Is it possible to call a C++ function from JavaScript in a QWebView?

Question

I have a web page loaded in a QWebView. In there, I would like to have JavaScript call a function of my application. That function would then returns some strings that JavaScript would dynamically display.

Can it be done using QWebView? Basically, is it possible to have some bridge between the application (in C++) and the QWebView control?

Least

Answer 1

This is how I ended up doing it. I declared a "JavaScriptBridge" class in my header file with a Q_INVOKABLE method. Q_INVOKABLE methods can be called from JavaScript:

class DictionaryJavaScriptBridge : public QObject {

    Q_OBJECT

public:

    DictionaryJavaScriptBridge(DictionaryWidget* dictionaryWidget); 
    Q_INVOKABLE QStringList sentences(QString characters);

private:

    DictionaryWidget* dictionaryWidget_;

};

Then in my .cpp file, I create the bridge:

jsBridge_ = new DictionaryJavaScriptBridge(this);

And I listen to the javaScriptWindowObjectCleared signal. This step is important because WebKit is going to clear all the JavaScript objects when loading a new page, so you need to add back the bridge every time:

connect(ui->webView->page()->mainFrame(), SIGNAL(javaScriptWindowObjectCleared()), this, SLOT(mainFrame_javaScriptWindowObjectCleared()));

Finally, in the javaScriptWindowObjectCleared slot, I add the JavaScript bridge:

void DictionaryWidget::mainFrame_javaScriptWindowObjectCleared() {
    ui->webView->page()->mainFrame()->addToJavaScriptWindowObject("ehbridge", jsBridge_);
}

Now from JavaScript, there will be a global "ehbridge" object exposed. I can call its methods like a normal JavaScript object (Qt converts Qt's types to JavaScript types)

var sentences = ehbridge.sentences("test");

Least

To be 100% accurate, Q_INVOKABLE just creates a slot, so you can dynamically invoke any public slot of any class. Still, it might be more clear semantically if you are using Q_INVOKABLE that the method is intended for calling from "outside". – Repute

+1 for reestablishing the bridge every time on javaScriptWindowObjectCleared – Harlem