calculateRowHeight static method
you can use this helper function to calculate / measure the height of a text with a given width (e.g. = colWidth) and fontSize but be aware, that the performance of this function is not really good because it has to measure the text and this is a quite complicated thing...
Implementation
static double calculateRowHeight(String text, double width, double fontSize) {
final style = TextStyle(fontSize: fontSize);
TextPainter textPainter = TextPainter()
..text = TextSpan(text: text, style: style)
..textDirection = TextDirection.ltr
..layout(minWidth: 0, maxWidth: width);
var height = textPainter.height;
textPainter.dispose();
return height;
}