In my code, I have a Gtkmm Gtk::Window* and I wanna access it's widgets frequently. How can I do it?
What I mean is to see if there's any feature like Builder->get_widget(). Thanks for helps.
Not really. There are some methods for finding children of a widget, but it's a colossal pain.
Personally, I always subclass Gtk::Window and make public (or make public functions) if I need to mess with any widgets outside the class.
Gtk::Bin class where get_child() is: http://developer.gnome.org/gtkmm/unstable/classGtk_1_1Bin.html#a8e7fef9251afa541318bb53dcf3098db
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I'm new to Qt and fairly new to C++ but I need help with this issue.
I have a custom class called HybridStack and I want it to extend a QStackedWidget and a QMainWindow.
I want it to extend a QStackedWidget so that I can use as many pages as I need and I want it to extend a QMainWindow so that I could be able to make each page have it's own MenuBar with different content of menu for different page.
I want to add this custom class HybridStack to Qt Designer by
promoting it from a QStackedWidget.
Is this possible? If it is, can you brief me on how to do this? If it's not possible then what's an alternative? Most importantly, I need to use it in the Designer because I need to use qmake
You can't derive from both QStackedWidget and QMainWindow, because both of those are in turn derived from QWidget. If you did so, you'd end up with the Dreaded Diamond. You'll have to use composition instead.
Even then, I'm not sure if it would work correctly to put a QMainWindow within a QStackedWidget, since it is designed to be a top-level item (i.e. its shown directly as a window, not embedded within another QWidget). Another way of accomplishing what you want (menu bar changing when the you change tabs) would be the following:
Make your top-level item a QMainWindow
Make the central widget a custom widget derived from QStackedWidget
When the item showing in the stack widget changes, you can call QMainWindow::setMenuBar to change the menu bar. Each widget within the QStackWidget could have its own QMenuBar instance that it uses for this purpose.
I wanted to know how I can gain access to the sectionsInserted slot.I need access to the parameters of that method. Since it is a protected slot I think I would need to inherit from QHeaderView. Now even if I inherit from QheaderView how would I attach that Qheaderview to my tableview ?
You can set the vertical and horizontal headers of a QTableView with QTableView::setVerticalHeader() and QTableView::setHorizontalHeader(), respectively.
You should use QAbstractItemModel::columnsInserted or QAbstractItemModel::rowsInserted signals instead. They have exactly the same signature. I believe they are connected to the QHeaderView::sectionsInserted slot.
Subclassing QHeaderView will not help you. QHeaderView::columnsInserted is not virtual, so your implementation will not be called by Qt.
I have a utility class in my Qt GUI application. However, in my convenience class I wanted to call a QMessageBox::critical(), warning(), etc. The class isn't a QWidget, and therefore I cannot pass this as the parent. My class is subclassed from QObject, however, so it can run things such as signals and slots. So to work around this--if it's possible to--should I maybe look at the property API instead of using the Static API?
Class declaration:
class NetworkManager : public QObject
And here's an example of a Static API call that fails:
QMessageBox::critical(this, tr("Network"), tr("Unable to connect to host.\n"),
QMessageBox::Ok | QMessageBox::Discard);
So, if I were to build a Property based API message box, would it be possible to call it in a QObject somehow? I haven't really used the Property Based API, but I understand from the documentation that it seems to use an event loop (i.e. exec()).
Just pass NULL for the first parameter:
QMessageBox::critical(NULL, QObject::tr("Error"), QObject::tr("..."));
A better way than passing nullptr is to use the qobject tree you are already using (assuming that the parent of the NetworkManager instance is a QWidget; adjust the number of parents according to whatever your qobject tree looks like)
QMessageBox::critical(qobject_cast<QWidget *> (parent()), "Title", "Message");
We use a qobject_cast<> instead of a C or C++ style cast is because it adds a little protection and will return 0 if it can't cast upward to the QWidget *.
If you use nullptr the QMessageBox will appear as centered over the topmost window (QWidget) rather than the window that actually appeared higher up in the qobject tree of your NetworkManager class. This really annoys people who have multiple monitors, lots of windows open, multiple windows from a single application spanning multiple monitors, etc.
I use Qt designer to make an interface and I have an QWebView in it. I would like to reimplement the fonction mouseDoubleClickEvent of my QWebView.
Can I do that? I know I have to use ui->webview to access it, I know I can use the signals easily with on_webView_selectionChanged for example, but what about other methods like mouseDoubleClickEvent?
Since mouseDoubleCLickEvent is a virtual protected function, you will need to subclass QWebView and re-implement the method in your subclass. The documentation for mouseDoubleClickEvent, a method of QWidget, can be found here. After this, you will probably want to integrate your custom widget with Qt Designer. I am not familiar with the program, but this documentation might prove useful. (Edit: it appears that promoting a custom subclass of QWebView requires additional steps which are documented here and here) I do not know of any pure GUI method for creating the custom subclass you need.
I am porting an application from Qt3 to Qt4, and need a Qt4 replacement for QApplication::mainWidget() which used to return the top-level widget in Qt3. Does anyone know how to do this in Qt4?
Technically, any widget initialized with NULL is a top level widget so QApplication shouldn't assume that one of them is better than another.
The way I usually do it is to save a pointer to the "real" main widget somewhere, even a global variable or a singleton and reference it when needed.
I think topLevelWidgets() is as close at it can be.
Edit:
Yup. Qt4 added complexity (and power). There is no application wide MainWidget anymore. Many QMainWindows can be created and shown, and hidden, and shown again. This is a good thing, though :)
As shoosh noticed, QT3 behaviour can be easily simulated with global variable (yuck!) or QApplication subclass.
I think what you're looking for has been replaced by the QMainWindow class, which does allow you to set a set and get a central widget.