Access To QWidget declared in addTab() function.

HenkCoder

Hello guys,
I'm trying to create a simple notepad with tabs but I have a problem.
I made a button to create a new Tab and put this code:

ui->tabWidget->addTab(new QTextEdit(), QString("Tab " + QString::number(ui->tabWidget->count() + 1)));

My question is, there is a way yo access the QTextEdit I declared in the addTab() function?

SGaist

Hi,

QTabWidget::widget is one way.

mrjj

Hi
Do note that QTabWidget::widget returns the QTextEdit as a QWidget pointer so you need to use
qobject_cast to make it a QTextEdit pointer and hence be able to use QTextEdit methods.

HenkCoder

@mrjj
Hi, thank you for answering.
How do I apply this? Sorry I'm new to this framework

mrjj

@HenkCoder
Hi np. its like

QTextEdit * edit = qobject_cast <QTextEdit*> ( ui->tabWidget->widget(0)) ;

if (edit) { // check is important as if its not a QTextEdit then edit is null and app crash :)
edit->xxxxx();
}

SGaist

More information in the function documentation.

HenkCoder

@mrjj
Hey, what does that It statement do? And what do I have to write instead of xxxxx() or is it what I actually have to write?

mrjj

Hi

Hey, what does that It statement do? And what do I have to write instead of xxxxx()?

Hi. this statement takes a base pointer (QWidget *) and cast it to the concrete child type.
In this case a QTextEdit.
This only works it IS a QTextEdit there.
So basically we do like

SomeClass * ptr = ( Otherclass *) ui->tabWidget->widget(0)
but in a saer manner that will fial its its not a QTextWidget.
A pure cast /old type cast will always work but crash the app if
it really not is a TextEdit

edit->xxxxx(); is just to show to call functions in it. xxxx is just like any function it has.

like
edit->toPlainText():

to get all text into QString or what ever you want to do with your textedit

HenkCoder

@mrjj
Ok thanks, but I have two more question.

Can declared that QTextEdit as a global pointer?
what does the '0' mean in ui->tabWidget->widget(0)?
That's it, no more question, thank you for your patience and sorry because I'm new!

SGaist

no there's no need for a global variable, you can use a member variable but do not start using globals for that.
it's explained in the method documentation. It's the index of the widget you want to get.

HenkCoder

@SGaist
Oh ok, but I need it as a global, can I declare it like that?
Thank you for explaining me the widget(0) thing!

mrjj

@HenkCoder
Hi
Why would you need it as a global ?

If you plan something like NotePad++ with tabs then each tab will be its own QTextEdit
and you need to take the right one, depending on which tab user clicks.

So you should hook up a slot to the signal
https://doc.qt.io/qt-5/qtabwidget.html#currentChanged
and there you got the index (the parameter) to use to ask for the widget, then
convert it and you can alter text or what you want.

HenkCoder

@mrjj
Hey, I need it as a global because I want to put other buttons like bold, italics, underline etc, but I cannot access the QTextEdit if it's not a global

mrjj

@HenkCoder

Hi
You still dont need a global variable for that :)

Any button that must access the TextEdit can just get it.

like you cna make a helper function to make this easy

TextEdit * MainWindow::GetEditor() {
  return q_objectcast<TextEdit *> ( ui->tabWidget->currentWidget() );
}

then in BOLd button clicked etc , you can do
void BoldClicked() {
TextEdit * edit = GetEditor();  to have access to the current tab as a TextEdit
if (edit) {
make text bold ...
}

}

HenkCoder

@mrjj
Oooh, I understand.
Thank you all for the help!