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SetProperty vs setContextProperty
Clint Westwood last edited by
I'm using qt quick controls 1.3. I have a working setup for communication between c++ and qml, but there are some things that I'd like to change which give me errors if I apply these changes. So I'd like to clear up a few things.
My test program does the following: When I press a button some text appears in the text area.
This is my class from myclass.h:
class menu_items : public QObject
void set_text ();
In my main function I find pointers to QObject "text" and "button" and fill this class with them.
This is set_text function from myclass.cpp:
text->setProperty("text", "This is text!");
To change text I use setProperty. To assign function to button I use setContextProperty. This is code from main.cpp:
QQmlContext* ctx = engine.rootContext();
And this is qml code for my button:
text: qsTr("Press Me 1")
//onClicked: messageDialog.show(qsTr("You've pressed a button!"));
This works alright, but I'd like to know why some particular changes give me errors:
- When assigning a function to button I have to use setContextProperty. However, I want to use setProperty instead. But if I use something like
Compiler fails with error:
@c2102 & requires l-value@
I want to use setProperty instead of setContextProperty because that way I don't have to edit qml file. In my current setup I had to specify onClicked event in qml. If it's possible, I'd like to be able fully control qml from c++ without having to edit qml.
- My class is in header file and class functions are in separate cpp file. I'd like to move everything to main cpp, but if I do that I get linker errors. Is header-cpp class structure mandatory for communication between qml adn c++?
Here are error codes:
LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall menu_items::metaObject(void)const " (?metaObject@menu_items@@UBEPBUQMetaObject@@XZ)
LNK2001: unresolved external symbol "public: virtual void * __thiscall menu_items::qt_metacast(char const *)" (?qt_metacast@menu_items@@UAEPAXPBD@Z)
LNK2001: unresolved external symbol "public: virtual int __thiscall menu_items::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@menu_items@@UAEHW4Call@QMetaObject@@HPAPAX@Z)