Develop Reference

How can I preview streaming images in tkinter with Allied Vision camera that uses Vimba SDK?

I want to display images from an Allied Vision camera inside a tkinter frame using OpenCV and the SDK for the camera, VimbaPython.
The only possible way to initialize the camera is with a Python with statement:
with Vimba.get_instance() as vimba:
cams = vimba.get_all_cameras()
with cams[0] as camera:
camera.get_frame()
# Convert frame to opencv image, then use Image.fromarray and ImageTk.PhotoImage to
# display it on the tkinter GUI
Everything works fine so far. But I don't only need a single frame. Instead, I need to continuously get frames and display them on the screen so that it is streaming.
I found that one way to do it is to call the .after(delay, function) method from a tkinter Label widget.
So, after obtaining one frame, I want to call the same function to get a new frame and display it again. The code would look like that:
with Vimba.get_instance() as vimba:
cams = vimba.get_all_cameras()
with cams[0] as camera:
def show_frame():
frame = camera.get_frame()
frame = frame.as_opencv_image()
im = Image.fromarray(frame)
img = Image.PhotoImage(im)
lblVideo.configure(image=img) # this is the Tkinter Label Widget
lblVideo.image = img
show_frame()
lblVideo.after(20, show_frame)
Then this shows the first frame and stops, throwing an error saying that Vimba needs to be initialized with a with statement. I don't know much about Python, but it looks like when I call the function with the .after() method it ends the with statement.
I would like to know if it is possible to execute this show_frame() function without ending the with. Also, I can't initialize the camera every time because the program goes really slow.
Thank you

I know this question is pretty old, but I ran into a similar problem with the Allied Vision cameras and found the solution to be relatively robust. So I hope this helps someone, even if not the OP.
An alternative to using with statements is using __enter__ and __exit__ (see sample here). With this, I created a class for the Vimba camera and during the __init__ I used these functions twice: once to initialize the Vimba instance, and once to open the camera itself. An example as follows...
vimba_handle = Vimba.get_instance().__enter__()
camera = vimba_handle.get_all_cameras()[0].__enter__()
I'll include a longer snippet as code as well, but please note my purpose was slightly different the OP's intent. Hopefully, it is still useful.
class VimbaCam:
def __init__(self, device_id=0):
# Variables
self.current_frame = np.array([])
self.device = None
self.device_id = device_id
self.vimba_handle = Vimba.get_instance().__enter__()
self.is_streaming = False
self.scale_window = 4
self.stream_thread = threading.Thread(target=self.thread_stream, daemon=True)
# Default settings
self.auto_exposure = "Off"
self.auto_gain = "Off"
self.acquisition = "Continuous"
self.exposure_us = 200000
self.fps = 6.763
self.gain = 0
self.gamma = 1
self.open()
def close(self):
if self.device is not None:
if self.is_streaming:
self.stop_stream()
time.sleep(1)
self.device.__exit__(None, None, None)
self.vimba_handle.__exit__(None, None, None)
def open(self):
cams = self.vimba_handle.get_all_cameras()
if not cams:
error_check(151, currentframe())
else:
self.device = cams[self.device_id].__enter__()
self.set_defaults()
self.start_stream()
def start_stream(self):
if self.device is not None:
self.is_streaming = True
self.stream_thread.start()
time.sleep(1)
def thread_stream(self):
while self.is_streaming:
current_frame = self.device.get_frame().as_opencv_image()
h, w, _ = current_frame.shape
self.current_frame = current_frame.reshape((h, w))
self.stream_thread = threading.Thread(target=self.thread_stream, daemon=True)
def stop_stream(self):
if self.device is not None:
self.is_streaming = False
def live_video(self):
if self.device is not None:
window_name = "Allied Vision"
h, w = self.current_frame.shape
w = int(w / self.scale_window)
h = int(h / self.scale_window)
cv2.namedWindow(window_name, cv2.WINDOW_NORMAL)
cv2.resizeWindow(window_name, w, h)
while 1:
cv2.imshow(window_name, self.current_frame)
cv2.waitKey(1)
if cv2.getWindowProperty(window_name, cv2.WND_PROP_VISIBLE) < 1:
break
cv2.destroyAllWindows()
def set_defaults(self):
if self.device is not None:
# Exposure time settings
self.device.ExposureAuto.set(self.auto_exposure)
self.device.ExposureTimeAbs.set(self.exposure_us)
# Gain settings
self.device.GainAuto.set(self.auto_gain)
self.device.Gain.set(self.gain)
# Gamma settings
self.device.Gamma.set(self.gamma)
self.device.AcquisitionMode.set(self.acquisition)
self.device.AcquisitionFrameRateAbs.set(self.fps)
# Try to adjust GeV packet size (available for GigE only)
try:
self.device.GVSPAdjustPacketSize.run()
while not self.device.GVSPAdjustPacketSize.is_done():
pass
except (AttributeError, VimbaFeatureError):
pass
# Color formatting (tries mono first, then color)
cv_formats = intersect_pixel_formats(self.device.get_pixel_formats(), OPENCV_PIXEL_FORMATS)
mono_formats = intersect_pixel_formats(cv_formats, MONO_PIXEL_FORMATS)
color_formats = intersect_pixel_formats(cv_formats, COLOR_PIXEL_FORMATS)
if mono_formats:
self.device.set_pixel_format(mono_formats[0])
elif color_formats:
self.device.set_pixel_format(color_formats[0])
if __name__ == "__main__":
dev = VimbaCam()
dev.live_video()
dev.close()

