A Guide to Using ClipPath for Custom Shapes

In this comprehensive guide, we will delve into the world of Flutter's ClipPath and Path widgets. By the end of this article, we will have a clear understanding of how to use the ClipPath widget to draw complex shapes and how the Path widget can be utilized to define the shape that is used to clip the child widget. In this article we will have the following output.

ClipPath is a widget in Flutter that can be used to clip another widget using a custom clipper. A clipper is an object that defines the shape that is used to clip the child widget. In Flutter, the Path widget can be used as a clipper to create complex shapes.

In this article, we'll demonstrate how to use the ClipPath widget with a Path clipper to draw a star shape.

First, let's create a Path that defines the shape of the star. We'll use the moveTo method to set the starting point of the Path, and then we'll use the lineTo method to add several lines that connect to the starting point and form the shape of the star.

Path _starPath() {
  return Path()
    ..moveTo(50.0, 0.0)
    ..lineTo(61.0, 35.0)
    ..lineTo(98.0, 35.0)
    ..lineTo(68.0, 58.0)
    ..lineTo(79.0, 95.0)
    ..lineTo(50.0, 70.0)
    ..lineTo(21.0, 95.0)
    ..lineTo(32.0, 58.0)
    ..lineTo(2.0, 35.0)
    ..lineTo(39.0, 35.0)
    ..close();
}

moveTo property in the Path widget in Flutter is used to set the starting point of the Path. It takes two arguments: double x and double y, which represent the x and y coordinates of the starting point.

The moveTo method is typically called first when defining a Path, as it sets the starting point for the subsequent path elements. For example, you might use the moveTo method to set the starting point for a line or curve, or to start a new subpath.

lineTo property in the Path widget in Flutter is used to add a straight line segment to the Path. It takes two arguments: double x and double y, which represent the x and y coordinates of the end point of the line segment.

The lineTo method is typically called after the moveTo method to add a straight line segment to the Path. The line segment starts at the last point in the Path, which is set by the previous moveTo or lineTo method.

Next let's create a custom clipper class that extends the CustomClipper<Path> class. This class is used to define the shape that is used to clip the child widget. We'll pass an instance of this class as the clipper argument to the ClipPath widget.

class _StarClipper extends CustomClipper<Path> {
  @override
  Path getClip(Size size) {
    return _starPath();
  }

  @override
  bool shouldReclip(CustomClipper<Path> oldClipper) => false;
}

In this code, the _StarClipper class extends the CustomClipper<Path> class and implements the getClip method. The getClip method takes the Size of the child widget as an argument, and it returns the _starPath as the shape that is used to clip the child widget.

The shouldReclip method returns false, which means that the clipper will not be re-clipped unless the underlying data changes.

After that let's use the ClipPath widget to clip a child widget with the star shape. We'll pass the _StarClipper method as the clipper argument to the ClipPath widget.

ClipPath(
  clipper: _StarClipper(),
  child: Container(
    width: 100.0,
    height: 100.0,
    color: Colors.yellow,
  ),
),

In this code, the ClipPath widget takes a Container widget as its child. The Container widget has a width of 100.0 and a height of 100.0, and it's filled with the color yellow. The ClipPath widget uses the _StarClipper method as its clipper, which clips the child Container widget into a star shape.

Here's the full code for the ClipPath example:

class StarClippingExample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ClipPath(
          clipper: _StarClipper(),
          child: Container(
            width: 100.0,
            height: 100.0,
            color: Colors.yellow,
          ),
        ),
      ),
    );
  }
}

Path _starPath() {
  return Path()
    ..moveTo(50.0, 0.0)
    ..lineTo(61.0, 35.0)
    ..lineTo(98.0, 35.0)
    ..lineTo(68.0, 58.0)
    ..lineTo(79.0, 95.0)
    ..lineTo(50.0, 70.0)
    ..lineTo(21.0, 95.0)
    ..lineTo(32.0, 58.0)
    ..lineTo(2.0, 35.0)
    ..lineTo(39.0, 35.0)
    ..close();
}

class _StarClipper extends CustomClipper<Path> {
  @override
  Path getClip(Size size) {
    return _starPath();
  }

  @override
  bool shouldReclip(CustomClipper<Path> oldClipper) => false;
}

In this example, we've created a ClipPath widget that uses a Path clipper to clip a yellow Container into a star shape. By using the ClipPath widget and the Path clipper, we can easily create complex shapes to clip child widgets in Flutter.