get the last QWidget actived
-
I found this signal : QApplication::focusChanged(QWidget *old, QWidget *new)
And it's work for what I want to do.
But, this function sends me the most little child of all my widgets. So I have implemented this function :template <class T>T findParent(QObject *child) { T r = 0; if (!child) return nullptr; QObject *parent = child->parent(); while (parent) { r = dynamic_cast<T> (parent); if (r) return r; parent = parent->parent(); } return r; }And it's working with "findParent<LayoutPanelTabber *>(new);"
Thanks -
@mrjj
Hi yes but I have some problems with qobject_cast :
"Error C2338 qobject_cast requires the type to have a Q_OBJECT macro"
But in my class, I have the macro :class ProjectManager : public QObject { Q_OBJECT public: // Some function... template <class T> T findParent(QObject *child) { T r = nullptr; if (!child) return nullptr; QObject *parent = child->parent(); while (parent) { r = qobject_cast<T>(parent); if (r) return r; parent = parent->parent(); } return r; } };Sorry for my English ^^'
-
@mrjj
Hi yes but I have some problems with qobject_cast :
"Error C2338 qobject_cast requires the type to have a Q_OBJECT macro"
But in my class, I have the macro :class ProjectManager : public QObject { Q_OBJECT public: // Some function... template <class T> T findParent(QObject *child) { T r = nullptr; if (!child) return nullptr; QObject *parent = child->parent(); while (parent) { r = qobject_cast<T>(parent); if (r) return r; parent = parent->parent(); } return r; } };@bozo6919
I don't know what the answer is and I don't do C++, butr = qobject_cast<T>(parent);
"Error C2338 qobject_cast requires the type to have a Q_OBJECT macro"This will be complaining about the
Q_OBJECTonparentor on typeT(not sure which, perhaps the latter) not on your class, won't it? -
@bozo6919
I don't know what the answer is and I don't do C++, butr = qobject_cast<T>(parent);
"Error C2338 qobject_cast requires the type to have a Q_OBJECT macro"This will be complaining about the
Q_OBJECTonparentor on typeT(not sure which, perhaps the latter) not on your class, won't it? -
@bozo6919
Hi
Ah maybe it don't like templates as T don't exist yet.
So if static check, there is no way for it to know if contains Q_OBJECT
or not. -
Yes, it's what I was suspecting too, but in my class, if I call qobject_cast with T = ContentPanelEditor *, who is contained in the same project and have the macro Q_OBJECT, I have the same error...
Edit:
No, I misread. ^^' after the qobject_cast on my ContentPanelEditor, I have another cast for a class in another project. So he doesn't know about this class.
This other class is contained in a dll. There is a way to apply qobject_cast on it? -
Hi,
Can you give more details about that chain of casts ?
-
Hi,
My program has two projects :
- one is a DLL.
- the other an EXE.
In my EXE, I have to apply a qobject_cast on a class who is contained in my DLL.
But if I put in this class (in the DLL) the macro Q_OBJECT, my IDE (visual studio 2017) cannot compile the project with an error of linking.
-
Is your .dll project also managed with Qt ?
-
Then there should be no problem with
qobject_cast. -
What exact problems ?
-
Hi, sorry for my late
This problem for example :
#pragma once #include <QtCore/qobject.h> class __declspec(dllexport) LayoutManager : public QObject { Q_OBJECT public: template <class T>T findParent(QObject *child) { T r = nullptr; if (!child) return nullptr; QObject *parent = child->parent(); while (parent) { r = qobject_cast<T>(parent); if (r) return r; parent = parent->parent(); } return r; } };And I have this error message :
Error : C2338 : qobject_cast requires the type to have a Q_OBJECT macroBut the macro is here. So instead of qobject_cast, I have to use dynamic_cast
-
What type are you looking for ?
-
And is that type a QObject based class with
Q_OBJECTin it's declaration ?@bozo6919 said in get the last QWidget actived:
class __declspec(dllexport) LayoutManager : public QObject
On a side note, Qt provides macros to properly handle the export/import stuff. See here.
