Define Tuple with PuthonObject

Trying to convert the below opencv python code to mojolang:

import cv2 as cv
 
cap = cv.VideoCapture(0)
if not cap.isOpened():
    print("Cannot open camera")
    exit()
while True:
    # Capture frame-by-frame
    ret, frame = cap.read()
 
    # if frame is read correctly ret is True
    if not ret:
        print("Can't receive frame (stream end?). Exiting ...")
        break
    # Our operations on the frame come here
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    # Display the resulting frame
    cv.imshow('frame', gray)
    if cv.waitKey(1) == ord('q'):
        break
 
# When everything done, release the capture
cap.release()
cv.destroyAllWindows()

import cv2 as cv
 
cap = cv.VideoCapture(0)
if not cap.isOpened():
    print("Cannot open camera")
    exit()
while True:
    # Capture frame-by-frame
    ret, frame = cap.read()
 
    # if frame is read correctly ret is True
    if not ret:
        print("Can't receive frame (stream end?). Exiting ...")
        break
    # Our operations on the frame come here
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    # Display the resulting frame
    cv.imshow('frame', gray)
    if cv.waitKey(1) == ord('q'):
        break
 
# When everything done, release the capture
cap.release()
cv.destroyAllWindows()

So, I wrote the below:

from python import Python

def main():
    # This is equivalent to Python's `import numpy as np`
    cv = Python.import_module("cv2")

    cap = cv.VideoCapture(0)
    if not cap.isOpened():
        print("Cannot open camera")
        # exit()
    while True:
        # Capture frame-by-frame
        var ret, frame = cap.read() # I get the error here
    
        # if frame is read correctly ret is True
        if not ret:
            print("Can't receive frame (stream end?). Exiting ...")
            break
        # Our operations on the frame come here
        gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
        # Display the resulting frame
        cv.imshow('frame', gray)
        if cv.waitKey(1) == ord('q'):
            break
    
    # When everything done, release the capture
    cap.release()
    cv.destroyAllWindows()

from python import Python

def main():
    # This is equivalent to Python's `import numpy as np`
    cv = Python.import_module("cv2")

    cap = cv.VideoCapture(0)
    if not cap.isOpened():
        print("Cannot open camera")
        # exit()
    while True:
        # Capture frame-by-frame
        var ret, frame = cap.read() # I get the error here
    
        # if frame is read correctly ret is True
        if not ret:
            print("Can't receive frame (stream end?). Exiting ...")
            break
        # Our operations on the frame come here
        gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
        # Display the resulting frame
        cv.imshow('frame', gray)
        if cv.waitKey(1) == ord('q'):
            break
    
    # When everything done, release the capture
    cap.release()
    cv.destroyAllWindows()

I got the error: declaration must have either a type or an initializer at the line var ret, frame = cap.read()

4 Replies

DobyDabaDu•2mo ago

Dont use var in def function (to solve the issue)

cr = cap.read()
ret = cr[0]
frame = cr[1]

cr = cap.read()
ret = cr[0]
frame = cr[1]

Hasan YousefOP•2mo ago

I got use of unknown declaration 'ret'

DobyDabaDu•2mo ago

This is a working approach

Hasan YousefOP•2mo ago

Thanks a lot, it worked well.

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Define Tuple with PuthonObject