Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: GradientText(
          text: [
            GradientTextData(
              text: "abcdefg",
              gradient: LinearGradient(
                colors: [const Color(0xFF70EAAF), const Color(0xFF2A9963)],
                begin: AlignmentDirectional.centerStart,
                end: AlignmentDirectional.centerEnd,
              ),
              style: TextStyle(
                color: Colors.white,
                fontSize: 21,
                fontWeight: FontWeight.w600,
                overflow: TextOverflow.ellipsis,
              ),
            )
          ],
        ),
      )
    );
  }

class GradientText extends StatelessWidget {
  const GradientText({
    required this.text,
    this.maxLines,
    this.ellipsis,
    super.key,
  });

  final List<GradientTextData> text;
  final int? maxLines;
  final String? ellipsis;

  @override
  Widget build(BuildContext context) {
    final TextPainter textPainter = _GradientTextPainter.createTextPainter(
      text,
      maxLines: maxLines,
      ellipsis: ellipsis,
    );
    textPainter.layout();

    return CustomPaint(
      size: textPainter.size,
      painter: _GradientTextPainter(
        text: text,
        maxLines: maxLines,
        ellipsis: ellipsis,
      ),
    );
  }
}

@immutable
class GradientTextData {
  const GradientTextData({
    required this.text,
    required this.gradient,
    required this.style,
  });

  final String text;
  final Gradient gradient;
  final TextStyle style;
}

class _GradientTextPainter extends CustomPainter {
  _GradientTextPainter({
    required this.text,
    this.maxLines,
    this.ellipsis,
  });

  final List<GradientTextData> text;
  final int? maxLines;
  final String? ellipsis;

  static TextPainter createTextPainter(
    List<GradientTextData> text, {
    Size? gradientSize,
    int? maxLines,
    String? ellipsis,
  }) {
    return TextPainter(
      maxLines: maxLines,
      ellipsis: ellipsis,
      text: TextSpan(
        children: text.map((e) {
          TextStyle textStyle = e.style;
          if (gradientSize != null) {
            final Paint gradientPaint = new Paint()
              ..shader = e.gradient.createShader(
                new Rect.fromLTWH(0.0, 0.0, gradientSize.width, gradientSize.height),
                textDirection: TextDirection.ltr,
              );
            textStyle = textStyle.copyWith(foreground: gradientPaint);
          }

          return TextSpan(
            text: e.text,
            style: textStyle,
          );
        }).toList(),
      ),
      textDirection: TextDirection.ltr,
    );
  }

  @override
  void paint(Canvas canvas, Size size) {
    TextPainter textPainter = createTextPainter(
      text,
      gradientSize: size,
      maxLines: maxLines,
      ellipsis: ellipsis,
    );
    textPainter.layout(minWidth: 0, maxWidth: size.width,);
    textPainter.paint(canvas, Offset.zero);
  }

  @override
  bool shouldRepaint(_GradientTextPainter oldDelegate) {
    return text != oldDelegate.text;
  }
}