In my code I do have to do manually:
/*This works but there must be a better way*/
listView->hide();//INSTEAD OF THIS I'D RATHER SEND A SIGNAL CAUSING
LISTVIEW TO UPDATE -
update(), viewport()->update, repaint() doesn't work,
Basically I have a listView in which I'm displaying selection of files. After pressing ok this dialog closes. When I open this dialog again and pick another set of files the old ones are shown, and I have to hide and show listView in order to see newly selected files.
What you need is the clearSelection slot. Connect it to the finished signal of your dialog.
Related
I have a settings dialog that has some settings that require another dialog to fully configure. My window shows a preview of the data as it's being tweaked by these settings. Upon clicking on the configuration button I launch another modal dialog with some knobs to twist to fine tune the particular setting.
I wish to send the result of the twisting of the knobs on the child dialog back to the parent dialog so that it can show the new preview data as the knobs on the child are being played with. The way I imagine it is I have a "refresh preview" function in the parent that is called after modification of it's data preview member variables. The question is, how do I do this? How can I access getters/setters from the parent dialog as a modal child dialog? If I do access them will the preview change or will it be blocked because of the modality of the child?
Thank you!
In Qt world, it is generally encouraged to exploit the Signal/Slot mechanism. In short, classes can send signals when something changes within that class. And slots can receive such signals provided we notified the receiving classes appropriately.
Let us look at how we can do it for our present case.
In our settings dialog constructor, we include this code (assumption is that you display the "another" dialog when a button is pressed):
Dialog *dialog = new Dialog();
connect(dialog->dial(), &QDial::valueChanged, this, &QSettingsDialog::changeTemp);
Code walkthrough:
Our QDialog has been constructed with a QDial object, dial. We access that member pointer with dialog->dial().
We tie the signal that emits the value changed on the dial to the slot called changeTemp that receives the value changed and sets the display widget on the settings dialog (parent) accordingly.
The changeTemp method might be like so:
void QSettingsDialog::changeTemp(int val)
{
lineEdit->setText(QString::number(val));
}
Notes:
You need to declare the Q_OBJECT macro on all classes that need to implement Signals and slot. In this case, both the settings dialog and the child dialog.
The above signal/slot signature is the new Qt5 signature. If you are on a version below 5.0, the signature is different. Refer to the docs.
I have a modeless QDialog box that popup on errors/warning in my Qt application, I want to force the user to only focus on that dialog box and not click anything in the application until they clicked Ok on the dialog box.
I need the dialog box to remain modeless. A solution like hiding the main window or covering it up is not acceptable.
At the moment I'm using setModal(true); to solve my problem. But I think this method might be stopping the main application from executing.
From the documentation:
If you use show() and setModal(true) together to perform a long
operation, you must call QApplication::processEvents() periodically
during processing to enable the user to interact with the dialog.
Instead of using a QDialog box, try using qDebug statements in your code or a log file using qInstallMsgHandler.
You could also show a QTextEdit and post your log/error messages there in real time, too.
http://qt-project.org/doc/qt-4.8/debug.html
http://qt-project.org/doc/qt-4.8/qdebug.html#details
http://qt-project.org/doc/qt-4.8/qtglobal.html#qInstallMsgHandler
http://qt-project.org/doc/qt-4.8/qtextedit.html#details
If you still really want to debug using a QDialog box for errors, in a pseudo modal dialog but not modal dialog, you could try using eventFilters to prevent mouse and keyboard events from arriving at any other window, but it would be tricky to allow the exception to end up only at QDialog, but it is do-able.
You could also go to the one or two widgets that accept mouse and keyboard input, and ignore the input if the a QDialogBox is visible. But both of these ways of showing an error, but limiting input without making it Modal is really hacky, and would probably be error prone.
I have 3 buttons on QMessageBox added by QMessageBox::addButton() method. Is it possible to prevent closing the message box if a button has been clicked? By default every button closes the window, but I don't want to do it for one button.
One interesting way to approach it that worked for me is to completely disconnect the signals for the target button created, and then re-add the intended functionality. This won't work for everyone, especially if the button isn't created this way and/or you still want to close the dialog correctly. (There might be a way to add it back and/or simulate the behavior with QDialog::accept, QDialog::reject, QDialog::done - haven't tried yet.)
Example:
QMessageBox *msgBox = new QMessageBox(this);
QAbstractButton *doNotCloseButton = msgBox->addButton(tr("This button will not close anything"), QMessageBox::ActionRole);
// Disconnect all events - this will prevent the button from closing the dialog
doNotCloseButton->disconnect();
connect(doNotCloseButton, &QAbstractButton::clicked, this, [=](){ doNotCloseButton->setText("See? Still open!"); });
If you can get a pointer to the QMessageBox widget, you can try to install a QObject::eventFilter on it which filters the QEvent::Close.
Just had the same problem but I wanted to add a checkbox and it kept closing the dialog on clicked even with the ButtonRole set to QMessageBox::ActionRole (tried others too). For this scenario I just called blockSignals(true) on the QCheckBox and now it allows check/uncheck behaviour without closing the dialog. Luckily QCheckBox works fine without signals but assume you want a signal from your button.
They should likely add a new role that doesn't close the dialog as it's a pain to derive a class for simple customizations.
I looked through the addButton() functions overloads, but there is no custom behavior for the buttons you add with this method. They will behave like the standard buttons on a messagebox should.
However if you want to create a fully customizable dialog, then your best option is to extend the QDialog class and use whatever controlls you like on it.
