textScaleFactor property
      
      double
      get
      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.
Implementation
double get textScaleFactor => _textPainter.textScaleFactor;
      
      set
      textScaleFactor
      (double value) 
      
    
    
    
Implementation
set textScaleFactor(double value) {
  if (_textPainter.textScaleFactor == value) return;
  _textPainter.textScaleFactor = value;
  _overflowShader = null;
}