How to use Timer

[dhunjoshi]

I Want to increment value of a text in time interval. How can i use timer?

[FeodorFitsner]

Sure, there is an example at the second part of this article: https://flet.dev/docs/guides/python/user-controls

[dhunjoshi]

Thanks for your quick response. I was using timer for showing webcam image. But its flicker on every frame , is it because of page update? any example for webcam?

[dhunjoshi]

import flet as ft
import time, threading
import cv2
import base64
from io import BytesIO
from PIL import Image

class Countdown(ft.UserControl):

def __init__(self, seconds):
    super().__init__()
    self.vid = cv2.VideoCapture(0)
    self.counter = ft.Text(value="0000",expand=1,
                    text_align="center",height=30,)
    
    self.image = ft.Image(src_base64=self.get_base_64_image())

    self.c = ft.Container(
        expand=1,
        height=40,
        bgcolor=ft.colors.AMBER,
        border_radius=5,
        padding=10,
        content=self.counter,            

    )
    
    self.reset_btn  = ft.ElevatedButton(text="Reset", width=120,
    on_click=self.reset_timer)
    self.stop_btn  = ft.ElevatedButton(text="Stop", width=120, on_click=self.stop_timer)
    self.stop = False

    self.seconds = seconds

def get_base_64_image(self):
    ret, frame = self.vid.read()
    if ret==False:
        frame = cv2.imread('assets/images/logo.jpeg')
    _, im_arr = cv2.imencode('.jpg', frame)  # im_arr: image in Numpy one-dim array format.
    im_bytes = im_arr.tobytes()
    im_b64 = base64.b64encode(im_bytes)
    im_b64_str = (str(im_b64).replace("b'","").replace("'",""))
    return im_b64_str

def reset_timer(self, e):
    print("Reset")
    
    if self.stop :
        self.reset_btn.disabled=True
        self.stop=False
        self.seconds=1200
        self.update_timer()

def stop_timer(self, e):
    print("Stop")
    self.stop=True
    self.reset_btn.disabled = not self.stop
    self.update()


def did_mount(self):
    self.running = True
    self.th = threading.Thread(target=self.update_timer, args=(), daemon=True)
    self.th.start()
    print("did_mount")

def will_unmount(self):
    self.running = False
    print("Unmount")

def update_timer(self):
    while not self.stop:
        mins, secs = divmod(self.seconds, 60)
        self.counter.value = "{:04d}:{:02d}".format(mins, secs)            
        time.sleep(0.001)
        self.seconds -= 1
        self.image.src_base64=self.get_base_64_image()
        self.update()

def build(self):
    self.reset_btn.disabled=True
    self.countdown = ft.Column(
        controls=[
            ft.Row(
                    controls=[
                        self.c,
                        self.reset_btn,
                        self.stop_btn,
                    ],
                ),
              self.image,   
            ],
        )   
    
   
    return self.countdown

def main(page: ft.Page):
c1 = Countdown(1200)

page.add(c1)

ft.app(target=main,
assets_dir="assets")

[FeodorFitsner]

Set gapless_playback=True to avoid flickering: https://flet.dev/docs/controls/image#gapless_playback