How do I rotate something 15 degrees in Flutter?

Question

The Flutter docs show an example of rotating a \"div\" by 15 degrees, both for HTML/CSS and Flutter code:

The Flutter code is:

var container = new Contai         


        

Answer 1

You can use Transform.rotate to rotate your widget. I used Text and rotated it with 45˚ (π/4)

Example:

import 'dart:math' as math;

Transform.rotate(
  angle: -math.pi / 4,
  child: Text('Text'),
)

Answer 2

In mobile apps, I think it's kind of rare to have things start out rotated 15 degrees and just stay there forever. So that may be why Flutter's support for rotation is better if you're planning to adjust the rotation over time.

It feels like overkill, but a RotationTransition with an AlwaysStoppedAnimation would accomplish exactly what you want.

new RotationTransition(
  turns: new AlwaysStoppedAnimation(15 / 360),
  child: new Text("Lorem ipsum"),
)

If you want to rotate something 90, 180, or 270 degrees, you can use a RotatedBox.

new RotatedBox(
  quarterTurns: 1,
  child: new Text("Lorem ipsum")
)

Answer 3

If you are working with a canvas (as in a CustomPaint widget), you can rotate 15 degrees like this:

import 'dart:math' as math;

class MyPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    canvas.save();

    // rotate the canvas
    final degrees = 15;
    final radians = degrees * math.pi / 180;
    canvas.rotate(radians);

    // draw the text
    final textStyle = TextStyle(color: Colors.black, fontSize: 30);
    final textSpan = TextSpan(text: 'Hello, world.', style: textStyle);
    TextPainter(text: textSpan, textDirection: TextDirection.ltr)
      ..layout(minWidth: 0, maxWidth: size.width)
      ..paint(canvas, Offset(0, 0));

    canvas.restore();
  }

  @override
  bool shouldRepaint(CustomPainter old) {
    return false;
  }
}

However, if you are doing something simple then I would use a RotatedBox or Transform.rotate as suggested by the other answers.