[SailfishDevel] Alpha 2: passing simple properties from main.cpp to qml: A bug?

[Lucien XU]

Hello guys !

It might be useful to use qmlRegister**Type (uncreatable, singleton etc.) to 
expose C++ components to QML. But if you really want to use rootContext()-
>setContextProperty, you have to be cautious.

Actually, if you pass the qml file to the view before registering C++ 
components, the QML components won't be able to see the C++ ones, so you have 
to call setContextProperty before calling setSource (or calling the 
createView("main.qml") method).

You have to call the parameter-less method createView(), and then, call 
setView(QQuickView *, QString) to pass the source QML file.

But beware, there is a bug in the template. See 
https://lists.sailfishos.org/pipermail/devel/2013-August/000529.html.

Hopes it helps (because I'm not very clear in this mail)
Cheers,
Lucien

Le dimanche 4 août 2013 17:05:01 christopher.lamb at thurweb.ch a écrit :
> Hi Martin
> 
> Curiouser and Curiouser!
> 
> Just to be sure, I went back and tested your suggestion in a demo
> project based on the default "Hello Sailors" new project template.
> 
> Here I pass the c++ property cppproperty with the value "Hello World".
> In the QML FirstPage this is concatenated to the "Hello Sailors" label
> text.
> 
> I still get this error:
> file:///opt/sdk/setContextPropertyDemo/usr/share/setContextPropertyDemo/page
> s/FirstPage.qml:34: ReferenceError: cppproperty is not defined
> 
> Yet the app displays "Hello Sailors: Hello world".
> 
> So a property can be passed as you suggested, it can be used. The
> error must be wrong!
> 
> Chris
> 
> P.s you test the same by creating a default new Sailfish project, and
> replacing the main.cpp and FirstPage.qml with the code below.
> 
> 
> //start main.cpp
> #include <QGuiApplication>
> #include <QQuickView>
> #include <QQmlContext>
> 
> #include "sailfishapplication.h"
> 
> Q_DECL_EXPORT int main(int argc, char *argv[])
> {
>      QScopedPointer<QGuiApplication>
> app(Sailfish::createApplication(argc, argv));
>      QScopedPointer<QQuickView> view(Sailfish::createView("main.qml"));
>      view->rootContext()->setContextProperty("cppproperty",  "Hello world");
> Sailfish::showView(view.data());
> 
>      return app->exec();
> }
> //end main.cpp
> 
> 
> //start FirstPage.qml
> import QtQuick 2.0
> import Sailfish.Silica 1.0
> import Sailfish.Silica.theme 1.0
> 
> 
> Page {
>      id: page
> 
>      // To enable PullDownMenu, place our content in a SilicaFlickable
>      SilicaFlickable {
>          anchors.fill: parent
> 
>          // PullDownMenu and PushUpMenu must be declared in
> SilicaFlickable, SilicaListView or SilicaGridView
>          PullDownMenu {
>              MenuItem {
>                  text: "Show Page 2"
>                  onClicked: pageStack.push(Qt.resolvedUrl("SecondPage.qml"))
> }
>          }
> 
>          // Tell SilicaFlickable the height of its content.
>          contentHeight: childrenRect.height
> 
>          // Place our content in a Column.  The PageHeader is always
> placed at the top
>          // of the page, followed by our content.
>          Column {
>              width: page.width
>              spacing: Theme.paddingLarge
>              PageHeader {
>                  title: "UI Template"
>              }
>              Label {
>                  x: Theme.paddingLarge
>                  text: "Hello Sailors: " + cppproperty
>                  color: Theme.secondaryHighlightColor
>                  font.pixelSize: Theme.fontSizeLarge
>              }
>          }
>      }
> }
> //end FirstPage.qml
> 
> Zitat von "Martin Grimme" <martin.grimme at gmail.com>:
> > Hi,
> > 
> > you don't want to set the context property on the
> > QmlApplicationViewer, which was dead Nokia code to target Symbian and
> > Harmattan, anyway.
> > QmlApplicationViewer was derived from QmlView, where it got the
> > rootContext() method from.
> > 
> > With Qt5, QmlView was renamed to QQuickView. And when using the
> > 
> > functions from sailfishapplication.h, you get a QQuickView*, e.g.:
> >         QScopedPointer<QQuickView> view(Sailfish::createView("main.qml"));
> >         view->rootContext()->setContextProperty("platform", platformId);
> > 
> > Martin
> > 
> > 2013/8/4, christopher.lamb at thurweb.ch <christopher.lamb at thurweb.ch>:
> >> Hi all
> >> 
> >> What is the recommended way to pass simple c++ properties from the
> >> main.cpp to the QML part of a project using the Qt 5 Alpha?
> >> 
> >> In the good old days of the first Alpha, I used to do this Harmattan
> >> style using
> >> 
> >>      QmlApplicationViewer viewer;
> >>      viewer.rootContext()->setContextProperty("platform",  platformId);
> >> 
> >> This would make the c++ property platformId available to my qml code
> >> as the property platform.
> >> 
> >> Now with Qt5 / Alpha 2 the QmlApplicationViewer is no longer created.
> >> 
> >> The tutorial linked below suggests that the QmlApplicationViewer files
> >> could be ported to Qt5, so I guess I could grab these files from an
> >> old Harmattan project and do that.
> >> 
> >> https://qt-project.org/doc/qt-5.0/qtdoc/portingqmlapp.html
> >> 
> >> But somehow that feels like carting old baggage around.
> >> 
> >> Is their a Sailfish native way of doing the same?
> >> 
> >> Thanks
> >> 
> >> Chris
> >> 
> >> 
> >> 
> >> 
> >> _______________________________________________
> >> SailfishOS.org Devel mailing list
> 
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