enter image description here

final textSpan = TextSpan(text: text, style: textStyle);
final textPainter =
TextPainter(text: textSpan, textDirection: TextDirection.ltr,maxLines: 1,textAlign: TextAlign.left);

textPainter.layout(minWidth: 0, maxWidth: double.infinity);
var computeLineMetrics = textPainter.computeLineMetrics();
for(var line in computeLineMetrics){
  log("line $line");
}

text_style =TextStyle(inherit: true, color: Color(0xff000000), family: MoliFont, size: 378.0, height: 1.0x)
text = x

green box is the x size but I want to get the red box size
please help me ,thank you !

I want to get the red box size