measureText static method
计算文本尺寸
Implementation
static Size measureText(String text, TextStyle style,
{double maxWidth = double.infinity}) {
final TextPainter textPainter = TextPainter(
text: TextSpan(text: text, style: style),
maxLines: 1,
textDirection: TextDirection.ltr,
);
textPainter.layout(maxWidth: maxWidth);
return textPainter.size;
}