gradient_text.dart

final Shader linearGradient = LinearGradient(
  colors: <Color>[Colors.pink, Colors.green],
).createShader(Rect.fromLTWH(0.0, 0.0, 200.0, 70.0));

Text('Hello Gradients!',
    style: new TextStyle(
    fontSize: 60.0,
    fontWeight: FontWeight.bold,
    foreground: Paint()..shader = linearGradient),
)
  
Shader getTextGradient(RenderBox renderBox) {
  if (renderBox == null) return null;
  return LinearGradient(
    colors: <Color>[Colors.deepOrange, Colors.lightGreenAccent],
  ).createShader(Rect.fromLTWH(
      renderBox.localToGlobal(Offset.zero).dx,
      renderBox.localToGlobal(Offset.zero).dy,
      renderBox.size.width,
      renderBox.size.height));
}