You need to use thread to run the capture code and pass the frames read via queue. Then the main tkinter application reads the queue and show the frames periodically using .after().
Below is an example based on your posted code:
import threading
from queue import SimpleQueue
import tkinter as tk
from PIL import Image, ImageTk
from vimba import Vimba
def camera_streaming(queue):
global is_streaming
is_streaming = True
print("streaming started")
with Vimba.get_instance() as vimba:
with vimba.get_all_cameras()[0] as camera:
while is_streaming:
frame = camera.get_frame()
frame = frame.as_opencv_image()
im = Image.fromarray(frame)
img = ImageTk.PhotoImage(im)
queue.put(img) # put the capture image into queue
print("streaming stopped")
def start_streaming():
start_btn["state"] = "disabled" # disable start button to avoid running the threaded task more than once
stop_btn["state"] = "normal" # enable stop button to allow user to stop the threaded task
show_streaming()
threading.Thread(target=camera_streaming, args=(queue,), daemon=True).start()
def stop_streaming():
global is_streaming, after_id
is_streaming = False # terminate the streaming thread
if after_id:
lblVideo.after_cancel(after_id) # cancel the showing task
after_id = None
stop_btn["state"] = "disabled" # disable stop button
start_btn["state"] = "normal" # enable start button
# periodical task to show frames in queue
def show_streaming():
global after_id
if not queue.empty():
image = queue.get()
lblVideo.config(image=image)
lblVideo.image = image
after_id = lblVideo.after(20, show_streaming)
queue = SimpleQueue() # queue for video frames
after_id = None
root = tk.Tk()
lblVideo = tk.Label(root, image=tk.PhotoImage(), width=640, height=480)
lblVideo.grid(row=0, column=0, columnspan=2)
start_btn = tk.Button(root, text="Start", width=10, command=start_streaming)
start_btn.grid(row=1, column=0)
stop_btn = tk.Button(root, text="Stop", width=10, command=stop_streaming, state="disabled")
stop_btn.grid(row=1, column=1)
root.mainloop()
Note that I don't have the camera and the SDK installed, the above code may not work for you. I just demonstrate how to use thread, queue and .after().
Below is a testing vimba module (saved as vimba.py) I use to simulate VimbaPython module using OpenCV and a webcam:
import cv2
class Frame:
def __init__(self, frame):
self.frame = frame
def as_opencv_image(self):
return self.frame
class Camera:
def __init__(self, cam_id=0):
self.cap = cv2.VideoCapture(cam_id, cv2.CAP_DSHOW)
def __enter__(self):
return self
def __exit__(self, *args):
self.cap.release()
return self
def get_frame(self):
ret, frame = self.cap.read()
if ret:
return Frame(frame)
class Vimba:
_instance = None
#classmethod
def get_instance(self):
if self._instance is None:
self._instance = Vimba()
return self._instance
def __enter__(self):
return self
def __exit__(self, *args):
return self
def get_all_cameras(self):
return (Camera(),)

I tried to read the frames in openCV and display them in tkinter label. I was able to do so using the below code:
import tkinter as tk
import cv2
from PIL import ImageTk, Image
video_path = "SAMPLE/STORED_VIDEO/PATH"
root = tk.Tk()
base_img = Image.open("PATH/TO/DEFAULT/LABLE/IMAGE")
img_obj = ImageTk.PhotoImage(base_img)
lblVideo = tk.Label(root, image=img_obj)
lblVideo.pack()
cap = cv2.VideoCapture(video_path)
if cap.isOpened():
def show_frame():
_, frame = cap.read()
im = Image.fromarray(frame)
img = ImageTk.PhotoImage(im)
lblVideo.configure(image=img)
lblVideo.image = img
lblVideo.after(1, show_frame) # Need to create callback here
show_frame()
root.mainloop()
Although this doesnot contain the with statement, you can try replacing the after() callback inside the show_frame function itself.

