Inline WebView Within Your kivy App

When Developing an application, you might often need the user to visit
a webview temporary and then return to your application.
With python, you can simply use the 'webrowser' module to open up an external browser on android

Example:

	import webrowser
	browser = webrowser.get('android') # get the android registered browser by python for android (P4A)
	browser.open('http://ordereat.co')

view raw description.py hosted with ❤ by GitHub

This will open up an external browser, else if there are multiple browser installed,
it will open a chooser for the user to select one.
But most times, for a better user experience we might not want the user to leave
our application and still access the web.
Then we might want to make use of an Embedded WebView

But wait a minute you might be wondering that your have seen something like this
before and how to use it on android on kivy wiki

	import kivy
	from kivy.app import App
	from kivy.lang import Builder
	from kivy.utils import platform
	from kivy.uix.widget import Widget
	from kivy.clock import Clock
	from jnius import autoclass
	from android.runnable import run_on_ui_thread
	WebView = autoclass('android.webkit.WebView')
	WebViewClient = autoclass('android.webkit.WebViewClient')
	activity = autoclass('org.kivy.android.PythonActivity').mActivity
	class Wv(Widget):
	def __init__(self, **kwargs):
	super(Wv, self).__init__(**kwargs)
	Clock.schedule_once(self.create_webview, 0)
	@run_on_ui_thread
	def create_webview(self, *args):
	webview = WebView(activity)
	webview.getSettings().setJavaScriptEnabled(True)
	wvc = WebViewClient();
	webview.setWebViewClient(wvc);
	activity.setContentView(webview)
	webview.loadUrl('http://www.google.com')
	class ServiceApp(App):
	def build(self):
	return Wv()
	if __name__ == '__main__':
	ServiceApp().run()

view raw embeded_webview.py hosted with ❤ by GitHub

But it doesn't work,
Why, taking a look at the code
what it basically does is
1). It create a webview
2). Sets a webview client for the webview
3). And loads the webview


Ok everything above works well, but the problem arises when you want to go back
to the main application. usually you would want to watch for the on_key_down button
from the window to detect when the back button is pressed so you can go back within
the webview and then when you can't go back anymore you close the webview

But when calling setContentView() on the webview android looses our
view and puts the app on pause which also put the python interpreter on pause
which means you won't recieve any callbacks

even when the code above is written in java and you get a back button callback
setting setContentView() and removeView() isn't stable and might crash your application

so what do we do
Instead of of using setContentView(), we get our activity main layout

	layout = activity.getLayout()
	layout.addView(webview)

view raw fjf.py hosted with ❤ by GitHub

with this our application won't pause and we get our normal callbacks.
to remove the webview you just simple say

	layout = activity.getLayout()
	layout.removeView(webview)

view raw kdkd.py hosted with ❤ by GitHub

# link to file
The whole code is in this file below ( android_inline.py ),

	from kivy.core.window import Window
	from kivy import platform
	from kivy.clock import Clock
	from jnius import autoclass
	from android.runnable import run_on_ui_thread
	WebView = autoclass('android.webkit.WebView')
	WebViewClient = autoclass('android.webkit.WebViewClient')
	ViewGroup = autoclass('android.view.ViewGroup')
	LayoutParams = autoclass('android.view.ViewGroup$LayoutParams')
	activity = autoclass('org.kivy.android.PythonActivity').mActivity
	class AndroidWebView(object):
	def open(self, url, new=0, autoraise=True):
	return start_webview(url)
	def open_new(self, url):
	return start_webview(url)
	def open_new_tab(self, url):
	return start_webview(url)
	def start_webview(self, url):
	Window.bind(on_key_down=self.listen_for_key)
	Clock.schedule_once( lambda *args: self.create_webview(url), 0)
	return True
	@run_on_ui_thread
	def create_webview(self, url):
	''' attaching webview to app '''
	self.webview = WebView(activity)
	settings = self.webview.getSettings()
	settings.setJavaScriptEnabled(True) # enables js
	settings.setDomStorageEnabled(True)
	settings.setUseWideViewPort(True) # enables viewport html meta tags
	settings.setLoadWithOverviewMode(True) # uses viewport
	settings.setSupportZoom(True) # enables zoom
	self.webview.loadUrl(url)
	self.wvc = WebViewClient()
	self.webview.setWebViewClient(self.wvc)
	self.webview.setLayoutParams(LayoutParams(
	LayoutParams.FILL_PARENT,
	LayoutParams.FILL_PARENT))
	activity.getLayout().addView(self.webview)
	def listen_for_key(self, keyboard, keycode, text, *modifiers):
	if keycode == 27:
	self.on_back_button()
	return True
	@run_on_ui_thread
	def on_back_button(self, *args):
	if self.webview:
	if self.webview.canGoBack():
	self.webview.goBack() # webview going back inline
	else:
	self.detach_webview()
	def detach_webview(self, *args):
	# detaching webview from view port
	Window.unbind(on_key_down=self.listen_for_key)
	if self.webview:
	self.webview.clearHistory()
	self.webview.clearCache(True)
	self.webview.loadUrl("about:blank")
	self.webview.freeMemory() # probably not needed anymore
	if not self.webview.getParent() is None
	activity.getLayout().removeView(self.webview)
	self.webview = None
	self.wvc = None
	import webbrowser
	webbrowser.register('android_inline', AndroidWebView)
	if __name__ == '__main__':
	from kivy.app import App
	from kivy.uix.button import Button
	class TestApp(App):
	def build(self):
	btn = Button(text='Open Web',
	on_release=self.open_web)
	root.add_widget(btn)
	def open_web(self):
	browser = webbrowser.get('android_inline')
	browser.open('https://ordereat.co')
	TestApp().run()

view raw android_inline.py hosted with ❤ by GitHub

so basically you can import the code and it will register the android inline browser
on the webbrowser,
so finally in your code you can just run

	import android_inline
	import webbrowser
	browser = webbrowser.get('android_inline')
	browser.open('http://ordereat.co')

view raw inline.py hosted with ❤ by GitHub