make QPlainTextEdit ignore scrolling

[Grand_Titan]

I can't find a solution for this but is there a way to make a QPlainTextEdit ignore all scrolling action like mouse wheel, space bar, clicking on text and dragging down and so on?

[SGaist]

Hi,

You can install an event filter on it and filter out all the unwanted operations. You might have to do that on the widget's scrollbars as well.

[Grand_Titan]

@SGaist Hello I installed an event filter but im not sure how to ignore it or what the event i want to ignore is called i tried a few but none seemed to get recognized
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
if (obj == ui->plainTextDisplay) {
//something else
}
}
if (obj == ui->plainTextLines){
if(event->type() == QEvent::Scroll){
qDebug() << "hi";
event->ignore();
}
}
return QMainWindow::eventFilter(obj, event);
}
Just in case i did something wrong while installing the event filter
ui->plainTextDisplay->setFocus();
ui->plainTextDisplay->installEventFilter(this);
ui->plainTextLines->setFocus();
ui->plainTextLines->installEventFilter(this);
mainwindow.h:
protected:
bool eventFilter(QObject *obj, QEvent *ev) override;

[mpergand]

@Grand_Titan said in make QPlainTextEdit ignore scrolling:

if (obj == ui->plainTextLines){
if(event->type() == QEvent::Scroll){
qDebug() << "hi";
event->ignore();
}

You need to return true to filter the event.

[Grand_Titan]

@mpergand Thanks. But still I can't figure out which event is the one that controlls scrolling and those things.
if(event->type() == QEvent::Scroll || event->type() == QEvent::ScrollPrepare){
qDebug() << "hi";
event->ignore();
return true;
}

[Grand_Titan]

if (obj == ui->plainTextLines){
    if(event->type() == QEvent::Wheel){
        qDebug() << "hi";
        return true;
    }else{
        return false;
    }
}

I tried it with the Wheel event but that event only gets called if i scroll when the text cannot scroll any further. I need to prevent scrolling always..

[mpergand]

Try this:

class Text : public QPlainTextEdit
{
	public:

		Text() : QPlainTextEdit(nullptr)
		{
			appendPlainText("A\nB\nC\nD\nE\nF\nG\nH\nI\nJ");
			installEventFilter(this);
			setTextInteractionFlags(Qt::NoTextInteraction);
		}

	bool eventFilter(QObject *o, QEvent *e)
	{
		qDebug()<<o<<e->type();
		if( (e->type()==QEvent::Wheel) ||
			(e->type()==QEvent::MouseMove) ||
			(e->type()==QEvent::MouseButtonPress) ||
			(e->type()==QEvent::MouseButtonDblClick) )
			return true;

		return QPlainTextEdit::eventFilter(o,e);
	}
};

[Grand_Titan]

@mpergand I cant filter mouseButtonPress and dbclick cuz i still use this elsewhere. but every time i include this in my code: "==QEvent::MouseMove" it crashes on run. Same goes for noTextInteraction i still need to be able to interact with the text that way i just want to prevent scrolling.

[zeljko]

@Grand_Titan try to catch viewport events and block scrolling.

[Grand_Titan]

I forgot to close this since I already fixed the issue even though it was a bit of a dirty fix. I just did:
"connect(ui->plainTextLines->verticalScrollBar(), &QScrollBar::valueChanged, this, &MainWindow::handleLinesScroll);"
and in the handleLinesScroll I just set the scroll bar to the value it was before. But it works flawlessly and I see no performance impact.