Hi, 2013/5/4 superpelican <superpeli...@zoho.com>: > I'm writing a QML/Sailfish Silica app that will use the logic of a CLI C++ > application I had already written. I've also already created a QML/Silica > UI. So I will need to let C++ and QML communicate (for example the C++ code > has to know when a QML Button is clicked) > > and the C++ code will need to change the properties (for example text of a > label) of QML items. > [...] > However the Sailfish example application (on which I based my app) is > initialized differently than a normal QML application (like those on the Qt > Docs). So does the Sailfish example application (I mean the > sailfishapplication.cpp and main.cpp parts) create a QDeclarativeEngine > object?
I haven't tried the Sailfish example application (just created a fullscreen QDeclarativeView myself, which also works fine in Sailfish, as all "themeing" / behavior is done via QML Components, anyway). Basically, once you get ahold of a QDeclarativeView (let's say you get a pointer "QDeclarativeView *view" to it), you can get the root context of the view via view->rootContext() and on that you can then set context properties using context->setContextProperty(). Ideally you can set one QObject subclass that defines the interface between your C++ code and QML - the QML can then interact with that object. An example can be found here: https://github.com/harmattan/mustr/blob/master/mustr.cpp The "Wallpaper" object is my QObject subclass that interfaces C++ with QML: https://github.com/harmattan/mustr/blob/master/wallpaper.h For functions to be called from QML, they have to be slots or Q_INVOKABLE. You can communicate back to QML with either signals or properties. Here's how my QML looks: https://github.com/harmattan/mustr/blob/master/mustr.qml If you search for usages of the "wallpaper" object in there, you will see how to call C++ functions (that fulfills your "C++ code needs to know when a QML button was clicked" requirement): wallpaper.setPattern(previewPage.url) Also, for communicating back from C++, you can connect to signals of that object: Connections { target: wallpaper onDone: infoBanner.show() } Another example that also shows usage of properties and might be an even better example of interfacing existing C++ code with QML is here: https://github.com/harmattan/classicprintqml/blob/master/ClassicPrintDeclarative.h I've found it easiest to have one single instance of a QObject subclass exposed as context property that acts as the interface between QML and C++. Of course, there are also other approaches (qmlRegisterType(), etc..). As far as the sailfish example application goes, this might be helpful: http://blog.linux4us.org/2013/02/28/sailfishapplication-and-setcontextproperty/ HTH :) Thomas _______________________________________________ SailfishOS.org Devel mailing list
