# Usage

# Basics

The bare minimum to get pywebview up and running is

import webview

window = webview.create_window('Woah dude!', 'https://pywebview.flowrl.com')

The create_window function creates a new window and returns a Window object instance. Windows created before webview.start() are shown as soon as the GUI loop is started. Windows created after the GUI loop is started are shown immediately. You may create as many windows as you wish. All the opened windows are stored as a list in webview.windows. The windows are stored in a creation order.

import webview

first_window = webview.create_window('Woah dude!', 'https://pywebview.flowrl.com')
second_window = webview.create_window('Second window', 'https://woot.fi')

pywebview gives a choice of using several web renderers. To change a web renderer, set the gui parameter of the start function to the desired value (e.g cef or qt). See Renderer for details.

# Backend logic

webview.start starts a GUI loop and blocks further code from execution until last window is destroyed. With the GUI loop being blocking, you must execute your backend logic in a separate thread or a process. You can execute your backend code by passing your function to webview.start(func, (params,)). This will launch a separate thread and is identical to starting a thread by hand.

import webview

def custom_logic(window):
    window.evaluate_js('alert("Nice one brother")')

window = webview.create_window('Woah dude!', html='<h1>Woah dude!<h1>')
webview.start(custom_logic, window)
# anything below this line will be executed after program is finished executing

# Communication between Javascript and Python

You can both run Javascript code from Python and vice versa. To run Javascript from Python, use window.evaluate_js(code). The function returns result of the last line in the Javascript code. If code returns a promise, you can resolve it by passing a callback function window.evaluate_js(code, callback). If Javascript throws an error, window.evaluate_js raises a webview.errors.JavascriptException.

To run Python from Javascript, you need to expose your API class with webview.create_window(url, js_api=api_instance). Class member functions will be available in Javascript domain as window.pywebview.api.funcName. You may expose single functions with window.expose(func) also during the runtime. See interdomain communication for details.

import webview

class Api():
  def log(self, value):

webview.create_window("Test", html="<button onclick='pywebview.api.log(\"Woah dude!\")'>Click me</button>", js_api=Api())

Or alternatively you may use a more traditional approach with REST API paired with a WSGI server for interdomain communication. See Flask app (opens new window) for an example.

# HTTP server

pywebview uses internally bottle.py (opens new window) HTTP server for serving static files. Relative local paths are served with a built-in HTTP server. The entrypoint directory serves as a HTTP server root with everything under the directory and its directories shared. You may want to enable SSL for the server by setting webview.start(ssl=True).

import webview

webview.create_window('Woah dude!', 'src/index.html')

If you wish to use an external WSGI compatible HTTP server, you can pass a server application object as an URL.

from flask import Flask
import webview

server = Flask(__name__, static_folder='./assets', template_folder='./templates')
webview.create_window('Flask example', server)

If your intent is to serve files without an HTTP server using the file:// protocol, you can achieve this by either using an absolute file path or by prefixing the path with the file:// protocol.

import webview

# this will be served as file:///home/pywebview/project/index.html
webview.create_window('Woah dude!', '/home/pywebview/project/index.html')

# Loading HTML

Alternatively, you can load HTML by setting the html parameter or with window.load_html function. A limitation of this approach is that but file system does not exist in the context of the loaded page. Images and other assets can be loaded only inline using Base64.

import webview

webview.create_window('Woah dude!', html='<h1>Woah dude!<h1>')