Problem with QPlainTextEdit

[GGG03]

I need to show data like a terminal in QT (Like Arduino with a Serial port). I'm using a QPlainTextEdit because it is the only option I've found. But it adds so much latency and makes the app laggy.

Here is with QTextEdit.

Here without it.
Is there anyway to make it not laggy or to show data like arduino's serial monitor?

[GGG03]

I found the problem. It was the font. I was using Terminal 9, and with Segou UI it is not laggy.

[CPPUIX]

@GGG03 Would this be of any help?

Or any of these?

If not and you still want to continue using QPlainTextEdit, then you need to show how you are using it, maybe someone can optimize your code and improve its performance.

[GGG03]

This is the code of the QTextEdit

    cursor.movePosition(QTextCursor::Start);
    cursor.insertText(show);
    nLines += 2;

    if (nLines < -100)
    {
        nLines -= 2;
        cursor.movePosition(QTextCursor::Start);
        cursor.movePosition(QTextCursor::Down, QTextCursor::MoveAnchor, nLines-1);
        cursor.select(QTextCursor::LineUnderCursor);
        cursor.removeSelectedText();
        cursor.movePosition(QTextCursor::Down, QTextCursor::MoveAnchor, 1);
        cursor.select(QTextCursor::LineUnderCursor);
        cursor.removeSelectedText();
        cursor.deleteChar();
    }

[JonB]

@GGG03
That is quite a bit of moving the cursor around, selecting, scrolling etc. It might be the case that reading the whole text from the text edit (or keeping it in memory), deleting the first line in memory from it, appending the new stuff and doing a complete setText() could be faster, you'd have to try. Or, I can't figure how often you are updating, you might want to "buffer" a few updates at a time. For example, user cannot read text updated e.g. every 1ms so no need to.

[GGG03]

@JonB I'm gonna test it with setText. Just so you know, I have the same problem deactivating the erase part, so I don't think is the cursor.

[GGG03]

@JonB Nothing, it works even worse.

[GGG03]

I found the problem. It was the font. I was using Terminal 9, and with Segou UI it is not laggy.

[CPPUIX]

@GGG03 don't forget to mark this topic as solved if your problem's solved.

[JonB]

@GGG03 said in Problem with QPlainTextEdit:

I found the problem. It was the font. I was using Terminal 9, and with Segou UI it is not laggy.

LOL! Hopeless.