cefpython/examples/tutorial.py at cefpython56 · lineCode/cefpython · GitHub

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# Tutorial example. Doesn't depend on any third party GUI framework.

# Tested with CEF Python v56.2+

from cefpython3 import cefpython as cef

import base64

import platform

import sys

import threading

# HTML code. Browser will navigate to a Data uri created

# from this html code.

HTML_code = """

<!DOCTYPE html>

<html>

<head>

body,html { font-family: Arial; font-size: 11pt; }

div.msg { margin: 0.2em; line-height: 1.4em; }

b { background: #ccc; font-weight: bold; font-size: 10pt;

padding: 0.1em 0.2em; }

b.Python { background: #eee; }

i { font-family: Courier new; font-size: 10pt; border: #eee 1px solid;

padding: 0.1em 0.2em; }

</style>

function js_print(lang, event, msg) {

msg = "<b class="+lang+">"+lang+": "+event+":</b> " + msg;

console = document.getElementById("console")

console.innerHTML += "<div class=msg>"+msg+"</div>";

}

function js_callback_1(ret) {

js_print("Javascript", "html_to_data_uri", ret);

}

function js_callback_2(msg, py_callback) {

js_print("Javascript", "js_callback", msg);

py_callback("String sent from Javascript");

}

window.onload = function(){

js_print("Javascript", "window.onload", "Called");

js_print("Javascript", "python_property", python_property);

html_to_data_uri("test", js_callback_1);

external.test_multiple_callbacks(js_callback_2);

};

</script>

</head>

<body>

<h1>Tutorial example</h1>

</body>

</html>

"""

def main():

check_versions()

sys.excepthook = cef.ExceptHook # To shutdown all CEF processes on error

cef.Initialize()

set_global_handler()

browser = cef.CreateBrowserSync(url=html_to_data_uri(HTML_code),

window_title="Tutorial")

set_client_handlers(browser)

set_javascript_bindings(browser)

cef.MessageLoop()

cef.Shutdown()

def check_versions():

print("[tutorial.py] CEF Python {ver}".format(ver=cef.__version__))

print("[tutorial.py] Python {ver} {arch}".format(

ver=platform.python_version(), arch=platform.architecture()[0]))

assert cef.__version__ >= "56.2", "CEF Python v56.2+ required to run this"

def html_to_data_uri(html, js_callback=None):

# This function is called in two ways:

# 1. From Python: in this case value is returned

# 2. From Javascript: in this case value cannot be returned because

# inter-process messaging is asynchronous, so must return value

# by calling js_callback.

html = html.encode("utf-8", "replace")

b64 = base64.b64encode(html).decode("utf-8", "replace")

ret = "data:text/html;base64,{data}".format(data=b64)

if js_callback:

js_print(js_callback.GetFrame().GetBrowser(),

"Python", "html_to_data_uri",

"Called from Javascript. Will call Javascript callback now.")

js_callback.Call(ret)

else:

return ret

def set_global_handler():

# A global handler is a special handler for callbacks that

# must be set before Browser is created using

# SetGlobalClientCallback() method.

global_handler = GlobalHandler()

cef.SetGlobalClientCallback("OnAfterCreated",

global_handler.OnAfterCreated)

def set_client_handlers(browser):

client_handlers = [LoadHandler(), DisplayHandler()]

for handler in client_handlers:

browser.SetClientHandler(handler)

def set_javascript_bindings(browser):

external = External(browser)

bindings = cef.JavascriptBindings(

bindToFrames=False, bindToPopups=False)

bindings.SetProperty("python_property", "This property was set in Python")

bindings.SetFunction("html_to_data_uri", html_to_data_uri)

bindings.SetObject("external", external)

browser.SetJavascriptBindings(bindings)

def js_print(browser, lang, event, msg):

# Execute Javascript function "js_print"

browser.ExecuteFunction("js_print", lang, event, msg)

class GlobalHandler(object):

def OnAfterCreated(self, browser, **_):

# DOM is not yet loaded. Using js_print at this moment will

# throw an error: "Uncaught ReferenceError: js_print is not defined".

# We make this error on purpose. This error will be intercepted

# in DisplayHandler.OnConsoleMessage.

js_print(browser, "Python", "OnAfterCreated",

"This will probably never display as DOM is not yet loaded")

# Delay print by 0.5 sec, because js_print is not available yet

args = [browser, "Python", "OnAfterCreated",

"(Delayed) Browser id="+str(browser.GetIdentifier())]

threading.Timer(0.5, js_print, args).start()

class LoadHandler(object):

def OnLoadingStateChange(self, browser, is_loading, **_):

# This callback is called twice, once when loading starts

# (is_loading=True) and second time when loading ends

# (is_loading=False).

if not is_loading:

# Loading is complete. DOM is ready.

js_print(browser, "Python", "OnLoadingStateChange",

"Loading is complete")

class DisplayHandler(object):

def OnConsoleMessage(self, browser, message, **_):

# This will intercept js errors, see comments in OnAfterCreated

if "error" in message.lower() or "uncaught" in message.lower():

# Prevent infinite recurrence in case something went wrong

if "js_print is not defined" in message.lower():

if hasattr(self, "js_print_is_not_defined"):

print("Python: OnConsoleMessage: "

"Intercepted Javascript error: "+message)

return

else:

self.js_print_is_not_defined = True

# Delay print by 0.5 sec, because js_print may not be

# available yet due to DOM not ready.

args = [browser, "Python", "OnConsoleMessage",

"(Delayed) Intercepted Javascript error: <i>{error}</i>"

.format(error=message)]

threading.Timer(0.5, js_print, args).start()

class External(object):

def __init__(self, browser):

self.browser = browser

def test_multiple_callbacks(self, js_callback):

"""Test both javascript and python callbacks."""

js_print(self.browser, "Python", "test_multiple_callbacks",

"Called from Javascript. Will call Javascript callback now.")

def py_callback(msg_from_js):

js_print(self.browser, "Python", "py_callback", msg_from_js)

js_callback.Call("String sent from Python", py_callback)

if __name__ == '__main__':

main()

cefpython/examples/tutorial.py at cefpython56 · lineCode/cefpython · GitHub

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