streamlit_ros.py webgui

streamlit_ros.py

#!/usr/bin/env python3

import streamlit as st
import rospy
import time
import threading
from std_msgs.msg import String, Int32
from sensor_msgs.msg import Image
from cv_bridge import CvBridge

bridge = CvBridge() 

textROS_output  = None
imageROS_output = None

def callback_text(msg):
    global textROS_output
    textROS_output = msg.data

def callback_image(msg):
    global imageROS_output
    imageROS_output = bridge.imgmsg_to_cv2(msg, desired_encoding='passthrough') # "passthrough": destination image encoding will be the same as the image message encoding	

def getData():
    return textROS_output, imageROS_output

threading.Thread(target=lambda: rospy.init_node('streamlit_webgui_node', disable_signals=True)).start()
rospy.Subscriber("/textROS", String , callback_text)
rospy.Subscriber("/imageROS", Image , callback_image)

def main():
    selected_box = st.sidebar.selectbox('Choose one of the following', ('Welcome','demo-1'))
    if selected_box == 'Welcome':
        welcome() 
    if selected_box == 'demo-1':
        demo1()

def welcome():
    st.title('Webgui using Streamlit')
    
    st.subheader('A simple app that shows .... You can choose the options'
                  + ' from the left. I have implemented only a few to show how it works on Streamlit. ')
    
    st.image('overview.jpg', use_column_width=True)

def demo1():
    st.subheader('demo1')
    st.text('Demo1 text(s):')
    textLocation = st.empty()
    imageLocation = st.empty()

    while True:
        textROS, imageROS = getData()
        
        with textLocation:
            st.text(textROS)
        
        with imageLocation:
            if imageROS is not None:
                st.image(imageROS, caption='Result -->> Image')

        time.sleep(0.01)

if __name__ == '__main__':
    main()