Three issues on Android

[RobertFlatt]

1. App crashes if index=1 , I was expecting the selfie camera; index = 0 works as expected.
2. How to release and attach the camera during on_pause() and on_resume() events ?
3. on_camera_ready() is not called because on_index() is not called by default.

Despite the issues, the code is a joy to read. :)

Example code (not as pretty as I would like because no on_camera_ready) , and log for the first issue follow:

#!/usr/bin/env python
from kivy.app import App
from kivy.lang import Builder
from kivy.utils import platform
from kivy.clock import Clock
from os.path import isdir
from os import mkdir
try:
    from android.permissions import request_permissions, check_permission, \
        Permission
    from android.storage import primary_external_storage_path
except:
    pass

kv = """
#:import XCamera kivy_garden.xcamera.XCamera
FloatLayout:
    orientation: 'vertical'
    XCamera:
        id: xcamera
        on_picture_taken: app.picture_taken(*args)
        on_camera_ready: app.camera_ready()
    BoxLayout:
        orientation: 'horizontal'
        size_hint: 1, None
        height: sp(50)
        Button:
            text: 'Set landscape'
            on_release: xcamera.force_landscape()
        Button:
            text: 'Restore orientation'
            on_release: xcamera.restore_orientation()
"""

class CameraApp(App):
    def build(self):
        return Builder.load_string(kv)

    def on_start(self):
        if platform == 'android':
            # ISSUE 1 :
            # Crash when index =1 , index = 0 is OK
            self.root.ids.xcamera.index = 0
            request_permissions([Permission.WRITE_EXTERNAL_STORAGE,
                                 Permission.CAMERA],
                                self.setup_storage)
            self.setup_storage([],[])

    # ISSUE 2 : how to open and close camera ?
    def on_pause(self):
        return True

    def on_resume(self):
        pass

    def camera_ready(self):
        # In kv above     on_camera_ready: app.camera_ready()
        # ISSUE 3 :
        # This is never called because on_index is not called by default
        pass
        
    def setup_storage(self,permissions,grants):
        if platform == 'android':
            if check_permission(Permission.WRITE_EXTERNAL_STORAGE):
                path = join(primary_external_storage_path(),'Pictures')
                if not isdir(path):
                    mkdir(path)
                path = join(path,'Xcamera')
                if not isdir(path):
                    mkdir(path)
                self.root.ids.xcamera.directory = path
            if check_permission(Permission.CAMERA):
                # One sec hack because on_camera_ready() isnt called
                Clock.schedule_once(self.force_landscape,1)

    def force_landscape(self,dt):
        # Force long edge of image to be parallel to long edge of screen.
        # This is independent of the orientation of the screen in the world.
        # At least that is what happens on my Pixel 3
        self.root.ids.xcamera.force_landscape()

    def picture_taken(self, obj, filename):
        print('Picture taken and saved to {}'.format(filename))

def main():
    CameraApp().run()


if __name__ == '__main__':
    main()

Crash log

07-27 13:43:50.324 31415 31444 I python  : [INFO   ] [Base        ] Leaving application in progress...
07-27 13:43:50.324 31415 31444 I python  :  Traceback (most recent call last):
07-27 13:43:50.324 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/app/main.py", line 91, in <module>
07-27 13:43:50.325 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/app/main.py", line 87, in main
07-27 13:43:50.325 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/app.py", line 855, in run
07-27 13:43:50.325 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/base.py", line 504, in runTouchApp
07-27 13:43:50.325 26747 26747 W ActivityThread: handleWindowVisibility: no activity for token android.os.BinderProxy@79e1678
07-27 13:43:50.325 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/core/window/window_sdl2.py", line 747, in mainloop
07-27 13:43:50.326 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/core/window/window_sdl2.py", line 479, in _mainloop
07-27 13:43:50.326 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/base.py", line 339, in idle
07-27 13:43:50.326 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/clock.py", line 591, in tick
07-27 13:43:50.326 31415 31444 I python  :    File "kivy/_clock.pyx", line 384, in kivy._clock.CyClockBase._process_events
07-27 13:43:50.326 31415 31444 I python  :    File "kivy/_clock.pyx", line 414, in kivy._clock.CyClockBase._process_events
07-27 13:43:50.326 31415 31444 I python  :    File "kivy/_clock.pyx", line 412, in kivy._clock.CyClockBase._process_events
07-27 13:43:50.327 31415 31444 I python  :    File "kivy/_clock.pyx", line 167, in kivy._clock.ClockEvent.tick
07-27 13:43:50.327 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/core/camera/camera_android.py", line 155, in _update
07-27 13:43:50.327 31415 31444 I python  :    File "kivy/_event.pyx", line 703, in kivy._event.EventDispatcher.dispatch
07-27 13:43:50.327 31415 31444 I python  :    File "kivy/_event.pyx", line 1214, in kivy._event.EventObservers.dispatch
07-27 13:43:50.328 31415 31444 I python  :    File "kivy/_event.pyx", line 1138, in kivy._event.EventObservers._dispatch
07-27 13:43:50.328 31415 31415 V SDL     : onWindowFocusChanged(): false
07-27 13:43:50.328 31415 31444 I python  :    File "/home/bobf/ex/xcam/.buildozer/android/platform/build-arm64-v8a/build/python-installs/xcam/kivy/uix/camera.py", line 111, in _camera_loaded
07-27 13:43:50.328 31415 31444 I python  :  AttributeError: 'NoneType' object has no attribute 'size'
07-27 13:43:50.328 31415 31444 I python  : Python for android ended.

[RobertFlatt]

I was able to address issue 3 (I think) but I still can't pause/resume or access a camera other than 0.
Even removing and replacing the xcamera widget doesn't address pause/resume.

