How to set number of lines for an QTextEdit?

Question

I use a QTextEdit for some inputs. But I want to adjust the height of the box. Can I set the height based on the number of lines I want to have visible at a time?

Answer 1

This should work:

QTextEdit *myEdit = new QTextEdit(myContentString);
QSize myEditSize = myEdit->document()->size().toSize();
myEditSize.setWidth(QWIDGETSIZE_MAX);
myEdit->setMaximumSize(myEditSize);

Answer 2

If you use QPlainTextEdit, something like this should do the trick:

void SetHeight (QPlainTextEdit* edit, int nRows)
  {
  QFontMetrics m (edit -> font()) ;
  int RowHeight = m.lineSpacing() ;
  edit -> setFixedHeight  (nRows * RowHeight) ;
  }

You might want to add two or three pixels as margin; experiment will tell.

Answer 3

Use QFont to determine the height of a single line of text in the QTextEdit (QTextEdit should have a font property). After that multiply the QFont's height value with the number of lines you want to show and set the widget's (minimum-)height to that value.

Answer 4

Improving the accepted answer about QPlainTextEdit. In addition to lineSpacing, value for setFixedHeight should contain: 2 margins of the underlying QTextDocument, 2 widths of the frame and widget's contents margins. Besides that, QFontMetrics must be got from a font of the document, not of the widget itself. So, hypothetical function setHeight should read as follows:

void setHeight (QPlainTextEdit *ptxt, int nRows)
{
    QTextDocument *pdoc = ptxt->document ();
    QFontMetrics fm (pdoc->defaultFont ());
    QMargins margins = ptxt->contentsMargins ();
    int nHeight = fm.lineSpacing () * nRows +
        (pdoc->documentMargin () + ptxt->frameWidth ()) * 2 +
        margins.top () + margins.bottom ();
    ptxt->setFixedHeight (nHeight);
}

Answer 5

QTextEdit is a normal widget, so you can use minimumHeight property. I believe, however, that it is really impossible to set minimum height based on number of lines. This would resize automagically the minimum size of a widget every time you change size of the font. But if you know the size of the font, you can set some usable minimum size of your widget.