kivy and opencv work together demo

kivy_cv.py

# coding:utf-8
from kivy.app import App
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
import cv2


class KivyCamera(Image):
    def __init__(self, capture, fps, **kwargs):
        super(KivyCamera, self).__init__(**kwargs)
        self.capture = capture
        Clock.schedule_interval(self.update, 1.0 / fps)

    def update(self, dt):
        ret, frame = self.capture.read()
        if ret:
            # convert it to texture
            buf1 = cv2.flip(frame, 0)
            buf = buf1.tostring()
            image_texture = Texture.create(
                size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
            image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
            # display image from the texture
            self.texture = image_texture


class CamApp(App):
    def build(self):
        self.capture = cv2.VideoCapture(1)
        self.my_camera = KivyCamera(capture=self.capture, fps=30)
        return self.my_camera

    def on_stop(self):
        #without this, app will not exit even if the window is closed
        self.capture.release()


if __name__ == '__main__':
    CamApp().run()

Thank you for this amazing OpenCV example!
However, I have an issue for new android versions.
I got the following error when starting the .apk on Android 8.0:

Detected problems with app native libraries
(please consult log to details):
Libnative_camera_r4.4.0.so: unauthorized access to "libutils.so"

On my mind, the cause is security options of new Android, but I couldn't find workaround yet.
Did anyone solve similar problem?

thank you bro

It works by itself but i have no clue on how to add it to a layout im not sure what im doing wrong

@da0c after connecting your phone (wich is in debugging mode) to the computer your computer you will get notification on your phone there you must accept the connection

after building this code with buildozer for android, when I open the App it shows a black screen with a small square in the left corner of the screen. Anyone can help me? I believe the camera is not being accessed. In buildozer.spec I gave the App permission to access the camera.

@rafaelscariot have u found the solution?

after building this code with buildozer for android, when I open the App it shows a black screen with a small square in the left corner of the screen. Anyone can help me? I believe the camera is not being accessed. In buildozer.spec I gave the App permission to access the camera.

I have the same problem when I first tried the example. I then change cv2.VideoCapture(1) to cv2.VideoCapture(0) and it works.
If it doesn't, try cv2.VideoCapture(-1). Hope this helps.

after building this code with buildozer for android, when I open the App it shows a black screen with a small square in the left corner of the screen. Anyone can help me? I believe the camera is not being accessed. In buildozer.spec I gave the App permission to access the camera.

I have the same problem when I first tried the example. I then change cv2.VideoCapture(1) to cv2.VideoCapture(0) and it works.
If it doesn't, try cv2.VideoCapture(-1). Hope this helps.

Nope, I tried both 0 and -1, but doesn't work

can we run thin on mac
actually its coming blank window when i m running in vscode on mac ios

after building this code with buildozer for android, when I open the App it shows a black screen with a small square in the left corner of the screen. Anyone can help me? I believe the camera is not being accessed. In buildozer.spec I gave the App permission to access the camera.

I have the same problem when I first tried the example. I then change cv2.VideoCapture(1) to cv2.VideoCapture(0) and it works.
If it doesn't, try cv2.VideoCapture(-1). Hope this helps.

Nope, I tried both 0 and -1, but doesn't work
Hi! could you solve the problem?...I have the same issue

did anyone found the solution for black screen.?

Here's my modification on it with just a few lines of code added, which works seamlessly from the original. Now the video feed is used to scan faces.

You can download the haarcascades here:
https://www.murtazahassan.com/wp-content/uploads/2020/03/haarcascades.zip

Place your .py and that folder in the same location and just edit the source destination in cv2.CascadeClassifer()

`
# coding:utf-8
from kivy.app import App
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
import cv2

class KivyCamera(Image):
    def __init__(self, capture, fps, **kwargs):
        super(KivyCamera, self).__init__(**kwargs)
        self.capture = capture
        Clock.schedule_interval(self.update, 1.0 / fps)

    def update(self, dt):
        faceCascade = cv2.CascadeClassifier("Resources/haarcascades/haarcascade_frontalface_default.xml")  # added

        ret, frame = self.capture.read()
        if ret:

            frameGray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)  # added
            faces = faceCascade.detectMultiScale(frameGray, 1.1, 4)  # added

            for (x, y, w, h) in faces:  # added
                cv2.rectangle(frame, (x, y), (x + w, y + h), (255, 0, 0), 2)  # added

            # convert it to texture
            buf1 = cv2.flip(frame, 0)
            buf = buf1.tostring()
            image_texture = Texture.create(
                size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
            image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
            # display image from the texture
            self.texture = image_texture


class CamApp(App):
    def build(self):
        self.capture = cv2.VideoCapture(0)
        self.my_camera = KivyCamera(capture=self.capture, fps=30)
        return self.my_camera

    def on_stop(self):
        #without this, app will not exit even if the window is closed
        self.capture.release()


if __name__ == '__main__':
    CamApp().run()

`

Now time to figure out how to make it work with the Launcher lol

Here's my modification on it with just a few lines of code added, which works seamlessly from the original. Now the video feed is used to scan faces.

