Qt封装HTML网页及数据交互（通信）
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2022-07-13 13:38:01
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看到网上有个关于Qt封装网页的例子，CSDN下载需要50积分（我呸 ....）。其实也是人家Qt官网给的demo，然后改了一丢丢而已。既然这样，那我也实现一下，而且提供源码。
【环境】Qt5.13 + MINGW
【要点】Qt GUI 、QWebEngine、QWebEngineView、QWebChannel、JS/HTML
窗体分为两个部分，左侧为QtGUi常用控件，右侧则是通过QWebEngineView加载显示的HTML页面。
其他的不做过多介绍。我们看一下主要代码实现部分。源码下载直接看链接。
// main.cpp
#include "dialog.h"
#include "core.h"
#include "../shared/websocketclientwrapper.h"
#include "../shared/websockettransport.h"
#include <QApplication>
#include <QDesktopServices>
#include <QDialog>
#include <QDir>
#include <QFileInfo>
#include <QUrl>
#include <QWebChannel>
#include <QWebSocketServer>
int main(int argc, char** argv)
{
QApplication app(argc, argv);
QFileInfo jsFileInfo(QDir::currentPath() + "/qwebchannel.js");
if (!jsFileInfo.exists())
QFile::copy(":/qtwebchannel/qwebchannel.js",jsFileInfo.absoluteFilePath());
// setup the QWebSocketServer
QWebSocketServer server(QStringLiteral("QWebChannel Standalone Example Server"), QWebSocketServer::NonSecureMode);
if (!server.listen(QHostAddress::LocalHost, 12345)) {
qFatal("Failed to open web socket server.");
return 1;
}
// wrap WebSocket clients in QWebChannelAbstractTransport objects
WebSocketClientWrapper clientWrapper(&server);
// setup the channel
QWebChannel channel;
QObject::connect(&clientWrapper, &WebSocketClientWrapper::clientConnected,
&channel, &QWebChannel::connectTo);
// setup the UI
Dialog dialog;
// setup the core and publish it to the QWebChannel
Core core(&dialog);
channel.registerObject(QStringLiteral("core"), &core);
#if 0
// open a browser window with the client HTML page
QUrl url = QUrl::fromLocalFile(BUILD_DIR "/index.html");
QDesktopServices::openUrl(url);
dialog.displayMessage(Dialog::tr("Initialization complete, opening browser at %1.").arg(url.toDisplayString()));
#endif
dialog.show();
return app.exec();
}
// core.h
#ifndef CORE_H
#define CORE_H
#include "dialog.h"
#include <QObject>
/*
An instance of this class gets published over the WebChannel and is then accessible to HTML clients.
*/
class Core : public QObject
{
Q_OBJECT
public:
Core(Dialog *dialog, QObject *parent = nullptr)
: QObject(parent), m_dialog(dialog)
{
connect(dialog, &Dialog::sendText, this, &Core::sendText);
}
signals:
/*
This signal is emitted from the C++ side and the text displayed on the HTML client side.
*/
void sendText(const QString &text);
public slots:
/*
This slot is invoked from the HTML client side and the text displayed on the server side.
*/
void receiveText(const QString &text)
{
m_dialog->displayMessage(Dialog::tr("Received message: %1").arg(text));
}
private:
Dialog *m_dialog;
};
#endif // CORE_H
//dialog.h
#ifndef DIALOG_H
#define DIALOG_H
#include <QDialog>
QT_BEGIN_NAMESPACE
namespace Ui {
class Dialog;
}
QT_END_NAMESPACE
class Dialog : public QDialog
{
Q_OBJECT
public:
explicit Dialog(QWidget *parent = nullptr);
void displayMessage(const QString &message);
signals:
void sendText(const QString &text);
private slots:
void clicked();
private:
Ui::Dialog *ui;
};
#endif // DIALOG_H
// dialog.cpp
#include "dialog.h"
#include "ui_dialog.h"
#include <QWebEngineView>
Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
connect(ui->send, &QPushButton::clicked, this, &Dialog::clicked);
// 使用Qt控件显示网页
QWebEngineView *view = new QWebEngineView(ui->widget);
view->resize(490,490);
view->load(QUrl(BUILD_DIR "/index.html"));
view->show();
}
void Dialog::displayMessage(const QString &message)
{
ui->output->appendPlainText(message);
}
void Dialog::clicked()
{
const QString text = ui->input->text();
if (text.isEmpty())
return;
emit sendText(text);
displayMessage(tr("Sent message: %1").arg(text));
ui->input->clear();
}
[index.html]
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript" src="./qwebchannel.js"></script>
<script type="text/javascript">
//BEGIN SETUP
function output(message) {
var output = document.getElementById("output");
output.innerHTML = output.innerHTML + message + "\n";
}
window.onload = function() {
if (location.search != "")
var baseUrl = (/[?&]webChannelBaseUrl=([A-Za-z0-9\-:/\.]+)/.exec(location.search)[1]);
else
var baseUrl = "ws://localhost:12345";
output("Connecting to WebSocket server at " + baseUrl + ".");
var socket = new WebSocket(baseUrl);
