Handle the keyboard Task

Handle the keyboard Task

1. Waiting fuction of keyboard input

cv2.waitKey(delay=None) -> retval

• delay : Waiting time ex) delay <= 0 is infinite delay. defautl value is 0.

• retval : Putted key (ASCII code). ex) if not key is putted,it’s -1.

• Note
  • cv2.waitKey() function opearates when OpenCV window is opened.
  • If you want to check the specific key press, you use the ord() function.

       while True:
      if cv2.waitKey() == ord('q'):
      break
    

    *** Main special Key code : 27 (ESC), 13 (ENTER), 9 (TAB)

2. Handle the mouse event

• the function that calls back the mouse event.

cv2.setMouseCallback(windowName, onMouse, param=None) -> None

• windowName : Window name that mouse event handle.
• onMouse : The callback function for handle mouse event.
  • It should follow like that frame

      onMouse(event,x,y,flags,param) -> None
    

• param : data that pass to callback funtion

3. THe frame that handle mouse event function(callback function)

onMouse(event,x,y,flags,param) -> None

• event : The sort of mouse event. ex) constant starting with cv.EVENT_FLAG

• x : x coordination
• y : y coordination
• flags : The situation when break mouse event ex) constant starting with cv.EVENT_FLAG
• param : The data that is setted from cv2.setMouseCallback() function.

4. The method How to check the operation time

• Computer Vision generally handles high capacity data. So We should manage the final result through series of processes checking the operation time.

• TickMeter class could check the operation time in OpenCV

cv2.TickMeter() -> tm

• tm : cv2.TickMeter object
• tm.start() : start time check
• tm.stop() : stop time check
• tm.reset() : initialize time check
• tm.getTimeSec() : return the time check per second
• tm.getTimeMilli() : return the time check per milli second
• tm.getTimeMicro() : return the time check per micro second