Syntexs for Inheritance in C++

[zenghsing]

I am confuse for some syntex about the Inheritance in QML and C++.

It will show error message "qrc:/QML/Resources/Qml/DesignArea.qml:32: Error: Unknown method parameter type: AppGraphicsList"* when I run below code.

But I am sure I had include :AppGraphicsList.h" in File '".

Why???

%%% in main.cpp
AppGraphicsList * graphicPath = new AppGraphicsList();
int main(int argc, char *argv[])
{
...
ctext->setContextProperty("widget_graphicPath",graphicPath);
...
}

%%% in Design.qml

Component.onCompleted: {
mainWindow.setGraphicList(widget_graphicPath);
}
WorkArea{
id:mainWindow
objectName: "mainWin"
anchors.fill: parent
}

%%% in workarea.h
class WorkArea : public QQuickPaintedItem
{
Q_OBJECT
public:
WorkArea();
~WorkArea();
public slots:
void setGraphicList(AppGraphicsList *graphicPath);
}

%%% in graphicslist.h
class GraphicsList : public QObject
{
Q_OBJECT
public:
explicit GraphicsList(QObject *parent = 0);
...
}

%%% in AppGraphicsList.h
class AppGraphicsList:public GraphicsList
{
public:
// AppGraphicsList();
}

%%%

The werid thing is that code would be OK when I change " void setGraphicList(AppGraphicsList *graphicPath);"
to
" void setGraphicList(GraphicsList *graphicPath);".
as below code:

WHY???

%%% in main.cpp
AppGraphicsList * graphicPath = new AppGraphicsList();
int main(int argc, char *argv[])
{
...
ctext->setContextProperty("widget_graphicPath",graphicPath);
...
}

%%% in Design.qml

Component.onCompleted: {
mainWindow.setGraphicList(widget_graphicPath);
}
WorkArea{
id:mainWindow
objectName: "mainWin"
anchors.fill: parent
}

%%% in workarea.h
class WorkArea : public QQuickPaintedItem
{
Q_OBJECT
public:
WorkArea();
~WorkArea();
public slots:
void setGraphicList(GraphicsList *graphicPath);
}

%%% in graphicslist.h
class GraphicsList : public QObject
{
Q_OBJECT
public:
explicit GraphicsList(QObject *parent = 0);
...
}

%%% in AppGraphicsList.h
class AppGraphicsList:public GraphicsList
{
public:
// AppGraphicsList();
}

[raven-worx]

@zenghsing
Qt and especially the QML framework heavily depend on the meta object system for meta data.
The QML engine is missing some meta data about your AppGraphicsList class, because this class is missing the Q_OBJECT macro.

[zenghsing]

@raven-worx

Its true. Thanks~~~