Camera using pygst with custom source

custom_camera.py

"""
UNTESTED !!

camera_options is a dictionnary that is passed to Camera core class directly
so we can use it to pass custom option, such as video_src for pygst (if it's selected)

    camera = CustomCamera(camera_options={
        "video_src": "udpsrc port=5000 ! application/x-rtp, encoding-name=JPEG,payload=26 ! rtpjpegdepay ! jpegdec"})
"""

from kivy.uix.image import Image
from kivy.core.camera import Camera as CoreCamera
from kivy.properties import NumericProperty, ListProperty, \
    BooleanProperty


class CustomCamera(Image):
    play = BooleanProperty(True)
    index = NumericProperty(-1)
    resolution = ListProperty([-1, -1])
    camera_options = DictProperty({})

    def __init__(self, **kwargs):
        self._camera = None
        super(CustomCamera, self).__init__(**kwargs)
        if self.index == -1:
            self.index = 0
        on_index = self._on_index
        fbind = self.fbind
        fbind('index', on_index)
        fbind('resolution', on_index)
        on_index()

    def on_tex(self, *l):
        self.canvas.ask_update()

    def _on_index(self, *largs):
        self._camera = None
        if self.index < 0:
            return
        if self.resolution[0] < 0 or self.resolution[1] < 0:
            return
        self._camera = CoreCamera(index=self.index,
                                  resolution=self.resolution, stopped=True, **self.camera_options)
        self._camera.bind(on_load=self._camera_loaded)
        if self.play:
            self._camera.start()
            self._camera.bind(on_texture=self.on_tex)

    def _camera_loaded(self, *largs):
        self.texture = self._camera.texture
        self.texture_size = list(self.texture.size)

    def on_play(self, instance, value):
        if not self._camera:
            return
        if value:
            self._camera.start()
        else:
            self._camera.stop()