The QMainWindow is the main window in a Qt application. So usually you'd have only one, but would it be possible at all to have multiple QMainWindow instances in your application?
I am working on integrating a Qt-based GUI application B into another Qt-based GUI application A. Both these applications have a QMainWindow, and I was considering as a first step to create a new QMainWindow that has both old QMainWindows on tabs. That way it would allow me to concentrate on wiring the backend of GUI B to the backend of A without having to change anything in the user interface itself. Is this a viable approach, or do you have other suggestions?
You can have as many QMainWindow instances as you want. A QMainWindow is just a QWidget which provides a menu bar, toolbar, status bar and docking framework. But basically it is just a QWidget so you can have as many as you like.
Normally you only have a single QMainWindow for GUI design reasons since it can be confusing to have multiple main windows. However, when implementing applications like QtAssistant which can open a new instance of themselves then the one process has multiple main windows.
What you suggest should work. The window with the tabs would not need to be a QMainWindow unless you want to also want add a toolbar to that window as well.
Related
In C# there are controllers which takes a GUI element and everything in it to be able to use in multiple places at the same time, does Qt have the same thing?
In my case I have various Groupboxes with with textEdits which I need to fill depending on some options. Currently I tried a QStackedWidget but the contents cant have the same objectname so it I cant fill the textEdits as easily.
How should I go about to generalize it?
in qt the same, you can always "move" widgets from one layout to another,
and if you are using qt creator, then widgets in editor are inserted in the ui so you can always have access to them by its name..
for example:
namespace Ui
{
class MainWindow;
}
class MainWindow : public QMainWindow
you will have some private member Ui::MainWindow* ui{nullptr}; and there you can get the labels you inserted in the main window doing:
ui->myLabel->setText(.....
or
ui->myButton->setEnable(....
I'm attempting to run different modes/states of my app, for example having a menu which can go to a game state then highscore and from those two back to menu.
A solution I tried was using the autogenerated class QMainWindow as a superclass for creating the classes Menu and Game to start with. In QMainWindow I later want to create a QMainWindow, fill it with a Menu or Game and in eg. QMainWindow.paintEvents() call Menu.paintEvent() through polymophfism.
Now I know that I can't create a QMainWindow in another QMainWindow but would this idea work with yet another subclass called states or somthing inbetween the existing super/subclass(es)?
I was able to run just Game by itself (instead of QMainWindow) so the inheritance is probably done right. But when trying to create and run only a Game in QMainWindow it gave me a sigsegv at QMainWindow's constructor (which I have not changed and runs completely fine bby itself if empty). I've solved the problem with the classes including themselves in one another so that's not the problem either.
I solved it by making a superclass "State" for menu and game (without making State a subclass to QMainWindow) which is called by QMainWindow for each operation.
This is essentially the "states" pattern which I realise existed after the implementation.
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.
All I would like to do is to be able to open a new dialog from my MainWindow. I want to be able to design the dialog in Qt designer and then use the signals and slots editor to link a button press in my main window to the display of a new dialog. The dialog needs to have a couple of line edits and buttons in it and I want to avoid writing a new class in C++ every time i want a different dialog.
How can I link my main window to another dialog i created in qt designer?
You won't be able to connect the signal to startup the dialog within the designer, this will have to be in the code. But you won't need a new custom class everytime, you could easily use one class implementing different widgets.
You will have to write some c++/design some dialog everytime, since you do want to have another dialog (or at least another setup in the same dialog). You could setup the dialog to have a QStackedWidget and have an index in the constructor for having one dialog with multiple pages.
I'm coding a simple text editor with only few basic features.
At the moment it has a QMainWindow with QTabWidget set as it's centralWidget.
What I'm implementing now are some shortcuts; ctrl+s to save, ctrl+o to open, and ctrl+t/ctrl+w to create a new tab/close the current tab.
I know how to implement all the features, but the question is where to implement the features?
Should all the shortcuts be members of QMainWindow and let it take care of everything, or should I try separating the shortcuts into their correspoding classes?
For example, creating a new tab (ctrl+t) would be part of QTabWidget.
Now what about ctrl+s (save, duh), should it be part of QTextEdit since it's the text I'm saving, or..?
Basically my program contains three classes; QMainWindow, which contains QTabWidget, and each tab is a QTextEdit.
Your setup sounds a lot like many of the applications I've built.
I generally handle shortcuts via the QAction::setShortcut() method, so it's really more about where does it make sense to store the QAction objects. This usually ends up being my MainWindow class as a lot of the actions are all used in the MainWindw's menus. When these actions are triggered, the result is usually that the TabWidget is notified which in turn notifies all the necessary tabs and can handle things like a "Close All" action triggering only one save prompt.
However, if it doesn't make sense to store those QActions on the MainWindow object, then I don't, as in the case of the context menu I usually have available on my individual tabs.
Hope that helps.