How to control a frame from another frame?

ghz 2days ago ⋅ 4 views

I'm writing a small app which has 2 separate frames.

The first frame is like a video player controller. It has Play/Stop/Pause buttons etc. It's named controller.py.

The second frame contains OpenGL rendering and many things inside it, but everything is wrapped inside a Frame() class as the above. It's named model.py.

I'm up to the final part where I have to "join" these two together. Does anyone know how to control a frame (model.py) from another frame (controller.py)?

I would like to do something like a movie player when you clicks play it pops up a new window and play until the stop button is clicked.

If you know how, please let me know. (Just tell me in general no need to specific).

Answer

To control one frame (model.py) from another (controller.py) in a typical GUI application, you need to set up communication between the two frames. This is usually done using event handling, signals, or by sharing a reference to one frame inside the other. Below are the general steps on how to achieve this:

1. Create the Two Frames as Separate Classes:

Each frame (i.e., controller.py and model.py) should be defined as a separate class. In the context of GUI frameworks (like tkinter, PyQt, or wxPython), you can define the frames as Tk windows, QWidget objects, or Panel objects respectively.

  • controller.py: Manages the video controls (Play, Pause, Stop buttons).
  • model.py: Manages the OpenGL rendering and displays the video.

2. Set Up Event Handling for Interaction:

Use event handlers to link the actions on the controller.py (e.g., Play button press) to functions/methods in model.py.

Here are some general strategies depending on the GUI framework you're using:

If using tkinter:

In tkinter, you would typically pass a reference of model.py's frame to controller.py to allow interaction. Here's how you can achieve that:

controller.py (Frame with buttons):

import tkinter as tk
from model import VideoPlayer

class ControllerFrame(tk.Frame):
    def __init__(self, master, video_player):
        super().__init__(master)
        self.video_player = video_player  # Reference to the model
        self.pack()
        
        self.play_button = tk.Button(self, text="Play", command=self.play_video)
        self.play_button.pack()

        self.stop_button = tk.Button(self, text="Stop", command=self.stop_video)
        self.stop_button.pack()

    def play_video(self):
        self.video_player.play()  # Call the play method of model.py

    def stop_video(self):
        self.video_player.stop()  # Call the stop method of model.py

if __name__ == "__main__":
    root = tk.Tk()
    video_player = VideoPlayer(root)  # Create an instance of model.py
    controller_frame = ControllerFrame(root, video_player)
    controller_frame.pack()
    root.mainloop()

model.py (Frame with OpenGL rendering):

import tkinter as tk

class VideoPlayer(tk.Frame):
    def __init__(self, master):
        super().__init__(master)
        self.master = master
        self.is_playing = False  # State variable to track play/pause
        self.pack()
        self.video_canvas = tk.Canvas(self, width=640, height=480)
        self.video_canvas.pack()

    def play(self):
        if not self.is_playing:
            self.is_playing = True
            print("Video playing")
            # Initialize video playback and OpenGL rendering
            # (Add OpenGL rendering logic here)
    
    def stop(self):
        if self.is_playing:
            self.is_playing = False
            print("Video stopped")
            # Stop video playback and OpenGL rendering cleanup
            # (Stop OpenGL rendering logic here)
    
    def pause(self):
        if self.is_playing:
            self.is_playing = False
            print("Video paused")
            # Pause the video playback logic

if __name__ == "__main__":
    root = tk.Tk()
    player = VideoPlayer(root)
    player.pack()
    root.mainloop()

Key Concepts:

  • Communication between frames: The ControllerFrame has a reference to VideoPlayer (the model). When the "Play" button is clicked, it calls the play() method on VideoPlayer, which handles the OpenGL rendering and video playback.

  • Passing references: In the example above, ControllerFrame is given a reference to the VideoPlayer class by passing it as an argument to the ControllerFrame constructor. This allows ControllerFrame to call methods (like play(), stop(), etc.) on the VideoPlayer instance.

  • Threading/Asynchronous tasks: If your OpenGL rendering or video playback is heavy, you might want to use threading or asynchronous tasks to avoid blocking the GUI. For instance, model.py could use a separate thread to handle video playback while keeping the UI responsive.

3. Handling Event-Driven Communication:

In GUI programming, the interaction between the controller (buttons) and the model (video display/OpenGL) can be event-driven:

  • Button clicks trigger methods in the model.py frame.
  • You can add additional buttons for Pause, Seek, Volume, etc., by adding more methods in controller.py and corresponding methods in model.py.

If using PyQt:

The process in PyQt is similar but uses signals and slots. The video player frame (model.py) would emit signals to communicate with the controller frame (controller.py), which listens to those signals.

controller.py (Frame with buttons):

from PyQt5.QtWidgets import QWidget, QPushButton, QVBoxLayout
from model import VideoPlayer

class ControllerFrame(QWidget):
    def __init__(self, video_player):
        super().__init__()
        self.video_player = video_player  # Reference to the model

        # UI Elements
        self.play_button = QPushButton('Play', self)
        self.stop_button = QPushButton('Stop', self)

        self.play_button.clicked.connect(self.play_video)
        self.stop_button.clicked.connect(self.stop_video)

        layout = QVBoxLayout(self)
        layout.addWidget(self.play_button)
        layout.addWidget(self.stop_button)
        self.setLayout(layout)

    def play_video(self):
        self.video_player.play()  # Call play method in model

    def stop_video(self):
        self.video_player.stop()  # Call stop method in model

model.py (Frame with OpenGL rendering):

from PyQt5.QtWidgets import QWidget
from PyQt5.QtCore import pyqtSignal

class VideoPlayer(QWidget):
    play_signal = pyqtSignal()
    stop_signal = pyqtSignal()

    def __init__(self):
        super().__init__()
        self.is_playing = False

    def play(self):
        if not self.is_playing:
            self.is_playing = True
            print("Video playing")
            # Handle OpenGL rendering and video playback

    def stop(self):
        if self.is_playing:
            self.is_playing = False
            print("Video stopped")
            # Handle OpenGL cleanup and stop video playback

In this case, you can use signals and slots in PyQt to bind buttons to specific methods of the video player frame.

Final Considerations:

  • Threading/Async Tasks: If the OpenGL rendering or video playback is computationally intensive, consider using Python's threading or asyncio to ensure the GUI remains responsive while the video is playing.

  • Separation of Concerns: Make sure to maintain the separation of concerns by keeping video-related logic in model.py and UI/interaction logic in controller.py.

Let me know if you need more details or examples!

#py