Gradient.radial() from the documentation isn't available? - dart

Question

I want to create a gradient shader.
The Gradient.radial() constructor should return one.
However, VS Code claims that this method is not defined for Gradient. huh.
Now, from what I've seen online, you can create a RadialGradient object and then use .createShader(rect) to convert it into a shader (haven't got it work yet, but maybe I'm implementing it wrong), but that can't be the intended way, right?
Update:
As #pskink pointed out, I'm using a newer version of Flutter and have to import the Gradient shader class as part of the Dart ui library.
The resulting code is valid and looks like this:
paint.shader = ui.Gradient.radial(
Offset(-.5, -.5),
1, // The radius
List.from({
Colors.lightBlueAccent,
Colors.blue,
Colors.deepPurpleAccent},
growable: false
)
);
Unfortunately it doesn't render anything.
This is how the code with the .createShader() method on the other Gradient class looks.
RadialGradient _gradient = RadialGradient(
colors: List.from({
Colors.lightBlueAccent,
Colors.blue,
Colors.deepPurpleAccent},
growable: false),
);
// center is the center of the canvas
paint.shader = _gradient.createShader(
Rect.fromCircle(
center: center,
radius: size.shortestSide / 2
)
);
This is kinda ugly IMO (and less efficient?), but it does render the expected result.
2nd Update:
When having more than 2 color elements in the Gradient shader class you can't omit the stops. This info is just being presented as an errorlog, which is why I didn't see it. With that being fixed: Both versions return different results...
This code returns this gradient:
#override
void paint(Canvas canvas, Size size) {
final center = Offset(size.width / 2, size.height / 2);
final paint = Paint();
RadialGradient _gradient = RadialGradient(
radius: 1,
center: Alignment(-.5, -.5),
tileMode: TileMode.clamp,
colors: List.from({Colors.lightBlueAccent, Colors.blue, Colors.deepPurpleAccent}, growable: false),
stops: List.from({0.0, 0.5, 1.0}, growable: false),
);
paint.shader = _gradient.createShader(
Rect.fromCircle(
center: center,
radius: size.shortestSide / 2
)
);
canvas.drawCircle(center, size.shortestSide / 2, paint);
}
While this code renders this gradient:
#override
void paint(Canvas canvas, Size size) {
final center = Offset(size.width / 2, size.height / 2);
final paint = Paint();
paint.shader = ui.Gradient.radial(
Offset(-.5, -.5),
1, // this is the radius
List.from({Colors.lightBlueAccent, Colors.blue, Colors.deepPurpleAccent},
growable: false),
List.from({0.0, 0.5, 1.0}, growable: false),
TileMode.clamp,
);
canvas.drawCircle(center, size.shortestSide / 2, paint);
}