Slide show program, event processing

I need the images to change if the cursor is inside the window without moving, but I managed to make the image changes only if the cursor is moving inside the window, how can I change the code?
from itertools import cycle
import tkinter as tk
from PIL import ImageTk, Image
import glob
image_files = glob.glob("*.jpg")
root = tk.Toplevel()
root.geometry("1600x900")
pictures = cycle((ImageTk.PhotoImage(file=image), image) for image in image_files)
picture_display = tk.Label(root)
picture_display.pack()
def show_slides(event):
img_object, img_name = next(pictures)
root.after(500, picture_display.config(image=img_object))
root.bind("<Motion>", show_slides)
root.mainloop()

You could bind the <Enter> and <Leave> events and use a flag to control the call, followed by using the after method to loop the function.
def show_slides(event=None):
global change_slide
img_object, img_name = next(pictures)
picture_display.config(image=img_object)
change_slide=root.after(500,show_slides)
def stop_slides(event):
root.after_cancel(change_slide)
root.bind("<Enter>", show_slides)
root.bind("<Leave>", stop_slides)
UPDATE
Using a flag might cause multiple calls being scheduled it the events happen during the 500ms delay, you can use after_cancel to terminate it.

You can calculate cursor position in loop and show image if it's located within tkinter window:
import glob
import tkinter as tk
from PIL import ImageTk
from itertools import cycle
class App(object):
def __init__(self):
self.root = tk.Tk()
self.root.geometry('900x600')
self.lbl = tk.Label(self.root)
self.lbl.pack()
files = glob.glob('*.jpg')
self.images = cycle((ImageTk.PhotoImage(file=f), f) for f in files)
self.show()
self.root.mainloop()
def show(self):
abs_coord_x = self.root.winfo_pointerx() - self.root.winfo_rootx()
abs_coord_y = self.root.winfo_pointery() - self.root.winfo_rooty()
if 0 <= abs_coord_x <= self.root.winfo_width() and 0 <= abs_coord_y <= self.root.winfo_height():
img_object, img_name = next(self.images)
self.lbl.config(image=img_object)
self.root.after(1000, self.show)
App()

Displaying multiple independent windows with images in tkinter, and having the main loop exit when they have all been closed

My plotting library needs to be able to show multiple plots at the same time, each of which is represented as a PIL image, and each of which should show up as its own window. The windows should be independent, so closing any one of them should not affect the others, but when all of them have been closed the main loop should exit. This behavior was easy to achieve in qt and wx, but in qt it's proving difficult so far.
Here's the closest I've come so far:
from six.moves import tkinter
from PIL import ImageTk
class Window:
def __init__(self, img):
self.window = tkinter.Toplevel()
self.window.minsize(img.width, img.height)
self.canvas = tkinter.Canvas(self.window, width=img.width, height=img.height)
self.canvas.pack()
self.canvas.configure(background="white")
self.photo = ImageTk.PhotoImage(img)
self.sprite = self.canvas.create_image(0, 0, image=self.photo, anchor=tkinter.NW)
windows = []
for img in imgs:
windows.append(Window(img))
if len(windows) > 0: windows[0].window.mainloop()
This displays an image in each window, and each of those windows can be closed independently. But it also displays an empty root window which needs to be closed for the main loop to exit, and which will cause all windows to close when closed, which is not the behavior I want.
If I replace tkinter.Toplevel() with tkinter.Tk(), then create_image fails for the second window with an obscure "pyimageX does not exist" error message, where X is an incrementing integer.
Will I have to make an invisible root window, and then manually count how many child windows have closed and trigger destruction of the invisible root window when all of them have closed in order to get the behavior I'm looking for? Or is there a simple way to achieve this?
Edit: Just to clarify: My program is not mainly a Tk app. It spends almost all its time doing other stuff, and only temporarily uses Tk in a single function to display some plots. That's why it's important that the main loop exits after the plots have been closed, to the program can resume its normal operation. Think about how show() in matplotlib works for an example of this scenario.

Here is an example of how you might want to do this. This example uses the root window to house a button that will open up all images at the top level.
Make sure you change self.path to your image folder.
import tkinter as tk
import os
class App(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
tk.Button(self, text="Open Images", command=self.open_images).pack()
self.path = ".\RGB"
def open_images(self):
directory = os.fsencode(self.path)
for file in os.listdir(directory):
filename = os.fsdecode(file)
if filename.endswith(".gif"):
print(filename)
top = tk.Toplevel(self)
img = tk.PhotoImage(file="{}\{}".format(self.path, filename))
lbl = tk.Label(top, image=img)
lbl.image = img
lbl.pack()
if __name__ == '__main__':
app = App()
app.mainloop()
Here is my 2nd example where you can hide the root window and when the last top level window is closed the tkinter instance is also destroyed. This is maned with a simple tracking variable.
import tkinter as tk
import os
class App(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
self.top_level_count = 0
self.path = ".\RGB"
self.open_images()
self.withdraw()
def open_images(self):
directory = os.fsencode(self.path)
for file in os.listdir(directory):
filename = os.fsdecode(file)
if filename.endswith(".gif"):
self.top_level_count += 1
image_top(self, self.path, filename)
def check_top_count(self):
print(self.top_level_count)
if self.top_level_count <= 0:
self.destroy()
class image_top(tk.Toplevel):
def __init__(self, controller, path, filename):
tk.Toplevel.__init__(self, controller)
self.controller = controller
self.protocol("WM_DELETE_WINDOW", self.handle_close)
img = tk.PhotoImage(file="{}\{}".format(path, filename))
lbl = tk.Label(self, image=img)
lbl.image = img
lbl.pack()
def handle_close(self):
self.controller.top_level_count -= 1
self.destroy()
self.controller.check_top_count()
if __name__ == '__main__':
app = App()
app.mainloop()

