CODEWITHSUNDEEP
qtwebkitbridge
jmc
jmc

Reputation: 31

Qt Webkit Bridge: C++ access to JavaScript

I am using a QWebView and call to setHtml() to display some HTML/JavaScript pages. I am passing data updates using QWebFrame::evaluateJavaScript by passing it a QString containing a call to a JavaScript function (with arguments). After reading about the Qt WebKit Bridge I feel like there should be a better way to do his. I see discussion of exposing Qt objects / functions in C++ to the JavaScript, but not the other direction. (I do not want the JavaScript to poll the C++ side for updates.) Is there a way to connect a JavaScript function as a slot to a Qt/C++ signal? (Or a similar pattern) I feel like I have looked through a lot of docs, posted questions (even the 'Similar Questions' as I type this), but have not seen examples of this. Appreciate any info, links or nudges in the right direction.

Upvotes: 3

Views: 2068

Answers (1)

user2554528
user2554528

Reputation:

Use addToJavaScriptWindow object for exposing your C++ objects the Javascript tier:

page()->mainFrame()->addToJavaScriptWindowObject(QString("myObject"), myObject);

Check documentation here: http://qt-project.org/doc/qt-4.8/qwebframe.html#addToJavaScriptWindowObject

That will expose your C++ myObject as "myObject".

Then, you can do exactly what you are looking for on your post, let's suppose myObject declares a signal in the following way:

signal:

mySignal(QString aParameter);

you can simply connect that signal to a slot on your web side as follows:

myObject.mySignal.connect(this, this.mySignalSlot);

In this case, mySignalSlot should have the same signature than mySignal declaration at the C++ class side (well, "same signature" would mean same number of parameters as javascript is not typed, so you won't need to declare a type for each of them).

What's really usefull here is to pass JSon objects. In case you need to pass big amount of data you can use base64 encoding. For images, QTWebKit supports natively QImage and QPixmap classes; these last two are natively encoded as complex javascript objects by QTWebKit Bridge engine.

Upvotes: 2

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