textScaleFactor property

double textScaleFactor

The number of font pixels for each logical pixel.

For example, if the text scale factor is 1.5, text will be 50% larger than the specified font size.

After this is set, you must call layout before the next call to paint.

Implementation 

double get textScaleFactor => _textScaleFactor;
void textScaleFactor= (double value)

Implementation 

set textScaleFactor(double value) {
  assert(value != null);
  if (_textScaleFactor == value)
    return;
  _textScaleFactor = value;
  _paragraph = null;
  _layoutTemplate = null;
  _needsLayout = true;
}