Ok so here's a couple of classes I came up with to solve this problem:
class ImgRoot(tkinter.Tk):
def __init__(self, imgs):
super(ImgRoot, self).__init__()
for i in imgs:
Window(self, i)
self.withdraw()
self.open=True
self.tick()
def tick(self):
if not self.open:
self.destroy()
self.open=False
self.after(100, self.tick)
def checkin(self):
self.open=True
class Window(tkinter.Toplevel):
def __init__(self, root, img):
super(Window, self).__init__()
self.root=root
self.tick()
self.minsize(img.width, img.height)
self.canvas = tkinter.Canvas(self, width=img.width, height=img.height)
self.canvas.pack()
self.canvas.configure(background="white")
self.photo = ImageTk.PhotoImage(img)
self.sprite = self.canvas.create_image(0, 0, image=self.photo, anchor=tkinter.NW)
def tick(self):
self.root.checkin()
self.after(100, self.tick)
The idea here is to create a main class (ImgRoot) which handles the whole thing. Then, every 0.1 seconds (100 miliseconds), it will check if any of the image windows have told it that they are still alive, and, if not, close. The image windows (Windows) do this by setting the ImgRoot's open attribute to True every 0.1 seconds that they are alive. Here is an example usage:
import tkinter
#above classes go here
ImgRoot(imgs) #imgs is a list as defined in your question
tkinter.mainloop()
print('done') #or whatever you want to do next

Multiple Video Display using Tkinter in Python for GUI design

My task is to display a webcam stream and its black&white stream in two different frames on a single GUI using Tkinter on python. I have seen some examples on google, but they are of images not videos as in the link here. Example of image display in 2 panes on a single GUI
I need exactly the same thing but for the real time video through my webcam.

Initial question:
"I am having issues in displaying multiple (2) windows for displaying video frames in a GUI using Tkinter in python. Please help me with a
code for this task."
The initial question mentioned 2 windows so here's a basic example on how to create multiple windows with tkinter:
#import tkinter as tk
import Tkinter as tk
class MainWindow(tk.Tk):
def __init__(self, *args, **kwargs):
#super().__init__()
tk.Tk.__init__(self)
self.title("This is the MainWindow")
self._is_hidden = False
self.window1 = OtherWindow(self, title="window 1")
self.window2 = OtherWindow(self, title="window 2")
def toggle_hide(self):
if self._is_hidden:
self.iconify()
self.deiconify()
else:
self.withdraw()
self._is_hidden = not self._is_hidden
class OtherWindow(tk.Toplevel):
def __init__(self, master, *args, **kwargs):
#super().__init__(master)
tk.Toplevel.__init__(self, master)
if 'title' in kwargs:
self.title(kwargs['title'])
self.hide_main_button = tk.Button(self, text="Hide/Show MainWindow")
self.hide_main_button['command'] = self.master.toggle_hide
self.hide_main_button.pack()
if __name__ == '__main__':
root = MainWindow()
root.mainloop()

from ttk import *
import Tkinter as tk
from Tkinter import *
import cv2
from PIL import Image, ImageTk
import os
import numpy as np
global last_frame #creating global variable
last_frame = np.zeros((480, 640, 3), dtype=np.uint8)
global last_frame2 #creating global variable
last_frame2 = np.zeros((480, 640, 3), dtype=np.uint8)
global cap
cap = cv2.VideoCapture(1)
def show_vid(): #creating a function
if not cap.isOpened(): #checks for the opening of camera
print("cant open the camera")
flag, frame = cap.read()
frame = cv2.resize(frame,(400,500))
if flag is None:
print "Major error!"
elif flag:
global last_frame
last_frame = frame.copy()
global last_frame2
last_frame2 = frame.copy()
pic = cv2.cvtColor(last_frame, cv2.COLOR_BGR2RGB) #we can change the display color of the frame gray,black&white here
img = Image.fromarray(pic)
imgtk = ImageTk.PhotoImage(image=img)
lmain.imgtk = imgtk
lmain.configure(image=imgtk)
lmain.after(10, show_vid)
def show_vid2():
pic2 = cv2.cvtColor(last_frame2, cv2.COLOR_BGR2GRAY)
img2 = Image.fromarray(pic2)
img2tk = ImageTk.PhotoImage(image=img2)
lmain2.img2tk = img2tk
lmain2.configure(image=img2tk)
lmain2.after(10, show_vid2)
if __name__ == '__main__':
root=tk.Tk() #assigning root variable for Tkinter as tk
lmain = tk.Label(master=root)
lmain2 = tk.Label(master=root)
#lmain.Frame= Frame(width=768, height=576)
#framex.grid(column=3,rowspan=2,padx=5, pady=5)
lmain.pack(side = LEFT)
lmain2.pack(side = RIGHT)
root.title("Fire Alarm Detector") #you can give any title
root.geometry("900x700+100+10") #size of window , x-axis, yaxis
exitbutton = Button(root, text='Quit',fg="red",command= root.destroy).pack(side = BOTTOM,)
show_vid()
show_vid2()
root.mainloop() #keeps the application in an infinite loop so it works continuosly
cap.release()