You can download the haarcascades here:
https://www.murtazahassan.com/wp-content/uploads/2020/03/haarcascades.zip

Place your .py and that folder in the same location and just edit the source destination in cv2.CascadeClassifer()

`

coding:utf-8

from kivy.app import App
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
import cv2

class KivyCamera(Image):
    def __init__(self, capture, fps, **kwargs):
        super(KivyCamera, self).__init__(**kwargs)
        self.capture = capture
        Clock.schedule_interval(self.update, 1.0 / fps)

    def update(self, dt):
        faceCascade = cv2.CascadeClassifier("Resources/haarcascades/haarcascade_frontalface_default.xml")  # added

        ret, frame = self.capture.read()
        if ret:

            frameGray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)  # added
            faces = faceCascade.detectMultiScale(frameGray, 1.1, 4)  # added

            for (x, y, w, h) in faces:  # added
                cv2.rectangle(frame, (x, y), (x + w, y + h), (255, 0, 0), 2)  # added

            # convert it to texture
            buf1 = cv2.flip(frame, 0)
            buf = buf1.tostring()
            image_texture = Texture.create(
                size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
            image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
            # display image from the texture
            self.texture = image_texture


class CamApp(App):
    def build(self):
        self.capture = cv2.VideoCapture(0)
        self.my_camera = KivyCamera(capture=self.capture, fps=30)
        return self.my_camera

    def on_stop(self):
        #without this, app will not exit even if the window is closed
        self.capture.release()


if __name__ == '__main__':
    CamApp().run()

`

Now time to figure out how to make it work with the Launcher lol

Is it working in android?

Nope. Trying to figure that out though.

@DunZek

Nope. Trying to figure that out though.

Hi is it working with kivy launcher without buildozer

after building this code with buildozer for android, when I open the App it shows a black screen with a small square in the left corner of the screen. Anyone can help me? I believe the camera is not being accessed. In buildozer.spec I gave the App permission to access the camera.

I have the same problem when I first tried the example. I then change cv2.VideoCapture(1) to cv2.VideoCapture(0) and it works.
If it doesn't, try cv2.VideoCapture(-1). Hope this helps.

Thanks for that.

Has anyone managed to actually make it work ? I have been trying a lot but without success and it goes the same with opening video files with cv2.VideoCapture.

@DunZek @eva-ave @rafaelscariot @lakshit77
Have you managed solve black screen problem ? I created apk file with buildozer but I have the black screen with the white square in left corner.

@DunZek @eva-ave @rafaelscariot @lakshit77
Have you managed solve black screen problem ? I created apk file with buildozer but I have the black screen with the white square in left corner.

I am facing the same problem please help

how to increase capture display frame size

@DunZek I tried your code it gave me a full white screen, I also tried running and debugging in the android studio it does not have any error.. where might be the problem.

@DunZek @eva-ave @rafaelscariot @lakshit77
Have you managed solve black screen problem ? I created apk file with buildozer but I have the black screen with the white square in left corner.

I am facing the same problem please help

This guy got the solution:
https://stackoverflow.com/questions/61122285/kivy-camera-application-with-opencv-in-android-shows-black-screen

I don't know if anyone is still interested in this, but since it took me three days to get there, here is a "minimal" example of OpenCV VideoCapture displaying frame by frame on Android:

https://github.com/4ndr3aR/kivy-opencv-demo

I don't know if anyone is still interested in this, but since it took me three days to get there, here is a "minimal" example of OpenCV VideoCapture displaying frame by frame on Android:

https://github.com/4ndr3aR/kivy-opencv-demo

Really Great.Helped me a lot

I found this video tutorial about building kivy apps with opencv codes using Buildozer, it worked for me. I've tried using some simple functions of opencv and some other libraries as well and worked like a charm. If you face some errors I recommend using logcat filter to troubleshoot:
https://www.youtube.com/watch?v=c4tuSxSoERY&t=245s
Here is a simple working code using opencv to display the phone's camera image on the screen:
https://stackoverflow.com/questions/61122285/kivy-camera-application-with-opencv-in-android-shows-black-screen

Nope. Trying to figure that out though.

@DunZek have you figured this one out?

Has anyone succeeded in making an Android camera with Python using OpenCv?
Below is the code that succeeded in another way.

-- below --

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
import time

from android.permissions import request_permissions, Permission
request_permissions([Permission.CAMERA])

Builder.load_string('''
:
orientation: 'vertical'
Camera:
id: camera
resolution: (1280, 720)
play: False
ToggleButton:
text: 'Play'
on_press: camera.play = not camera.play
size_hint_y: None
height: '48dp'
Button:
text: 'Capture'
size_hint_y: None
height: '48dp'
on_press: root.capture()
''')

class CameraClick(BoxLayout):
def capture(self):
camera = self.ids['camera']
timestr = time.strftime("%Y%m%d_%H%M%S")
camera.export_to_png("IMG_{}.png".format(timestr))
print("Captured")

class TestCamera(App):
def build(self):
return CameraClick()

TestCamera().run()

I tried running it on a Raspberry Pi and it runs pretty slow. Do you have any optimizations for that?

Threads?

I don't know if anyone is still interested in this, but since it took me three days to get there, here is a "minimal" example of OpenCV VideoCapture displaying frame by frame on Android:

https://github.com/4ndr3aR/kivy-opencv-demo

I couldn't get this to work. The code ran ok but only for one frame after which the Kivy window closed.