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qwebchannel.js

Uploaded on Mar 18 2022 07:13 by jbpeter

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2016 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtWebChannel module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

"use strict";

var QWebChannelMessageTypes = {
signal: 1,
propertyUpdate: 2,
init: 3,
idle: 4,
debug: 5,
invokeMethod: 6,
connectToSignal: 7,
disconnectFromSignal: 8,
setProperty: 9,
response: 10,
};

var QWebChannel = function (transport, initCallback) {
if (typeof transport !== "object" || typeof transport.send !== "function") {
console.error("The QWebChannel expects a transport object with a send function and onmessage callback property." +
" Given is: transport: " + typeof (transport) + ", transport.send: " + typeof (transport.send));
return;
}

var channel = this;
this.transport = transport;

this.send = function (data) {
if (typeof (data) !== "string") {
data = JSON.stringify(data);
}
channel.transport.send(data);
}

this.transport.onmessage = function (message) {
var data = message.data;
if (typeof data === "string") {
data = JSON.parse(data);
}
switch (data.type) {
case QWebChannelMessageTypes.signal:
channel.handleSignal(data);
break;
case QWebChannelMessageTypes.response:
channel.handleResponse(data);
break;
case QWebChannelMessageTypes.propertyUpdate:
channel.handlePropertyUpdate(data);
break;
default:
console.error("invalid message received:", message.data);
break;
}
}

this.execCallbacks = {};
this.execId = 0;
this.exec = function (data, callback) {
if (!callback) {
// if no callback is given, send directly
channel.send(data);
return;
}
if (channel.execId === Number.MAX_VALUE) {
// wrap
channel.execId = Number.MIN_VALUE;
}
if (data.hasOwnProperty("id")) {
console.error("Cannot exec message with property id: " + JSON.stringify(data));
return;
}
data.id = channel.execId++;
channel.execCallbacks[data.id] = callback;
channel.send(data);
};

this.objects = {};

this.handleSignal = function (message) {
var object = channel.objects[message.object];
if (object) {
object.signalEmitted(message.signal, message.args);
} else {
console.warn("Unhandled signal: " + message.object + "::" + message.signal);
}
}

this.handleResponse = function (message) {
if (!message.hasOwnProperty("id")) {
console.error("Invalid response message received: ", JSON.stringify(message));
return;
}
channel.execCallbacks[message.id](message.data);
delete channel.execCallbacks[message.id];
}

this.handlePropertyUpdate = function (message) {
message.data.forEach(data => {
var object = channel.objects[data.object];
if (object) {
object.propertyUpdate(data.signals, data.properties);
} else {
console.warn("Unhandled property update: " + data.object + "::" + data.signal);
}
});
channel.exec({ type: QWebChannelMessageTypes.idle });
}

this.debug = function (message) {
channel.send({ type: QWebChannelMessageTypes.debug, data: message });
};

channel.exec({ type: QWebChannelMessageTypes.init }, function (data) {
for (const objectName of Object.keys(data)) {
new QObject(objectName, data[objectName], channel);
}

// now unwrap properties, which might reference other registered objects
for (const objectName of Object.keys(channel.objects)) {
channel.objects[objectName].unwrapProperties();
}

if (initCallback) {
initCallback(channel);
}
channel.exec({ type: QWebChannelMessageTypes.idle });
});
};

function QObject(name, data, webChannel) {
this.__id__ = name;
webChannel.objects[name] = this;

// List of callbacks that get invoked upon signal emission
this.__objectSignals__ = {};

// Cache of all properties, updated when a notify signal is emitted
this.__propertyCache__ = {};

var object = this;

// ----------------------------------------------------------------------

this.unwrapQObject = function (response) {
if (response instanceof Array) {
// support list of objects
return response.map(qobj => object.unwrapQObject(qobj))
}
if (!(response instanceof Object))
return response;

if (!response["__QObject*__"] || response.id === undefined) {
var jObj = {};
for (const propName of Object.keys(response)) {
jObj[propName] = object.unwrapQObject(response[propName]);
}
return jObj;
}

var objectId = response.id;
if (webChannel.objects[objectId])
return webChannel.objects[objectId];

if (!response.data) {
console.error("Cannot unwrap unknown QObject " + objectId + " without data.");
return;
}

var qObject = new QObject(objectId, response.data, webChannel);
qObject.destroyed.connect(function () {
if (webChannel.objects[objectId] === qObject) {
delete webChannel.objects[objectId];
// reset the now deleted QObject to an empty {} object
// just assigning {} though would not have the desired effect, but the
// below also ensures all external references will see the empty map
// NOTE: this detour is necessary to workaround QTBUG-40021
Object.keys(qObject).forEach(name => delete qObject[name]);
}
});
// here we are already initialized, and thus must directly unwrap the properties
qObject.unwrapProperties();
return qObject;
}

this.unwrapProperties = function () {
for (const propertyIdx of Object.keys(object.__propertyCache__)) {
object.__propertyCache__[propertyIdx] = object.unwrapQObject(object.__propertyCache__[propertyIdx]);
}
}

function addSignal(signalData, isPropertyNotifySignal) {
var signalName = signalData[0];
var signalIndex = signalData[1];
object[signalName] = {
connect: function (callback) {
if (typeof (callback) !== "function") {
console.error("Bad callback given to connect to signal " + signalName);
return;
}

object.__objectSignals__[signalIndex] = object.__objectSignals__[signalIndex] || [];
object.__objectSignals__[signalIndex].push(callback);

