QDialog::exec() blocks the application

Question

I currently have a formA that requests input from a user using another form that inherits from QDialog. The form is prompted using QDialog::exec. Now the problem is that there are going to be multiple instances of formA thus whenever any of formA opens up another form as a dialog the entire application blocks.Currently I have something like this

if(formUserInputRequired->exec()==1) //Block until the user selects from a form
{
}

Is there a way to make QDialog::exec not block the entire application I just want it to block only the instance of the form it was called on or something like that but definitely not the entire application?

Update: I do not need a blocking window. However I would like for a way to know when the user is done with the input in another form so that the original form can process that data

@ratchetfreak it is possible: http://stackoverflow.com/questions/9777911/how-do-i-create-a-window-in-different-qt-threads however not trivial, so I deleted my comment — sara, Sep 12 '13 at 15:25

score 8 · Accepted Answer · answered Sep 12 '13 at 15:22

Call the setWindowModality method on the dialog with Qt::WindowModal as the argument.

Qt::NonModal          0  The window is not modal and does not block input to other windows.
Qt::WindowModal       1  The window is modal to a single window hierarchy and blocks input to its parent window, all grandparent windows, and all siblings of its parent and grandparent windows.
Qt::ApplicationModal  2  The window is modal to the application and blocks input to all windows.

Source

score 2 · Answer 2 · answered Sep 12 '13 at 15:55

2

You can use show() instead, and then to grab dialog result you connect the signal of accept to a slot of your formA to treat it, just like:

connect(formUserInputRequired, SIGNAL(accept()), this, SLOT(acceptClicked());
formUserInputRequired->show();

answered Sep 12 '13 at 15:55

ismaelrs

102
4

One closing bracket is missing in the `connect` – ans Jun 29 '21 at 08:25

score 1 · Answer 3 · answered Sep 12 '13 at 15:22

1

set the modality of the dialog to Qt::WindowModal (the default of QDialog is Qt::ApplicationModal)

answered Sep 12 '13 at 15:22

ratchet freak

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score 0 · Answer 4 · answered Sep 12 '13 at 15:29

0

You can use show() method instead of exec(), because exec method has it's own event loop.

answered Sep 12 '13 at 15:29

Dmitry Sazonov

8,801
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QDialog::exec() blocks the application

4 Answers4