A lightweight envrionment-agnostic SDK for constructing graphical user interfaces.
A typical Lens app is composed of two phases, there's the backend which is written in python and the frontend which is composed of HTML5/CSS3/JS similar to web development.
A bridge exists between the Python and WebKit components that can be traversed through signal/slot calls. For example Python slots can be reached via WebKit signals and conversely Webkit slots can be reached via Python signals.
A simple app is shown below.
import platform
from lens.app import App
app = App()
# bind to the 'close' signal
@app.bind('close')
def _close_app_cb(*args):
app.close()
# bind to the 'get-hostname' signal
@app.bind('get-hostname')
def _get_hostname_cb(*args):
app.emit('update-hostname', platform.node())
# start the app event loop
app.start("""
<!DOCTYPE html>
<html lang="en">
<head>
<link href="lens://css/lens.css" rel="stylesheet">
</head>
<body>
<h1>Lens. Demo</h1>
<p>This sample demonstrates simple communication between the Python and JS code paths.</p>
<p>Hostname: <span id="hostname"></span></p>
<button id="closeBtn">CLOSE</button>
<script src="lens://js/lens.js"></script>
<script>
document.addEventListener("DOMContentLoaded", function(event) {
document.getElementById("closeBtn").onclick = function() {
lens.emit('close');
};
lens.on('update-hostname', function(e, hostname) {
document.getElementById('hostname').innerHTML = hostname;
});
lens.emit('get-hostname');
});
</script>
</body>
</html>
""")During the development process it's possible to expose internal Lens debugging
by using the LENS_DEBUG environment variable. Setting the variable to 1 will
enable verbose Lens debugging messages.
LENS_DEBUG=1 ./app
On the WebKit side it's possible to get full Inspector ability by using the
LENS_INSPECTOR environment variable. Setting the variable to 1 will enable
right-click and opening of the Inspector.
LENS_INSPECTOR=1 ./app
When using QtWebEngine as the toolkit, setting LENS_INSPECTOR=1 will start the
remote debugging console on port 8001. The console is accessible using a
chromium based browser. The port can be changed by setting QTWEBENGINE_REMOTE_DEBUGGING
to the desired port.