socket.onclose = function() {
console.error("web channel closed");
};
socket.onerror = function(error) {
console.error("web channel error: " + error);
};
socket.onopen = function() {
output("WebSocket connected, setting up QWebChannel.");
new QWebChannel(socket, function(channel) {
// make core object accessible globally
window.core = channel.objects.core;
document.getElementById("send").onclick = function() {
var input = document.getElementById("input");
var text = input.value;
if (!text) {
return;
}
output("Sent message: " + text);
input.value = "";
core.receiveText(text);
}
core.sendText.connect(function(message) {
output("Received message: " + message);
});
core.receiveText("Client connected, ready to send/receive messages!");
output("Connected to WebChannel, ready to send/receive messages!");
});
}
}
//END SETUP
</script>
<style type="text/css">
html {
height: 100%;
width: 100%;
}
#input {
width: 300px;
margin: 0 10px 0 0;
}
#send {
width: 90px;
margin: 0;
}
#output {
width: 500px;
height: 300px;
}
</style>
</head>
<body>
<textarea id="output"></textarea><br />
<input id="input" /><input type="submit" id="send" value="Send" οnclick="javascript:click();" />
</body>
</html>
[qwebchannel.js]
"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)
{
for (var i in message.data) {
var data = message.data[i];
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 (var objectName in data) {
var object = new QObject(objectName, data[objectName], channel);
}
// now unwrap properties, which might reference other registered objects
for (var objectName in 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
var ret = new Array(response.length);
for (var i = 0; i < response.length; ++i) {
ret[i] = object.unwrapQObject(response[i]);
}
return ret;
}
if (!response
|| !response["__QObject*__"]
|| response.id === undefined) {
return response;
}
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
var propertyNames = [];
for (var propertyName in qObject) {
propertyNames.push(propertyName);
}
for (var idx in propertyNames) {
delete qObject[propertyNames[idx]];
}
}
});
// here we are already initialized, and thus must directly unwrap the properties
qObject.unwrapProperties();
return qObject;
}
this.unwrapProperties = function()
{
for (var propertyIdx in 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);
if (!isPropertyNotifySignal && signalName !== "destroyed") {
// only required for "pure" signals, handled separately for properties in propertyUpdate
// also note that we always get notified about the destroyed signal
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;
}
object.__objectSignals__[signalIndex] = object.__objectSignals__[signalIndex] || [];
var idx = object.__objectSignals__[signalIndex].indexOf(callback);
if (idx === -1) {
console.error("Cannot find connection of signal " + signalName + " to " + callback.name);
return;
}
object.__objectSignals__[signalIndex].splice(idx, 1);
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 (var propertyIndex in propertyMap) {
var propertyValue = propertyMap[propertyIndex];
object.__propertyCache__[propertyIndex] = propertyValue;
}
for (var signalName in 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];
object[methodName] = function() {
var args = [];
var callback;
for (var i = 0; i < arguments.length; ++i) {
var argument = arguments[i];
if (typeof argument === "function")
callback = argument;
else if (argument instanceof QObject && webChannel.objects[argument.__id__] !== undefined)
args.push({
"id": argument.__id__
});
else
args.push(argument);
}
webChannel.exec({
"type": QWebChannelMessageTypes.invokeMethod,
"object": object.__id__,
"method": methodIdx,
"args": args
}, function(response) {
if (response !== undefined) {
var result = object.unwrapQObject(response);
if (callback) {
(callback)(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;
if (valueToSend instanceof QObject && webChannel.objects[valueToSend.__id__] !== undefined)
valueToSend = { "id": valueToSend.__id__ };
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); });
for (var name in data.enums) {
object[name] = data.enums[name];
}
}
//required for use with nodejs
if (typeof module === 'object') {
module.exports = {
QWebChannel: QWebChannel
};
}
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