[Airtest]6.[win]Record screen wh

Airtest provides recording screen API only for Android, that's why we need to write recording tool ourselves.

1.Basic recording function

I find a recording screen tool with python. In this way, I can get a record.avi file with the whole screen activities.

import numpy as np
import cv2
from PIL import ImageGrab
import pyautogui as pyag

fourcc = cv2.VideoWriter_fourcc("X", "V", "I", "D")
out = cv2.VideoWriter('record.avi', fourcc, 50, pyag.size())
while True:
    img = ImageGrab.grab()
    img_np = np.array(img)
    frame = cv2.cvtColor(img_np, cv2.COLOR_BGR2RGB)
    out.write(frame)
    cv2.imshow('screen', frame)
    if cv2.waitKey(1) == 27:   # press Esc to end recording
         break
out.release()
cv2.destroyAllWindows()

Hint:
pip install opencv-python for cv2
pip install Pillow for PIL, which is built-in in Python3

2.Multi threading

We can use a dedicated threading for recording when testing proceeds.

import threading

class RecordingTool:
    @staticmethod
    def start_recording():
        # above recording codes...

threading.Thread(target=RecordingTool.start_recording).start()
# call testing...

3.How to end recording

Recording can be ended by pressing Esc key, which means we can't feel free to press Esc key during testing. We need to find another way——thread event.
threading.Event() will create a event flag, which is False in default.
event.set() will set the flag to True
event.clear() will set the flag to False
event.isSet() will tell you if the flag is True
OK, the code can be changed to:

class RecordingTool:
    @staticmethod
    def start_recording():
        # recording codes...

event = threading.Event()
threading.Thread(target=RecordingTool.start_recording).start()
# call testing...
event.set()

4.Avoid Exception effect

The ending recording code couldn't be executed when testing code throw an exception. We can use try...except...finally... module to avoid the effect.
And in order to make the code more readable, we add a end_recording method. The code will finally look like:

event = threading.Event()

class RecordingTool:
    @staticmethod
    def start_recording():
        # recording codes...
    
    @staticmethod
    def end_recording():
        event.set()

try:
    threading.Thread(target=RecordingTool.start_recording).start()
    # call testing...
except Exception as e:
    raise Exception(str(e))
finally:
    threading.Thread(target=RecordingTool.stop_recording).start()