Answers for "custompaint flutter"

flutter CustomPaint clip

ClipRRect(
  borderRadius: BorderRadius.only(
    topLeft: Radius.circular(25.0),
    topRight: Radius.circular(25.0),
    bottomRight: Radius.circular(25.0),
  ),
  child: CustomPaint(
          painter: (...),
          child: (...),
        ),
)

why does custom paint class has a child in flutter

CustomPaint(
  painter: Sky(),
  child: Center(
    child: Text(
      'Once upon a time...',
      style: const TextStyle(
        fontSize: 40.0,
        fontWeight: FontWeight.w900,
        color: Color(0xFFFFFFFF),
      ),
    ),
  ),
)

flutter custompaint

// FOR PAINTING LINES
class ShapePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    var paint = Paint()
      ..color = Colors.teal
      ..strokeWidth = 5
      ..strokeCap = StrokeCap.round;

    Offset startingPoint = Offset(0, size.height / 2);
    Offset endingPoint = Offset(size.width, size.height / 2);

    canvas.drawLine(startingPoint, endingPoint, paint);
  }

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

// FOR PAINTING LINES
class ShapePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    var paint = Paint()
      ..color = Colors.teal
      ..strokeWidth = 5
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round;

    var path = Path();
    path.moveTo(0, size.height / 2);
    path.lineTo(size.width, size.height / 2);
    canvas.drawPath(path, paint);
  }

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

// FOR PAINTING CIRCLES
class ShapePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    var paint = Paint()
      ..color = Colors.teal
      ..strokeWidth = 5
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round;

    Offset center = Offset(size.width / 2, size.height / 2);

    canvas.drawCircle(center, 100, paint);
  }

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

// FOR PAINTING CIRCLES
class ShapePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    var paint = Paint()
      ..color = Colors.teal
      ..strokeWidth = 5
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round;

    var path = Path();
    path.addOval(Rect.fromCircle(
      center: Offset(size.width / 2, size.height / 2),
      radius: 100,
    ));
    canvas.drawPath(path, paint);
  }

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


// Practical Usases
Expanded(
  child: CustomPaint(
    painter: ShapePainter(_sides, _radius, _radians),
    child: Container(),
  ),
),

// Class Draw
// FOR PAINTING POLYGONS
class ShapePainter extends CustomPainter {
  final double sides;
  final double radius;
  final double radians;
  ShapePainter(this.sides, this.radius, this.radians);

  @override
  void paint(Canvas canvas, Size size) {
    var paint = Paint()
      ..color = Colors.teal
      ..strokeWidth = 5
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round;

    var path = Path();

    var angle = (math.pi * 2) / sides;

    Offset center = Offset(size.width / 2, size.height / 2);
    Offset startPoint =
        Offset(radius * math.cos(radians), radius * math.sin(radians));

    path.moveTo(startPoint.dx + center.dx, startPoint.dy + center.dy);

    for (int i = 1; i <= sides; i++) {
      double x = radius * math.cos(radians + angle * i) + center.dx;
      double y = radius * math.sin(radians + angle * i) + center.dy;
      path.lineTo(x, y);
    }
    path.close();
    canvas.drawPath(path, paint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}