Hey,

I'm trying to catch the users input in a QTextEdit and check for illegal characters.

I catch the signal "textChanged()" and check the input (edit->toPlainText()) for illegal characters.

If some illegal characters are found, I replace or remove them and set the new text (edit->setPlainText(QString)).

Now my problem is the cursor position. I found out that calling QTextEdit::setPlainText(QString) sets a new QTextCursor at position '0'.

I manage this by saving the QTextCursor's recent position (before changing input) and set this position to the new QTextCursor, like this:
Qt Code: 
  1. this->blockSignals(true);
  2.   QString input = this->toPlainText();
  3.  
  4.   // ... some checks and replaces with input
  5.  
  6.   QTextCursor cursor = this->textCursor();
  7.   int cursorPos = this->textCursor().position();
  8.  
  9.   this->setPlainText(input); // this deletes the previous cursor
  10.  
  11.   cursor.setPosition(cursorPos);
  12.   this->setTextCursor(cursor);
  13.  
  14.   this->blockSignals(false);
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This works great. What I don't under stand is, why the following code (exactly the same commands, only different order) doesn't work:
Qt Code: 
  1. this->blockSignals(true);
  2.   QString input = this->toPlainText();
  3.  
  4.   // ... some checks and replaces with input
  5.  
  6.   QTextCursor cursor = this->textCursor();
  7.   int cursorPos = this->textCursor().position();
  8.   cursor.setPosition(cursorPos);
  9.  
  10.   this->setPlainText(input); // this deletes the previous cursor
  11.  
  12.   this->setTextCursor(cursor);
  13.  
  14.   this->blockSignals(false);
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I would understand that if "cursor" was a pointer, but it isn't!! How can QTextEdit recognize that I set the new cursor position before setting new text?

I would really appreciate a good explanation of this strange behaviour...

Thank you in anticipation!
Binary