

   k = cv.WaitKey(100) % 0x100

   if k != 255:
        print k

So that when i press some key which doesn't have a value of 255, i should be notified that the that key was pressed. It works in my opencv programs:

while True:



  k = cv.WaitKey(10)

  if k % 0x100 == 27: # if ESC key is pressed....

    #cv.SaveImage(filename,threshed2)
    cv.DestroyWindow("threshed") #Destroy the window of detection results
    cv.DestroyWindow("gray")
    cv.DestroyWindow("edge")
    cv.DestroyWindow("pupil")
    #cv.DestroyWindow('smooth')
    break

  elif k == 101: #if E is pressed
        eyeSnap = "C:\\Users\\ronnieaka\\Desktop\\PROJ\\openCV\\eyeSnaps\\det_pupil.jpg"
        cv.SaveImage(eyeSnap,image)

I know its a basic thing and i just was playing around to get the keys pressed and do something else not related to OpenCV Why i'm i not getting 101 from the previous code when i press E or the code for other keys when i press them?

Answer 1

This used to be super simple:

k = cv.WaitKey(10)
if k == 27:         
    # ESC key was pressed

The code above don't work on your system?

Answer 2

I have the same problem as you, but I always could not get keycode (only get 255)
I find it because the cv.WaitKey only receive key from the windows you create not python command line :)