Why plus 1 when getting the content height of QTextEdit?

[ideaplus]

Why plus 1 when getting the content height of QTextEdit?
c++

QMargins margins = textEdit->contentsMargins();
QSizeF documentSize =  textEdit->document()->size();
int height = documentSize.height() + margins.top() + margins.bottom() + 1;

python

margins = self.textEdit.contentsMargins()
size = self.textEdit.document().size()
height = size.height() + margins.top() + margins.bottom() + 1

https://forum.qt.io/topic/87934/set-exact-height-for-qplaintextedit-according-to-height/3

[SGaist]

Hi,

You have the answer in the same thread you are linking to.

[ideaplus]

@SGaist But I can't find answer. Is my question too vague? I don't know why need plus 1, +1

[SGaist]

Did you read the last post of the thread ? It contains two links: one points to a Qt bug report where the logic is explained and another one that points to the QPlainTextEdit documentation.