为什么捕获视频不会在 tkinter 循环中刷新? [英] why capture video does not refresh in tkinter loop?

问题描述

我期待视频捕获刷新屏幕.当它不是一堂课时，它按我的预期工作.然后我将它转换为 oop -below.它没有刷新......然后我预计之后"会完成这项工作.显然我不明白之后如何工作?它不是连续调用 - 在我的情况下 - root.vidImg.vid() .如果是，为什么 self.cap = cv2.VideoCapture(0) 不捕获并显示新图像?提前感谢您的帮助

I am expecting video capture refreshes the screen. When it was not a class it was working as I expected. Then I converted it to oop -below. It did not refresh... Then I expected "after" would do the work. Apperently I did not understand how after works? Does not it call -in my case below- root.vidImg.vid() continuously. If yes why self.cap = cv2.VideoCapture(0) does not captures and shows a new image? Thanks for the helps in advance

这是我的代码...

import tkinter as tk
from PIL import Image, ImageTk
import cv2



class Window(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)

        self.videoFrm = tk.Frame(self, width=480, bg='yellow', height=320)
        self.videoFrm.grid(row=0, column=0, sticky=tk.NW)
        self.vidImg = cnvs(self.videoFrm,self)
        self.vidImg.grid()

class cnvs(tk.Frame):
    def __init__(self,parent,controller):
        tk.Frame.__init__(self,parent)
        self.controller = controller

        self.canvas = tk.Canvas(self, width=480, height=320, bg='green')
        self.canvas.grid()

    def vid(self):
        # Capture video frames
        self.cap = cv2.VideoCapture(0)

        _, self.frame = self.cap.read()
        self.img = cv2.flip(self.frame, 1)

        self.cv2image = cv2.cvtColor(self.img, cv2.COLOR_BGR2RGBA)
        self.cv2image = cv2.resize(self.cv2image, (0, 0), fx=0.2, fy=0.2)
        self.img = Image.fromarray(self.cv2image)
        self.imgtk = ImageTk.PhotoImage(image=self.img)

        self.canvas.create_image(10, 10, anchor=tk.NW, image=self.imgtk)

def main():

    root = Window()
    root.after(0, root.vidImg.vid())
    root.mainloop()


if __name__ == '__main__':
    main()

推荐答案

使用 after 创建一个动画循环code>方法，需要让动画函数多次调用自身.

To create an animation loop with the after method, you need to let the animation function call itself multiple times.

在您的情况下，您可以将以下方法添加到 cnvs 类:

In your case, you could add the following method to the cnvs class:

def video_loop(self):
    self.vid()
    self.controller.after(10, self.video_loop)

然后在 mainloop() 之前调用它.

and then call it just before the mainloop().

此外，与其为每一帧向画布添加新图像，不如仅更改现有图像 使用 canvas.itemconfig(...).

Furthermore, instead of adding a new image to the canvas for each frame, it's probably better to just change the existing image using canvas.itemconfig(...).

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