Understanding the GUI constructor

The BaseLayout constructor accepts an ID (-1), a title string ('Fun with Filters'), a video capture object, and an optional argument that specifies the number of frames per second. Then, the first thing to do in the constructor is to try to read a frame from the captured object in order to determine the image size:

    def __init__(self,
                 capture: cv2.VideoCapture,
                 title: str = None,
                 parent=None,
                 window_id: int = -1,  # default value
                 fps: int = 10):
        self.capture = capture
        _, frame = self._acquire_frame()
        self.imgHeight, self.imgWidth = frame.shape[:2]

We will use the image size to prepare a buffer that will store each video frame as a bitmap and to set the size of the GUI. Because we want to display a bunch of control buttons below the current video frame, we set the height of the GUI to self.imgHeight + 20:

        super().__init__(parent, window_id, title,
                         size=(self.imgWidth, self.imgHeight + 20))
        self.fps = fps
        self.bmp = wx.Bitmap.FromBuffer(self.imgWidth, self.imgHeight, frame)

In the next section, we will build a basic layout for our application with a video stream and some buttons using wxPython.