基于QT QWebEnginePage :: setWebChannel()传输对象和Qt:无法从javascript调用共享对象方法/属性我试图制作一个小型演示来测试功能.请参阅下面的基本测试代码.我的问题是:
.pro文件
QT += core gui
QT += network webenginewidgets webchannel widgets
TARGET = hfbTestWebChannel
TEMPLATE = app
SOURCES += hfbTestWebChannel.cpp
RESOURCES += hfbTestWebChannel.qrc
.html文件
<html>
<body>
<script type="text/javascript" src="qrc:///qtwebchannel/qwebchannel.js"></script>
<script type="text/javascript">
var theQtObj;
function buttonA()
{
PrintLog("Button A:init")
if (typeof qt !== "undefined")
{
new QWebChannel(qt.webChannelTransport, function(channel)
{
theQtObj = channel.objects.theQtObj;
PrintLog(" done, now theQtObj=" + theQtObj.toString());
});
}
else
PrintLog("!!!qt undefined!!!" );
}
function buttonB()
{
PrintLog("Button B : call c++ and get some answers!")
if(typeof theQtObj !== "undefined")
{
var X = prompt("Enter a number", "5");
PrintLog("theQtObj=" + theQtObj + " => X=" + X);
var n = theQtObj.getInt(X);
PrintLog(" back in js with n="+n);
var d = theQtObj.getDouble(n);
PrintLog(" back in js with d="+d);
var s = theQtObj.getString(d.toString());
PrintLog("X:" + X + "->" + n + "->" + d + "->" + s);
}
else
PrintLog(" --> theQtObj not defined");
}
function buttonC()
{
PrintLog("Button C:get c++ object member elements")
if(typeof theQtObj !== "undefined")
{
PrintLog("theQtObj._theString=" + theQtObj._theString);
PrintLog("theQtObj._theInt=" + theQtObj._theInt);
}
else
PrintLog(" --> theQtObj not defined");
}
var x=0;
function PrintLog(txt)
{
var myBox = document.getElementById("textBoxLog");
myBox.value += ("\n" + x + ": " + txt);
myBox.scrollTop = myBox.scrollHeight;
return (x++);
}
</script>
<p>Test Example to call Qt function from Javascript </p>
<p>
<input type="button" value=" A:init " onclick="buttonA()">
<input type="button" value=" B:get int " onclick="buttonB()">
<input type="button" value="C:get members" onclick="buttonC()">
</p>
<p>
<textarea id="textBoxLog" rows="31" cols="95">
textBoxLog
</textarea>
</p>
</body>
</html>
.cpp文件
#include <QWebEngineView>
#include <QApplication>
#include <QtWebChannel/QtWebChannel>
/////////////////////////////////////////////////////////////////
class hfbDisplayWidget : public QWebEngineView
{
Q_OBJECT
public:
hfbDisplayWidget(QWidget * parent) : QWebEngineView(parent)
{
page()->setWebChannel(&_webchannel);
_webchannel.registerObject(QString("theQtObj"), this);
_theString = "Hello World";
_theInt = 777;
}
QWebChannel _webchannel;
Q_INVOKABLE QString _theString;
Q_INVOKABLE int _theInt;
Q_INVOKABLE int getInt(QVariant n)
{
int N = n.toInt();
QString js = QString("PrintLog('c++ getInt(%1) fired!')").arg(N);
_theString = js;
_theInt = N;
page()->runJavaScript(js, [=](const QVariant &rslt){
qDebug() << js << " -> " << rslt;
});
return N*100;
}
Q_INVOKABLE double getDouble(QVariant d)
{
double D = d.toDouble();
QString js = QString("PrintLog('c++ getDouble(%1) fired!')").arg(D);
page()->runJavaScript(js, [=](const QVariant &rslt){
qDebug() << js << " -> " << rslt;
});
return (D+0.12345);
}
Q_INVOKABLE QString getString(QVariant s)
{
QString S = s.toString();
QString js = QString("PrintLog('c++ getString(%1) fired!')").arg(S);
page()->runJavaScript(js, [=](const QVariant &rslt){
qDebug() << js << " -> " << rslt;
});
return (QString("c++ called with:'") + S + QString("'"));
}
};
/////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
hfbDisplayWidget view(nullptr);
view.setUrl(QUrl("qrc:/hfbTestWebChannel.html"));
view.show();
return a.exec();
}
/////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////
#include "hfbTestWebChannel.moc"
*编辑添加所有代码的完整性
小智 5
面临同样的问题......仔细阅读文档给了我答案。答案是Qt5中Qt和JS之间的通信是异步的。您必须提供回调函数，该函数将在方法完成并收到结果值后调用。
而不是打电话
var n = theQtObj.getInt(X);
PrintLog(" back in js with n="+n);
您可以拨打 as
theQtObj.getInt(X, function(n) {
PrintLog(" back in js with n="+n);
});
我最近也遇到了同样的问题。经过一番调查后，我弄清楚了如何让它发挥作用。非常感谢这个问题的回答：How to use Qt WebEngine and QWebChannel?
为了获取 QObject 方法的返回值，您需要定义一个包装 QObject 方法的 Q_PROPERTY。例如：
class SharedObject : public QObject
{
Q_OBJECT
public:
Q_INVOKABLE int getIntValue();
Q_PROPERTY(int intValue READ getIntValue)
Q_INVOKABLE QString getStringValue();
Q_PROPERTY(QString stringValue READ getStringValue)
}
然后在 HTML 中执行以下操作：
<script type="text/javascript">
document.addEventListener("DOMContentLoaded", function () {
new QWebChannel(qt.webChannelTransport, function (channel) {
window.sharedObject = channel.objects.sharedObject;
alert("intValue: " + sharedObject.intValue);
alert("stringValue: " + sharedObject.stringValue);
});
});
</script>
您应该能够在 JavaScript 代码中看到 intValue 和 stringValue。我认为重要的是使用 Q_PROPERTY 。
无论如何，这解决了我的问题，我希望它对其他人也有帮助。