import tkinter
import PIL.Image
import PIL.ImageTk
import cv2
class App:
def __init__(self, window, video_source1, video_source2):
self.window = window
self.window.title("KEC MEDIA PLAYER")
self.video_source1 = video_source1
self.video_source2 = video_source2
self.photo1 = ""
self.photo2 = ""
# open video source
self.vid1 = MyVideoCapture(self.video_source1, self.video_source2)
# Create a canvas that can fit the above video source size
self.canvas1 = tkinter.Canvas(window, width=500, height=500)
self.canvas2 = tkinter.Canvas(window, width=500, height=500)
self.canvas1.pack(padx=5, pady=10, side="left")
self.canvas2.pack(padx=5, pady=60, side="left")
# After it is called once, the update method will be automatically called every delay milliseconds
self.delay = 15
self.update()
self.window.mainloop()
def update(self):
# Get a frame from the video source
ret1, frame1, ret2, frame2 = self.vid1.get_frame
if ret1 and ret2:
self.photo1 = PIL.ImageTk.PhotoImage(image=PIL.Image.fromarray(frame1))
self.photo2 = PIL.ImageTk.PhotoImage(image=PIL.Image.fromarray(frame2))
self.canvas1.create_image(0, 0, image=self.photo1, anchor=tkinter.NW)
self.canvas2.create_image(0, 0, image=self.photo2, anchor=tkinter.NW)
self.window.after(self.delay, self.update)
class MyVideoCapture:
def __init__(self, video_source1, video_source2):
# Open the video source
self.vid1 = cv2.VideoCapture(video_source1)
self.vid2 = cv2.VideoCapture(video_source2)
if not self.vid1.isOpened():
raise ValueError("Unable to open video source", video_source1)
#property
def get_frame(self):
ret1 = ""
ret2 = ""
if self.vid1.isOpened() and self.vid2.isOpened():
ret1, frame1 = self.vid1.read()
ret2, frame2 = self.vid2.read()
frame1 = cv2.resize(frame1, (500, 500))
frame2 = cv2.resize(frame2, (500, 500))
if ret1 and ret2:
# Return a boolean success flag and the current frame converted to BGR
return ret1, cv2.cvtColor(frame1, cv2.COLOR_BGR2RGB), ret2, cv2.cvtColor(frame2, cv2.COLOR_BGR2RGB)
else:
return ret1, None, ret2, None
else:
return ret1, None, ret2, None
# Release the video source when the object is destroyed
def __del__(self):
if self.vid1.isOpened():
self.vid1.release()
if self.vid2.isOpened():
self.vid2.release()
def callback():
global v1,v2
v1=E1.get()
v2=E2.get()
if v1 == "" or v2 == "":
L3.pack()
return
initial.destroy()
v1 = ""
v2 = ""
initial = tkinter.Tk()
initial.title("KEC MEDIA PLAYER")
L0 = tkinter.Label(initial, text="Enter the full path")
L0.pack()
L1 = tkinter.Label(initial, text="Video 1")
L1.pack()
E1 = tkinter.Entry(initial, bd =5)
E1.pack()
L2 = tkinter.Label(initial, text="Video 2")
L2.pack()
E2 = tkinter.Entry(initial, bd =5)
E2.pack()
B = tkinter.Button(initial, text ="Next", command = callback)
B.pack()
L3 = tkinter.Label(initial, text="Enter both the names")
initial.mainloop()
# Create a window and pass it to the Application object
App(tkinter.Tk(),v1, v2)
This code works under normal circumstances but I haven't handled situations where one video ends and the other is still playing. Also, the audio has not been handled in this code.
I created two canvases in the same window and ran the video as a series of images. I have resized the video to fit a constant canvas size but you can change the canvas size to fit the video if you want.
You can change the source to be from your webcam.

