Python tkinter的视频播放器，当我暂停视频时，我无法重新播放

Question

我正在创建 GUI 来播放视频文件。问题是当我暂停视频时，播放按钮无法重新播放该视频，我必须再次选择视频文件。

注意：由于我想在同一个 tkinter 窗口中显示视频，所以我不使用 OpenCV imshow 命令。相反，我使用的是“window.after”方法。

以下是我的代码：

我尝试使用“self.pause”变量来控制暂停状态。当我单击暂停按钮时，此布尔变量变为 True。但是，当我再次单击“播放”按钮时，我找不到合适的位置使其变为 False。

from tkinter import *
from tkinter import messagebox
from tkinter import filedialog
import PIL.Image, PIL.ImageTk
import cv2


class videoGUI:

    def __init__(self, window, window_title):

        self.window = window
        self.window.title(window_title)

        top_frame = Frame(self.window)
        top_frame.pack(side=TOP, pady=5)

        bottom_frame = Frame(self.window)
        bottom_frame.pack(side=BOTTOM, pady=5)

        self.pause = False   # Parameter that controls pause button

        self.canvas = Canvas(top_frame)
        self.canvas.pack()

        # Select Button
        self.btn_select=Button(bottom_frame, text="Select video file", width=15, command=self.open_file)
        self.btn_select.grid(row=0, column=0)

        # Play Button
        self.btn_play=Button(bottom_frame, text="Play", width=15, command=self.play_video)
        self.btn_play.grid(row=0, column=1)

        # Pause Button
        self.btn_pause=Button(bottom_frame, text="Pause", width=15, command=self.pause_video)
        self.btn_pause.grid(row=0, column=2)

        self.delay = 15   # ms

        self.window.mainloop()


    def open_file(self):

        self.pause = False

        self.filename = filedialog.askopenfilename(title="Select file", filetypes=(("MP4 files", "*.mp4"),
                                                                                         ("WMV files", "*.wmv"), ("AVI files", "*.avi")))
        print(self.filename)

        # Open the video file
        self.cap = cv2.VideoCapture(self.filename)

        self.width = self.cap.get(cv2.CAP_PROP_FRAME_WIDTH)
        self.height = self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT)

        self.canvas.config(width = self.width, height = self.height)


    def get_frame(self):   # get only one frame

        try:

            if self.cap.isOpened():
                ret, frame = self.cap.read()
                return (ret, cv2.cvtColor(frame, cv2.COLOR_BGR2RGB))

        except:
            messagebox.showerror(title='Video file not found', message='Please select a video file.')


    def play_video(self):

        # Get a frame from the video source, and go to the next frame automatically
        ret, frame = self.get_frame()

        if ret:
            self.photo = PIL.ImageTk.PhotoImage(image = PIL.Image.fromarray(frame))
            self.canvas.create_image(0, 0, image = self.photo, anchor = NW)

        if not self.pause:
            self.window.after(self.delay, self.play_video)


    def pause_video(self):
        self.pause = True


    # Release the video source when the object is destroyed
    def __del__(self):
        if self.cap.isOpened():
            self.cap.release()

##### End Class #####


# Create a window and pass it to videoGUI Class
videoGUI(Tk(), "EnJapan")

如果我在“play_video”函数中编写以下代码：

self.pause = False

暂停按钮不起作用。因为“window.after”方法会自动调用“play_video”函数并使“self.pause”为False。因此，暂停按钮将不起作用。

Answer 1

我将为播放按钮回调创建另一种方法。像这样的：

def play_start(self):
    self.pause = False
    self.play_video()

但是，如果播放按钮已经在播放，我会确保您禁用它。否则，如果多次按下播放按钮，您可能会有多个 play_video 的“实例”。

---

另一种方法是将播放和暂停按钮组合在一起，以便切换self.pause 的值。这样你就可以只有一个按钮和一个回调函数了。

Answer 2

问题：暂停按钮将不起作用。

参考：

• Tkinter.Widget.after-method - after(delay_ms, callback=None, *args)

  注册一个在给定时间后调用的回调。

• Tkinter.Widget.after_cancel-method - after_cancel(id)

  取消回调。

---

到cancel 已经为events 排队的self.play_video 更改以下内容：

def play_video(self):
    ...

    if self.pause:
        self.window.after_cancel(self.after_id)
    else:
        self.after_id = self.window.after(self.delay, self.play_video)

Answer 3

只需在 play_video(self) 方法中添加：

if self.pause == True:
    self.pause = False
    return
 

Answer 4

from tkinter import *
from tkinter import messagebox
from tkinter import filedialog
import PIL.Image, PIL.ImageTk
import cv2


class videoGUI:

    def __init__(self, window, window_title):

        self.window = window
        self.window.title(window_title)

        top_frame = Frame(self.window)
        top_frame.pack(side=TOP, pady=5)

        bottom_frame = Frame(self.window)
        bottom_frame.pack(side=BOTTOM, pady=5)

        self.pause = False   # Parameter that controls pause button

        self.canvas = Canvas(top_frame)
        self.canvas.pack()

        # Select Button
        self.btn_select=Button(bottom_frame, text="Select video file", width=15, command=self.open_file)
        self.btn_select.grid(row=0, column=0)

        # Play Button
        self.btn_play=Button(bottom_frame, text="Play", width=15, command=self.play_video)
        self.btn_play.grid(row=0, column=1)

        # Pause Button
        self.btn_pause=Button(bottom_frame, text="Pause", width=15, command=self.pause_video)
        self.btn_pause.grid(row=0, column=2)

        # Resume Button
        self.btn_resume=Button(bottom_frame, text="resume", width=15, command=self.resume_video)
        self.btn_resume.grid(row=0, column=3)

        self.delay = 15   # ms

        self.window.mainloop()


    def open_file(self):

        self.pause = False

        self.filename = filedialog.askopenfilename(title="Select file", filetypes=(("MP4 files", "*.mp4"),
                                                                                         ("WMV files", "*.wmv"), ("AVI files", "*.avi")))
        print(self.filename)

        # Open the video file
        self.cap = cv2.VideoCapture(self.filename)

        self.width = self.cap.get(cv2.CAP_PROP_FRAME_WIDTH)
        self.height = self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT)

        self.canvas.config(width = self.width, height = self.height)


    def get_frame(self):   # get only one frame

        try:

            if self.cap.isOpened():
                ret, frame = self.cap.read()
                return (ret, cv2.cvtColor(frame, cv2.COLOR_BGR2RGB))

        except:
            messagebox.showerror(title='Video file not found', message='Please select a video file.')


    def play_video(self):

        # Get a frame from the video source, and go to the next frame automatically
        ret, frame = self.get_frame()

        if ret:
            self.photo = PIL.ImageTk.PhotoImage(image = PIL.Image.fromarray(frame))
            self.canvas.create_image(0, 0, image = self.photo, anchor = NW)

        if not self.pause:
            self.window.after(self.delay, self.play_video)


    def pause_video(self):
        self.pause = True

#Addition
    def resume_video(self):
        self.pause=False
        self.play_video()


    # Release the video source when the object is destroyed
    def __del__(self):
        if self.cap.isOpened():
            self.cap.release()

##### End Class #####


# Create a window and pass it to videoGUI Class
videoGUI(Tk(), "EnJapan")

Answer 5

if not self.pause:
    self.window.after(self.delay, self.play_video)
 else:
    self.pause = False