I have started to play a little with Qt 4. And then I have come across a problem with the Qt Designer.
In the Signal/Slots editor I can only setup the connections that are listed there, and not all the slots are listed.
If I try to add it manualy in the .ui file, the connection would not work.
If I add it in the ui_*.h file it works fine, but then the connection is deleted when I change the design.
Does anyone have any good tips to how I can get around this bug? Or to ask another way:
How can I make the Qt Designer list all the available slots?
By default not all signals/slots are shown. You could try checking the "show signals and slots inheritied from ...." checkbox in the lower left hand corder of the "Configure Connection" dialog that comes up when you try to create a signal.
Beyond that, you can either do what Marcin said and use auto-connections, or manually write connect statements in the constructor of the object that uses the ui.
You might try to use uic's autoconnecting feature.
However you won't be able to see all available slots but if you use the same name in both Designer and code - they should automatically be connected.
Related
I have just completed my first Qt 5 project and I want to add an About dialog. Is there a default, and how do you use it? If not, what's the best way to add one and edit it and display its content using the Help menu action? Any help would be appreciated. Thanks in advance.
The way to add a dialog to your project depends a little bit on what development environment you are using. You can always use QtDesigner (part of Qt) to design your About dialog and then add it to your project. To display it, just call the exec() function of the QDialog class in a slot connected to the triggered() signal of your About QAction object.
I would like to know what the established procedure is for initializing the controls within a Qt custom dialog box. In the code I am writing, the dialog would present a QListView containing directories from an object passed (by reference) to the dialog class during construction. When the dialog is displayed, I obviously want the list to display the directories currently configured in the object.
Where should this be done though? Perhaps in the overridden showEvent() method?
Background: I used to do a lot of MFC programming back in the day, and would have done this sort of stuff in the OnCreate method, or some such, once the window object had been created.
Thankfully Qt doesn't require you to do any hooking to find the moment to create things (unless you want to). If you look over the Qt examples for dialogs, most do all the constructing in the constructor:
http://doc.qt.io/archives/qt-4.7/examples-dialogs.html
The tab dialog example--for instance--doesn't do "on-demand" initializing of tabs. Although you could wire something up via the currentChanged signal:
http://doc.qt.io/archives/qt-4.7/qtabwidget.html#currentChanged
Wizard-style dialogs have initializePage and cleanupPage methods:
http://doc.qt.io/archives/qt-4.7/qwizardpage.html#initializePage
http://doc.qt.io/archives/qt-4.7/qwizardpage.html#cleanupPage
But by and large, you can just use the constructor. I guess the main exception would be if find yourself allocating the dialog at a much earlier time from when you actually display it (via exec), and you don't want to bear the performance burden for some part of that until it's actually shown. Such cases should be rare and probably the easiest thing to do is just add your own function that you call (like finalizeCreationBeforeExec).
I am trying to use QSystemTrayIcon for my application and i am facing some problems.
It is the first time i use qt so i am not really used to it.
I followed this tutorial to make a system tray icon but i fail to customize it.
I want to have a button show/hide and not 3 show, hide, restore. These actions are really confusing for a newbie and i dont know what to do and what to connect.
I tried some things but with no luck.
Also when the system tray menu appears if you click somewhere else, the menu stays open.
Any way to solve this thing too?
If you want to remove one of the menu items, modify the createTrayIcon function so that it only adds the actions you need (and clean up the unused members once you get it to work). It's that simple.
If you want a single menu item or button to toggle between visible and hidden, you'll need to create a custom slot that calls show() or hide() (or setVisible(bool)) depending on whether the widget is hidden or not (use isVisible() for that for example). Then connect your action to that slot.
Read the Signals and Slots documentation and examples for information about how to create a new slot.
I would like to know the correct way to close an AIR application programmatically.
In my Spark WindowedApplication I have:
this.addEventListener( Event.CLOSING, shutdownApp );
and of course an implementation of the shutdownApp method (which basically tidies up temporary files).
This works fine for the top-right close button of the window. However I also have functionality which needs to shutdown the application. Within the code I have called:
NativeApplication.nativeApplication.exit();
However this doesn't trigger the Event.CLOSING method, and so my temporary files are not cleared up. Should I not be calling nativeApplication.exit ? If so, what should I call instead? I'd rather not have to call my shutdownApp method before the NativeApplication.exit() as this doesn't feel quite so elegant.
Can anyone shed any light on the correct way of doing this?
Thanks,
Phil
I know this question has been answered and accepted, but thought I'd share, I use.
stage.nativeWindow.close();
The documentation looks a bit ambiguous on this and I would have the same interpretation that you did. Did you try the close or exit methods on the WindowedApplication?
Something like this, with FlexGlobals and topLevelApplication:
(FlexGlobals.topLevelApplication as WindowedApplication).close();
or
(FlexGlobals.topLevelApplication as WindowedApplication).exit();
Just give an answer here because I searched for a related question and was not able to find sth.
I wanted to do something similar and close an AIR application when the native close button of the document window (spark.components.Window) is pressed thought that the spark WindowedApplication container (the applications main window) is still active to hold and manage the native menu (at application startup it is also used to display a splash screen. It has to stay open since if it is closed the native menu won't show up or be accessible anymore so its visible property is just set to false).
My main problem was the window closing event. Registering it with ActionScript like
this.addEventListener(Event.Closing, windowClosed);
does not work: No closing event was dispatched.
The only way was to register an event handler directly in the s:Window element at start of the MXML file. I just throw in the closing attribute:
closing="window1_closingHandler(event)"
The event was dispatched then and in window1_closingHandler-function I called
NativeApplication.nativeApplication.exit();
That works for me and shuts down the whole application.
I've created a new dialog using Qt Creator (version 4.7.0) - one of the templated forms (with an OK and a Cancel button).
I want the user to enter some data on the form and then when they click OK, it saves that information. So I had a look, and saw that when the OK button is clicked, it sends and signal to the dialog's accept slot.
So I right clicked on the dialog in the design view, and selected "Go to slot...". I clicked on the "accepted" option, which dropped an on_Dialog_accepted() method into the dialogs class. However, when I run the program and open the dialog, I get an error in my console saying QMetaObject::connectSlotsByName: No matching signal for on_Dialog_accepted()
So what did I do wrong?
I've found documentation on the connectSlotsByName - but nothing about any obvious pratfalls that an inexperienced Qt-developer can get themselves into.
Right-clicking on the dialog in the design view prior to selecting "Go to slot..." made a connection from the dialog's signals to the dialog's slot, which doesn't work with QMetaObject::connectSlotsByName(), since that method searches for all child objects, but not for the object itself.
What you wanted to do actually is right-clicking on the OK button, then selecting "Go to slot..." from there. It will then create a slot with the name of your button widget, and the connection will be made correctly at run-time.
It makes no sense that QtDesigner lets you select "Go to slot..." from the Dialog. You might want to file a bug to Qt's devs for that.
It is basically just as Fred explained: you did not do anything wrong. This is a QtCreator bug. And a pretty old one for that matter. Unfortunately, even two years later nothing in that regard has changed.
The assignee of the aforementioned bug decided to sort of redirect it to this QtCore bug, which simply asks for QMetaObject::connectSlotsByName() to be changed in a way that it also processes the passed object and not only its children (thereby fixing the QtCreator issue).
I had a look at the source and submitted a trivial patch.
Update: The patch got accepted, meaning this bug is going to be fixed in Qt 5.1. Note: it is not relevant which version of QtCreator your are using but which version of Qt you link your code to.