python: tkinter to display video from webcam and do a QR scan

I have been trying to create a tkinter top level window that streams video form webcam and do a QR scan. I got this QR scan code from SO and another code that just updates images from webcam instead of streaming the video on a tkinter label.
and i tried to combine these both so that a toplevel window with a label updating image from webcam and a close button to close the toplevel window. And while it streams the images, it can scan for QR code and if a scan is successful, the webcam and the toplevel window gets closed.
here is what i tried.
import cv2
import cv2.cv as cv
import numpy
import zbar
import time
import threading
import Tkinter
from PIL import Image, ImageTk
class BarCodeScanner(threading.Thread, Tkinter.Toplevel):
def __init__(self):
# i made this as a global variable so i can access this image
# outside ie,. beyond the thread to update the image on to the tkinter window
global imgtk
imgtk = None
threading.Thread.__init__(self)
self.WINDOW_NAME = 'Camera'
self.CV_SYSTEM_CACHE_CNT = 5 # Cv has 5-frame cache
self.LOOP_INTERVAL_TIME = 0.2
cv.NamedWindow(self.WINDOW_NAME, cv.CV_WINDOW_NORMAL)
self.cam = cv2.VideoCapture(-1)
self.confirm = 0
def scan(self, aframe):
imgray = cv2.cvtColor(aframe, cv2.COLOR_BGR2GRAY)
# to show coloured image, as from the other code mentioned in the other code
imgcol = cv2.cvtColor(aframe, cv2.COLOR_BGR2RGBA)
imgcol_array = Image.fromarray(imgcol)
imgtk = ImageTk.PhotoImage(image=imgcol_array)
raw = str(imgray.data)
scanner = zbar.ImageScanner()
scanner.parse_config('enable')
width = int(self.cam.get(cv.CV_CAP_PROP_FRAME_WIDTH))
height = int(self.cam.get(cv.CV_CAP_PROP_FRAME_HEIGHT))
imageZbar = zbar.Image(width, height,'Y800', raw)
scanner.scan(imageZbar)
for symbol in imageZbar:
print 'decoded', symbol.type, 'symbol', '"%s"' % symbol.data
return symbol.data
def run(self):
self.datalst = []
print 'BarCodeScanner run', time.time()
while True:
for i in range(0,self.CV_SYSTEM_CACHE_CNT):
self.cam.read()
img = self.cam.read()
self.data = self.scan(img[1])
cv2.imshow(self.WINDOW_NAME, img[1])
cv.WaitKey(1)
time.sleep(self.LOOP_INTERVAL_TIME)
if self.data:
self.datalst.append(self.data)
# i have added this section so that it waits for scan
# if a scan is made it and if gets same value after 2 scans
# it has to stop webcam
if len(self.datalst) == 2 and len(set(self.datalst)) <= 1:
# I want to close the webcam before closing the toplevel window
#self.cam.release()
#cv2.destroyAllWindows()
break
self.cam.release()
def Video_Window():
video_window = Tkinter.Toplevel()
video_window.title('QR Scan !!')
img_label = Tkinter.Label(video_window)
img_label.pack(side=Tkinter.TOP)
close_button = Tkinter.Button(video_window, text='close', command = video_window.destroy)
close_button.pack(side=Tkinter.TOP)
def update_frame():
global imgtk
img_label.configure(image=imgtk)
img_label.after(10,update_frame)
update_frame()
def main():
root = Tkinter.Tk()
button_scanQr = Tkinter.Button(root, text='QR Scan', command=start_scan)
button_scanQr.pack()
root.mainloop()
def start_scan():
scanner = BarCodeScanner()
scanner.start()
Video_Window()
#scanner.join()
main()
Problem is,
I actually wanted to display the video on the Toplevel window, not the OpenCV window
at the same time do a QR Scan,if a read is sucessfull, the Toplevel window should close without abruptly closing webcam(because, when i try to use self.cam.release() or cv2.destroyAllWindows() my webcams lights or on even if i forcefully terminate the programs compilation).