Thanks to #Albert's Answer, I found that this also possible in python:
messagebox = QMessageBox()
button = QPushButton("This button will not close anything")
messagebox.addButton(button, QMessageBox.ButtonRole.NoRole)
button.disconnect()
I am developing a project using Qt4 and I have run into a slight issue.
I am creating a modal window from the main window. I want this to disable the toolbar at the top.
I have a menu item that spawns the modal from the menu. What I want is that when the modal is spawned that menus is disabled. I have tried using the setEnabled(false) function but that doesn't reset it.
Here is the code:
void Main_Screen::Create_ViPro()
{
std::auto_ptr<ViPro_Dialog> modal(new ViPro_Dialog(this));
modal->show();
modal->exec();
}
So It is just a simple class that is triggered when a menu item is selected. I feel that the problem stems from the fact that i'm setting the parent to the main screen, however I don't know how to create a modal without a parent(it doesn't make sense to do that). Is there a way to disable the parents toolbar from the child? The only thing I have seen so far is _fileMenu->setEnabled(false);
That works as long as I don't create the modal, but as soon as that is spawned, the menu works again. I'm totally lost.
Thanks in advance
Edit as Patrice
Here is the constructor
Main_Screen::Main_Screen(QWidget* parent /*= NULL*/)
: QMainWindow(parent),
_newProj(new QAction(tr("New &ViPro"), this)),
_fileMenu(menuBar()->addMenu(tr("&File")))
{
//create slot for creating a new project
connect(_newProj.get(), SIGNAL(triggered()), this, SLOT(Create_ViPro()));
_fileMenu->addAction(_newProj.get());
//if i do this then setEnabled(false) works perfectly and i can't access the menu
Create_ViPro()
}
So the function is signaled by triggering the newproject action. If i call the function directly from within the constructor it disables it as you stated patrice, however, if I have the function called via the trigger, it doesn't disable it. Am I handling the signal / slot mechanism wrong? Thanks again.
Another example, if I make the function create_vipro() as below
void Main_Screen::Create_ViPro()
{
_fileMenu->setEnabled(false);
}
The file menu isn't disabled when I trigger the event, so it must have nothing to do with the modal itself, but instead how signals are handled.
Since child is a modal dialog main screen can't react to event. But you can disable the toolbar (or menubar) before creating the modal dialog and enable it as soon as you leave the exec function:
void Main_Screen::Create_ViPro()
{
_fileMenu->setEnabled(false);
std::auto_ptr<ViPro_Dialog> modal(new ViPro_Dialog(this));
modal->show();
modal->exec(); // Will stay here until you close the modal dialog
_fileMenu->setEnabled(true);
}
if ViPro_Dialog is really a modal dialog it will works.
Another thing, since ViPro_Dialog is modal you can declare it locally without using auto_ptr:
void Main_Screen::Create_ViPro()
{
_fileMenu->setEnabled(false);
ViPro_Dialog modal(this);
modal.show();
modal.exec(); // Will stay here until you close the modal dialog
_fileMenu->setEnabled(true);
}
EDIT:
I guess (I can't test at work) that you can't enable/disable menu when it is executing a QAction. Signal is calling slots sequentially so QAction is busy when you try to disable the menu.
Try this:
In Main Screen, create a slot with one boolean parameter that enable/disable menubar. Just call the setEnabled function
In ViPro_Dialog, emit a signal with a boolean parameter (false at startup, true at validation)
In Create_ViPro, once dialog created, connect the new signal with the slot, exec dialog and don't forget to disconnect slot from signal:
void Main_Screen::Create_ViPro()
{
ViPro_Dialog modal(this);
// Connect signal/slot
modal.show();
modal.exec(); // Will stay here until you close the modal dialog
// Disconnect signal/slot
}
This can achieve what you want
EDIT2
You are doing a mistake when using modal dialog. There's a conflict between show() and exec(). When you are displaying modal dialog you don't need to disable other windows: it's automatically done by modal status of the dialog. There are many modal depth: http://qt-project.org/doc/qt-4.8/qt.html#WindowModality-enum. So your code should be:
void Main_Screen::Create_ViPro()
{
ViPro_Dialog modal(this);
// modal.setWindowModality(Qt::WindowModal); // Uncomment this line if you want to only disable parent
modal.exec();
}
Read this for more detail: http://qt-project.org/doc/qt-4.8/QDialog.html#details.
Using exec() doesn't just create a modal dialog, it also suspends most of the regular event handling, and only handles events in the dialog that is in exec(). This may include some UI updates (like the transitions from enabled to disabled), but I'm not positive. A better way to handle this might be to explicitly set the dialog modal, but allow the regular event loop to continue, something like this:
void Main_Screen::Create_ViPro()
{
ViPro_Dialog* modal = new ViPro_Dialog(this);
modal->setModal(true);
modal->show();
}
That code will still not visually disable the toolbar or menubar, but they should be unresponsive. To disable them, you could try combining this with Patrice Bernassola's answer.
In my QMenuBar, I have several menus.
One of those menus has a QWidgetAction in it.
It shows up fine, but the problem is that once the user completes his input, I want the menu to disappear (as is the normal behavior for a classical QAction).
However, I am not sure on how to do that. In my QWidgetAction, there is a button the user presses when he is done; I can therefore bind to this button's clicked() signal.
In the slot, I tried to setFocus() an element outside the menu but the menu still doesn't disappear.
How to tell the menu to close itself when my users finish interacting with the QWidgetAction?
Thanks
QMenu inherits QWidget, so calling yourMenu->hide() should do the work.
Hope this helps.