Forcing an exit on_pause is a sort of workaround for issue 2

Resume, and index=1 are (I think) basic functionality, so I must be missing something basic.
Anybody have any suggestions?

#!/usr/bin/env python
from kivy.app import App
from kivy.lang import Builder
from kivy.utils import platform
from kivy.clock import Clock
from kivy.uix.floatlayout import FloatLayout
from kivy_garden.xcamera import XCamera
from os.path import isdir
from os import mkdir
try:
    from android.permissions import request_permission, check_permission
    from android.permissions import Permission
    from android.storage import primary_external_storage_path
    from jnius import autoclass
    HardwareCamera = autoclass('android.hardware.Camera')
except:
    pass

class CameraApp(App):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.platform_camera = None
        self.platform_camera_paused = False

    def build(self):
        self.xcamera = XCamera()
        self.xcamera.on_picture_taken = self.picture_taken
        self.xcamera._camera.bind(on_load=self.camera_loaded)
        self.layout = FloatLayout()
        self.layout.add_widget(self.xcamera)
        return self.layout

    def on_start(self):
        if platform == 'android':
            if HardwareCamera.getNumberOfCameras() > 1:
                # ISSUE 1 : how to select the other camera ?
                pass
            request_permission(Permission.WRITE_EXTERNAL_STORAGE)

    # ISSUE 2 : how to open and close camera ?
    def on_pause(self):
        if platform == 'android':
            if self.platform_camera:
                # Ignore any on_pause before the camera is loaded
                # and ignore the pair'd on_resume
                '''
                # Try: Remove widget 
                self.layout.remove_widget(self.xcamera)
                self.xcamera = None
                Builder.unload_file('xcamera.kv') 
                '''
                ''' 
                # Try: Disconnect camera
                self.platform_camera.stop()
                self.platform_camera._release_camera()
                '''
                self.platform_camera_paused = True
                # This is a work around, requires multiple taps to 'resume'
                return False
        return True

    def on_resume(self):
        if platform == 'android':
            if self.platform_camera_paused:
                '''
                # Try: Recreate widget - black screen
                self.xcamera = XCamera()
                self.xcamera.on_picture_taken = self.picture_taken
                self.xcamera._camera.bind(on_load=self.camera_loaded)
                self.xcamera.play = True
                self.xcamera.index = 0
                self.layout.add_widget(self.xcamera)
                '''
                '''
                # Try: Reconnect camera - image freezes
                self.platform_camera.init_camera()
                self.platform_camera.start()
                '''
                self.platform_camera_paused = False
        
    def camera_loaded(self,platform_camera):
        # Depending on the platform, 'platform_camera' is in one of:
        # https://github.com/kivy/kivy/tree/master/kivy/core/camera
        if platform == 'android':
            # Save the CameraAndroid instance for on_pause/on_resume
            # Because well behaved apps disconnect and connect the camera
            # Assumes only one camera visible at one time.
            self.platform_camera = platform_camera
            # The goal is for the horizon in the image on the screen to
            # be parallel to the horizon in the physical world, and
            # mostly fill the screen.
            # So force long edge of the image to be parallel to long edge
            # of the screen. Thus the image is independent of the
            # orientation of the screen in the physical world.
            # The goal is met on my Pixel 3 by force_landscape()
            # The goal may not be met on all other devices.
            #
            #In camera portrait mode, a little extra delay is needed !
            Clock.schedule_once(self.force_landscape,0)

            # We need to check we can write to the shared directory at
            # each potential use, because we do not own the shared directory
            # and permission can be revoked.
            self.xcamera.directory = None # app install directory
            if check_permission(Permission.WRITE_EXTERNAL_STORAGE):
                path = join(primary_external_storage_path(),'Pictures')
                if not isdir(path):
                    mkdir(path)
                path = join(path,'XCamera')
                if not isdir(path):
                    mkdir(path)
                self.xcamera.directory = path

    def force_landscape(self,dt):
        self.xcamera.force_landscape()
        
    def picture_taken(self, filename):
        print('Picture taken and saved to {}'.format(filename))

def main():
    CameraApp().run()


if __name__ == '__main__':
    main()

[will702]

can u do that on kivy camera ? i @RobertFlatt

[RobertFlatt]

You don't say what "that" is, but Xcamera is a wrapper around Kivy camera so whatever "that" is, probably.

A quick look at the code would have shown you this https://github.com/kivy-garden/xcamera/blob/develop/src/kivy_garden/xcamera/xcamera.py#L9

If you want to know what Kivy camera can do, look at the code https://github.com/kivy/kivy/blob/master/kivy/uix/camera.py#L36

[will702]

yes i already try to change the index when the app is running and I got a pyjnius error @RobertFlatt

[0000Blaze]

I did somewhat fix the ISSUE 1 in my own project . I just added a index: 1 into the xcamera.kv file in example from https://github.com/kivy-garden/xcamera/tree/develop/src/kivy_garden/xcamera and also added a index: 1 into my own custom style.kv file calling the xcamera widget

[RobertFlatt]

I gave up with Xcamera and wrote a new camera https://github.com/Android-for-Python/Camera4Kivy

[wanaxe]

I had a similar situation. My laptop has an integrated camera (which actually includes 2: a RGB camera plus a IR camera), and a Logitech C170 webcam. OK for index = 0. Crash if index = 1 (i.e., error can't open camera by index).

Googled serveral hours for a solution. Then I tried larger index values, and finally get all cameras working:

• index = 0: Integrated RGB camera
• index = 2: Integrated IR camera
• index = 4: Logitech C170 webcam

Yet I have no idea how those indices are assigned. So, the solution / workaround is to try different index values.