Now what i get is a separate window created by OpenCV that streams video inside. But i don’t want that window, instead i want the video to be displayed on the tkinter's toplevel window. also when there is a sucessfull read, the webcam stucks at the final image it reads.
i tried to remove the line that was responsible for OpenCV window, inside the run method of BarcodeScanner class
cv2.imshow(self.WINDOW_NAME, img[1])
it still showed up with a different window with no output, and if i try to close that window, it created another one similar and recursively.
UPDATE:
As i noticed i made some silly mistakes without understanding of some lines in cv2, i made some change on the code by adding the toplevel window code into the run method of the class(im not sure if this is a right way).
import cv2
import cv2.cv as cv
import numpy
import zbar
import time
import threading
import Tkinter
from multiprocessing import Process, Queue
from Queue import Empty
from PIL import Image, ImageTk
class BarCodeScanner(threading.Thread, Tkinter.Toplevel):
def __init__(self):
threading.Thread.__init__(self)
#self.WINDOW_NAME = 'Camera'
self.CV_SYSTEM_CACHE_CNT = 5 # Cv has 5-frame cache
self.LOOP_INTERVAL_TIME = 0.2
#cv.NamedWindow(self.WINDOW_NAME, cv.CV_WINDOW_NORMAL)
self.cam = cv2.VideoCapture(-1)
# check if webcam device is free
self.proceede = self.cam.isOpened()
if not self.proceede:
return
self.confirm = 0
def scan(self, aframe):
imgray = cv2.cvtColor(aframe, cv2.COLOR_BGR2GRAY)
raw = str(imgray.data)
scanner = zbar.ImageScanner()
scanner.parse_config('enable')
width = int(self.cam.get(cv.CV_CAP_PROP_FRAME_WIDTH))
height = int(self.cam.get(cv.CV_CAP_PROP_FRAME_HEIGHT))
imageZbar = zbar.Image(width, height,'Y800', raw)
scanner.scan(imageZbar)
for symbol in imageZbar:
print 'decoded', symbol.type, 'symbol', '"%s"' % symbol.data
return symbol.data
def run(self):
if not self.proceede:
return
def show_frame():
_, img = self.cam.read()
img = cv2.flip(img,1)
cv2image = cv2.cvtColor(img, cv2.COLOR_BGR2RGBA)
img = Image.fromarray(cv2image)
imgtk = ImageTk.PhotoImage(image=img)
img_label.imgtk = imgtk
img_label.configure(image=imgtk)
video_window.after(250, show_frame)
def destroy_video_window():
self.cam.release()
video_window.destroy()
# Toplevel GUI
video_window = Tkinter.Toplevel()
video_window.title('QR Scan !!')
img_label = Tkinter.Label(video_window)
img_label.pack(side=Tkinter.TOP)
close_button = Tkinter.Button(video_window, text='close', command = destroy_video_window)
close_button.pack(side=Tkinter.RIGHT)
show_frame()
self.datalst = []
print 'BarCodeScanner run', time.time()
while True:
for i in range(0,self.CV_SYSTEM_CACHE_CNT):
self.cam.read()
img = self.cam.read()
self.data = self.scan(img[1])
time.sleep(self.LOOP_INTERVAL_TIME)
if self.data:
self.datalst.append(self.data)
if len(self.datalst) == 2 and len(set(self.datalst)) <= 1:
video_window.destroy()
break
self.cam.release()
def main():
root = Tkinter.Tk()
button_scanQr = Tkinter.Button(root, text='QR Scan', command=scaner)
button_scanQr.pack()
root.mainloop()
def scaner():
scanner = BarCodeScanner()
scanner.start()
main()
now, I can get the image on the Toplevel window, But i dont know how to close the webcam.
condition 1: when i show a QR code to scan, it reads it successfully and webcam quits without any error.
condition 2: when i click the close button on the toplevel window(say if user doesn't want to do any scan and just want to close the webcam) i get error saying
libv4l2: error dequeuing buf: Invalid argument
VIDIOC_DQBUF: Invalid argument
select: Bad file descriptor
VIDIOC_DQBUF: Bad file descriptor
select: Bad file descriptor
VIDIOC_DQBUF: Bad file descriptor
Segmentation fault (core dumped)
I am writing this application for Linux, Mac and Windows machine. How can i close or terminate the webcam safely.