// only required for "pure" signals, handled separately for properties in propertyUpdate
if (isPropertyNotifySignal)
return;

// also note that we always get notified about the destroyed signal
if (signalName === "destroyed" || signalName === "destroyed()" || signalName === "destroyed(QObject*)")
return;

// and otherwise we only need to be connected only once
if (object.__objectSignals__[signalIndex].length == 1) {
webChannel.exec({
type: QWebChannelMessageTypes.connectToSignal,
object: object.__id__,
signal: signalIndex
});
}
},
disconnect: function (callback) {
if (typeof (callback) !== "function") {
console.error("Bad callback given to disconnect from signal " + signalName);
return;
}
// This makes a new list. This is important because it won't interfere with
// signal processing if a disconnection happens while emittig a signal
object.__objectSignals__[signalIndex] = (object.__objectSignals__[signalIndex] || []).filter(function (c) {
return c != callback;
});
if (!isPropertyNotifySignal && object.__objectSignals__[signalIndex].length === 0) {
// only required for "pure" signals, handled separately for properties in propertyUpdate
webChannel.exec({
type: QWebChannelMessageTypes.disconnectFromSignal,
object: object.__id__,
signal: signalIndex
});
}
}
};
}

/**
* Invokes all callbacks for the given signalname. Also works for property notify callbacks.
*/
function invokeSignalCallbacks(signalName, signalArgs) {
var connections = object.__objectSignals__[signalName];
if (connections) {
connections.forEach(function (callback) {
callback.apply(callback, signalArgs);
});
}
}

this.propertyUpdate = function (signals, propertyMap) {
// update property cache
for (const propertyIndex of Object.keys(propertyMap)) {
var propertyValue = propertyMap[propertyIndex];
object.__propertyCache__[propertyIndex] = this.unwrapQObject(propertyValue);
}

for (const signalName of Object.keys(signals)) {
// Invoke all callbacks, as signalEmitted() does not. This ensures the
// property cache is updated before the callbacks are invoked.
invokeSignalCallbacks(signalName, signals[signalName]);
}
}

this.signalEmitted = function (signalName, signalArgs) {
invokeSignalCallbacks(signalName, this.unwrapQObject(signalArgs));
}

function addMethod(methodData) {
var methodName = methodData[0];
var methodIdx = methodData[1];

// Fully specified methods are invoked by id, others by name for host-side overload resolution
var invokedMethod = methodName[methodName.length - 1] === ')' ? methodIdx : methodName

object[methodName] = function () {
var args = [];
var callback;
var errCallback;
for (var i = 0; i < arguments.length; ++i) {
var argument = arguments[i];
if (typeof argument === "function")
callback = argument;
else
args.push(argument);
}

var result;
// during test, webChannel.exec synchronously calls the callback
// therefore, the promise must be constucted before calling
// webChannel.exec to ensure the callback is set up
if (!callback && (typeof (Promise) === 'function')) {
result = new Promise(function (resolve, reject) {
callback = resolve;
errCallback = reject;
});
}

webChannel.exec({
"type": QWebChannelMessageTypes.invokeMethod,
"object": object.__id__,
"method": invokedMethod,
"args": args
}, function (response) {
if (response !== undefined) {
var result = object.unwrapQObject(response);
if (callback) {
(callback)(result);
}
} else if (errCallback) {
(errCallback)();
}
});

return result;
};
}

function bindGetterSetter(propertyInfo) {
var propertyIndex = propertyInfo[0];
var propertyName = propertyInfo[1];
var notifySignalData = propertyInfo[2];
// initialize property cache with current value
// NOTE: if this is an object, it is not directly unwrapped as it might
// reference other QObject that we do not know yet
object.__propertyCache__[propertyIndex] = propertyInfo[3];

if (notifySignalData) {
if (notifySignalData[0] === 1) {
// signal name is optimized away, reconstruct the actual name
notifySignalData[0] = propertyName + "Changed";
}
addSignal(notifySignalData, true);
}

Object.defineProperty(object, propertyName, {
configurable: true,
get: function () {
var propertyValue = object.__propertyCache__[propertyIndex];
if (propertyValue === undefined) {
// This shouldn't happen
console.warn("Undefined value in property cache for property \"" + propertyName + "\" in object " + object.__id__);
}

return propertyValue;
},
set: function (value) {
if (value === undefined) {
console.warn("Property setter for " + propertyName + " called with undefined value!");
return;
}
object.__propertyCache__[propertyIndex] = value;
var valueToSend = value;
webChannel.exec({
"type": QWebChannelMessageTypes.setProperty,
"object": object.__id__,
"property": propertyIndex,
"value": valueToSend
});
}
});

}

// ----------------------------------------------------------------------

data.methods.forEach(addMethod);

data.properties.forEach(bindGetterSetter);

data.signals.forEach(function (signal) { addSignal(signal, false); });

Object.assign(object, data.enums);
}

QObject.prototype.toJSON = function () {
if (this.__id__ === undefined) return {};
return {
id: this.__id__,
"__QObject*__": true
};
};

//required for use with nodejs
if (typeof module === 'object') {
module.exports = {
QWebChannel: QWebChannel
};
}

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