[Python] Run a Quart web server in Python with Chaquopy on Android (Kotlin)

I am trying to make an Android app with a Quart app running on Python with Chaquopy but as soon as i add a call to Kotlin from Python i get Error starting Python server: Can't create handler inside thread Thread[Thread-4,5,main] that has not called Looper.prepare() from MainActivity. So i added a call to Looper but that gives me Error starting Python server: Method addObserver must be called on the main thread even though the call to run the Quart app is in the thread where the Python interpreter is started.

Kotlin:

package com.example.chatterbot

import android.annotation.SuppressLint
import android.net.http.SslError
import android.os.Bundle
import android.os.Looper
import android.util.Log
import android.webkit.SslErrorHandler
import android.webkit.WebView
import android.webkit.WebViewClient
import androidx.appcompat.app.AppCompatActivity
import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
import com.chaquo.python.Python
import com.chaquo.python.android.AndroidPlatform

class MainActivity : AppCompatActivity() {

private val tag: String = "MainActivity" // Define a tag for your logs
private var serverPort: Int? = null
private lateinit var webView: WebView
private lateinit var swipeRefreshLayout: SwipeRefreshLayout

@SuppressLint("SetJavaScriptEnabled")
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)

// Run the Python server in a background thread
Thread {
Looper.prepare()
Log.i(tag, "Starting server")
Log.i(tag, "IS STARTED")
Log.i(tag, Python.isStarted().toString())
if (! Python.isStarted()) {
Python.start(AndroidPlatform(this))
}
try {
val py = Python.getInstance()
py.getModule("app").callAttr("run")
} catch (e: Exception) {
Log.e(tag, "Error starting Python server: ${e.message}")
}
Looper.loop()
}.start()

// Set webview
Log.i(tag, "Starting webview")
webView = findViewById(R.id.webview)
webView.webViewClient = object : WebViewClient() {
override fun onReceivedSslError(
view: WebView?,
handler: SslErrorHandler?,
error: SslError?
) {
// Ignore SSL certificate errors (not recommended for production)
handler?.proceed()
}
}
webView.settings.javaScriptEnabled = true
webView.loadUrl("file:///android_asset/iframe/iframe.html")
swipeRefreshLayout = findViewById(R.id.swipe_refresh_layout)
swipeRefreshLayout.setOnRefreshListener {
webView.reload() // Reload the current page
swipeRefreshLayout.isRefreshing = false // Stop the refreshing animation
}
}

fun closeLoader() {
Log.i(tag, "Close loader")
webView.evaluateJavascript("closeLoader();", null)
}

}


Python:

from hypercorn.asyncio import serve
from hypercorn.config import Config
from quart import Quart, render_template
from com.example.chatterbot import MainActivity

activity = MainActivity()

app = Quart(__name__)

config = Config()
config.bind = [f"0.0.0.0:8000"]
config.debug = True

@app.route('/')
async def index():
return await render_template('index.html')

@app.after_serving
async def after_startup():
# This code will run after the server is fully loaded and ready to receive requests
print("Server ready")
activity.closeLoader() # <-- **The problem comes when i add this**

def run():
app.run(host="0.0.0.0", port=8000, debug=True)

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