Your program has two threads, the main thread and the worker thread that reads frames from the camera. When the close button is clicked, it happens in the main thread. After self.cam.release() the object self.cam is probably in an unusable state, and when a method of self.cam is called by the worker thread, there may be some trouble. Maybe the implementation of cv2.VideoCapture is faulty and it should throw some exception when that happens.
Accessing tkinter widgets from other thread than the main thread may also cause problems.
For clean program termination, creating an instance of threading.Event and then checking for event.is_set() at some point in the work thread could work. For example
def destroy_video_window():
self.stop_event.set()
video_window.destroy()
and then in the worker thread
while True:
if self.stop_event.is_set():
break
for i in range(0, self.CV_SYSTEM_CACHE_CNT):
self.cam.read()
There are several things that could be done in other way, the following is a modified version of the code. It avoids calling tkinter methods from other thread than the main thread, event_generate() being the only tkinter method called by the worker thread. Explicit polling is avoided by emitting virtual events, for example <<ScannerQuit>>, that are placed in the tkinter event queue.
import cv2
import cv2.cv as cv
import zbar
import time
import threading
import Tkinter as tk
from PIL import Image, ImageTk
class Scanner(object):
def __init__(self, handler, *args, **kw):
self.thread = threading.Thread(target=self.run)
self.handler = handler
self.CV_SYSTEM_CACHE_CNT = 5 # Cv has 5-frame cache
self.LOOP_INTERVAL_TIME = 0.2
self.cam = cv2.VideoCapture(-1)
self.scanner = zbar.ImageScanner()
self.scanner.parse_config('enable')
self.cam_width = int(self.cam.get(cv.CV_CAP_PROP_FRAME_WIDTH))
self.cam_height = int(self.cam.get(cv.CV_CAP_PROP_FRAME_HEIGHT))
self.last_symbol = None
def start(self):
self.thread.start()
def scan(self, aframe):
imgray = cv2.cvtColor(aframe, cv2.COLOR_BGR2GRAY)
raw = str(imgray.data)
image_zbar = zbar.Image(self.cam_width, self.cam_height, 'Y800', raw)
self.scanner.scan(image_zbar)
for symbol in image_zbar:
return symbol.data
def run(self):
print 'starting scanner'
while True:
if self.handler.need_stop():
break
# explanation for this in
# http://stackoverflow.com/a/35283646/5781248
for i in range(0, self.CV_SYSTEM_CACHE_CNT):
self.cam.read()
img = self.cam.read()
self.handler.send_frame(img)
self.data = self.scan(img[1])
if self.handler.need_stop():
break
if self.data is not None and (self.last_symbol is None
or self.last_symbol <> self.data):
# print 'decoded', symbol.type, 'symbol', '"%s"' % symbol.data
self.handler.send_symbol(self.data)
self.last_symbol = self.data
time.sleep(self.LOOP_INTERVAL_TIME)
self.cam.release()
class ScanWindow(tk.Toplevel):
def __init__(self, parent, gui, *args, **kw):
tk.Toplevel.__init__(self, master=parent, *args, **kw)
self.parent = parent
self.gui = gui
self.scanner = None
self.lock = threading.Lock()
self.stop_event = threading.Event()
self.img_label = tk.Label(self)
self.img_label.pack(side=tk.TOP)
self.close_button = tk.Button(self, text='close', command=self._stop)
self.close_button.pack()
self.bind('<Escape>', self._stop)
parent.bind('<<ScannerFrame>>', self.on_frame)
parent.bind('<<ScannerEnd>>', self.quit)
parent.bind('<<ScannerSymbol>>', self.on_symbol)
def start(self):
self.frames = []
self.symbols = []
class Handler(object):
def need_stop(self_):
return self.stop_event.is_set()
def send_frame(self_, frame):
self.lock.acquire(True)
self.frames.append(frame)
self.lock.release()
self.parent.event_generate('<<ScannerFrame>>', when='tail')
def send_symbol(self_, data):
self.lock.acquire(True)
self.symbols.append(data)
self.lock.release()
self.parent.event_generate('<<ScannerSymbol>>', when='tail')
self.stop_event.clear()
self.scanner = Scanner(Handler())
self.scanner.start()
self.deiconify()
def _stop(self, *args):
self.gui.stop()
def stop(self):
if self.scanner is None:
return
self.stop_event.set()
self.frames = []
self.symbols = []
self.scanner = None
self.iconify()
def quit(self, *args):
self.parent.event_generate('<<ScannerQuit>>', when='tail')
def on_symbol(self, *args):
self.lock.acquire(True)
symbol_data = self.symbols.pop(0)
self.lock.release()
print 'symbol', '"%s"' % symbol_data
self.after(500, self.quit)
def on_frame(self, *args):
self.lock.acquire(True)
frame = self.frames.pop(0)
self.lock.release()
_, img = frame
img = cv2.flip(img, 1)
cv2image = cv2.cvtColor(img, cv2.COLOR_BGR2RGBA)
img = Image.fromarray(cv2image)
imgtk = ImageTk.PhotoImage(image=img)
self.img_label.imgtk = imgtk
self.img_label.configure(image=imgtk)
class GUI(object):
def __init__(self, root):
self.root = root
self.scan_window = ScanWindow(self.root, self)
self.scan_window.iconify()
self.root.title('QR Scan !!')
self.lframe = tk.Frame(self.root)
self.lframe.pack(side=tk.TOP)
self.start_button = tk.Button(self.lframe, text='start', command=self.start)
self.start_button.pack(side=tk.LEFT)
self.stop_button = tk.Button(self.lframe, text='stop', command=self.stop)
self.stop_button.configure(state='disabled')
self.stop_button.pack(side=tk.LEFT)
self.close_button = tk.Button(self.root, text='close', command=self.quit)
self.close_button.pack(side=tk.TOP)
self.root.bind('<<ScannerQuit>>', self.stop)
self.root.bind('<Control-s>', self.start)
self.root.bind('<Control-q>', self.quit)
self.root.protocol('WM_DELETE_WINDOW', self.quit)
def start(self, *args):
self.start_button.configure(state='disabled')
self.scan_window.start()
self.stop_button.configure(state='active')
def stop(self, *args):
self.scan_window.stop()
self.start_button.configure(state='active')
self.stop_button.configure(state='disabled')
def quit(self, *args):
self.scan_window.stop()
self.root.destroy()
def main():
root = tk.Tk()
gui = GUI(root)
root.mainloop()
main()