I made this app to save cam snapshots whenever the snap shot button is pressed however when i circle back to the welcome page and then to the cam page , i get this error:
cv2image = cv2.cvtColor(self.frame, cv2.COLOR_BGR2RGBA) cv2.error: OpenCV(4.2.0) /io/opencv/modules/imgproc/src/color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'
i researched everywhere but couldnt find a way todo this. is it a limitation in opencv or tkinter?
i suspect the error could be because the previous snapshot is not cleared from cv2image but i dont know. what is the best way to make the app reset when welcome screen is called?
Attached is a working demonstration of the code the issue appears when the frontpage is recalled i get an error or sometimes just with the previous snapshot stuck on the frame screen.
how to make the app continue to work without exiting and reentering the app?
import PIL
import tkinter as tk from PIL import Image, ImageTk import cv2 import time
class FR_GUI(tk.Tk): """this is the app it inherits from tk.Tk """
def __init__(self):
super().__init__()
#self.title = "Self Registration Kiosk"
self.geometry("700x1050")
# self.attributes("-fullscreen", True)
# self.wm_attributes("-topmost", 1)
self.home = WelcomeScreen(self)
self.home.pack(expand=True,fill=tk.BOTH)
self.front = FrontPage(self)
self.second = SecondPage(self)
def welcome_screen(self):
self.front.pack_forget()
self.second.pack_forget()
self.home.pack(expand=True,fill=tk.BOTH)
def show_first(self):
self.home.pack_forget()
self.second.pack_forget()
self.front.pack(expand=True, fill=tk.BOTH)
self.front.show_frame()
def show_second(self):
self.front.cap.release()
self.front.pack_forget()
self.home.pack_forget()
self.second.pack(expand=True, fill=tk.BOTH)
class WelcomeScreen (tk.Frame): def __init__(self, master): self.master = master super().__init__(self.master) #self.input = tk.StringVar()
self.mainframe = tk.Frame(self)
self.mainframe.pack(side=tk.TOP,padx=5,pady=80)#expand=True, fill=tk.BOTH)
self.name_label = tk.Label(
self.mainframe,
text="Welcome to the self-registration portal ",
font=("Courier", 18),
)
self.name_label.pack()
self.ent_btn = tk.Button(
self.mainframe,
text="Enter",
font=("Courier", 15),
command=self.close_welcome)
self.ent_btn.pack()
def close_welcome(self):
self.master.show_first()
class FrontPage(tk.Frame): """This is a class to make the front page it inherits from tk.Frame """
def __init__(self, master):
self.master = master
super().__init__(self.master)
self.mainframe = tk.Frame(self)
self.mainframe.pack(side=tk.TOP,padx=5,pady=20,expand=True, fill=tk.BOTH)
self.name_label = tk.Label(
self.mainframe,
text="Press Snapshot, picture will be taken in: ",
font=("Courier", 13),
)
self.name_label.pack()
self.label_count = tk.Label(
self.mainframe,
)
self.label_count.pack()
self.lmain = tk.Label(
self.mainframe,
anchor=tk.CENTER
#text='cam frame'
)
self.lmain.pack()
self.ent_btn = tk.Button(
self.mainframe,
text="Take Snapshot",
font=("Courier", 15),
command=self.onClick)#self.start_cam)
self.ent_btn.pack(side = 'bottom')
self.video_source = 0
self.cap = cv2.VideoCapture(self.video_source)
#get cam width & height
self.width = self.cap.get(cv2.CAP_PROP_FRAME_WIDTH) # float
self.height = self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
def cam_release(self):
self.cap.release()
def show_frame(self):
ret, frame = self.cap.read()
frame = cv2.flip(frame, 1)
cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
img = PIL.Image.fromarray(cv2image)
imgtk = ImageTk.PhotoImage(image=img)
self.lmain.imgtk = imgtk
self.lmain.configure(image=imgtk)
self.lmain.after(10, self.show_frame)
after_id = None
def countdown(self,count):
# change text in label
self.label_count['text'] = count
if count > 0:
# call countdown again after 1000ms (1s)
self.after(1000, self.countdown, count-1)
else:
self.snapshot()
'''Start counting down.'''
def onClick(self):
self.countdown(2)
def snapshot(self):
# Get a frame from the video source
ret, frame = self.cap.read()
out_name = ("frame-" + time.strftime("%d-%m-%Y-%H-%M-%S") + ".jpg")
cv2.imwrite(out_name, frame)
self.cam_release()
print(out_name)
self.master.show_second()
class SecondPage(tk.Frame): """This is a class to make the second page it inherits from tk.Frame """
def __init__(self, master):
self.master = master
super().__init__(self.master)
self.firstName = tk.StringVar()
self.lastName = tk.StringVar()
#self.email = tk.StringVar()
self.ph_one = tk.IntVar()
self.mainframe = tk.Frame(self)
self.mainframe.pack(fill=tk.BOTH, pady=80)
self.label = tk.Label(
self.mainframe, text="person not registered. \n please register: "
)
self.label.pack()
self.top_frame = tk.Frame(self)
self.top_frame.pack(side=tk.TOP,padx=5,pady=10)#expand=True, fill=tk.BOTH)
self.center_frame = tk.Frame(self)
self.center_frame.pack(side=tk.TOP,padx=5,pady=10)
self.low_frame = tk.Frame(self)
self.low_frame.pack(side=tk.TOP, padx=5,pady=10)#,expand = True)
fname_label = tk.Label(self.top_frame,text="First Name",font=("Courier", 13))
self.fname_entry = tk.Entry(self.top_frame, textvariable = self.firstName)
lname_label = tk.Label(self.top_frame,text="Last Name ",font=("Courier", 13))
self.lname_entry = tk.Entry(self.top_frame, textvariable = self.lastName)
fname_label.grid(row=0, column=0)
self.fname_entry.grid(row=0, column=1)
lname_label.grid(row=1, column=0)
self.lname_entry.grid(row=1, column=1)
self.home_button = tk.Button(self.low_frame,text='Home',command=self.clear_widgets).grid(row=0,column=0,pady=4)
self.submit_button = tk.Button(self.low_frame,text='Submit',command=self.form_submit).grid(row=0,column=1,pady=10)
def form_submit(self):
self.f_name = self.firstName.get()
self.l_name = self.lastName.get()
self.submit_label = tk.Label(self.center_frame,text="Thank you "+self.f_name+" "+self.l_name+" for your registeration",font=("Courier", 13))
self.submit_label.grid(row=2,column=0)
self.submit_label['text'] = ""
def clear_widgets(self):
self.refresh()
self.master.welcome_screen()
def refresh(self):
self.fname_entry.delete(0,"end")
self.lname_entry.delete(0,"end")
self.fname_entry.focus_set()
app = FR_GUI() app.bind("<escape>", exit) app.mainloop()
