build method

  1. @override
Widget build(
  1. BuildContext context
)
override

Describes the part of the user interface represented by this widget.

The framework calls this method when this widget is inserted into the tree in a given BuildContext and when the dependencies of this widget change (e.g., an InheritedWidget referenced by this widget changes). This method can potentially be called in every frame and should not have any side effects beyond building a widget.

The framework replaces the subtree below this widget with the widget returned by this method, either by updating the existing subtree or by removing the subtree and inflating a new subtree, depending on whether the widget returned by this method can update the root of the existing subtree, as determined by calling Widget.canUpdate.

Typically implementations return a newly created constellation of widgets that are configured with information from this widget's constructor and from the given BuildContext.

The given BuildContext contains information about the location in the tree at which this widget is being built. For example, the context provides the set of inherited widgets for this location in the tree. A given widget might be built with multiple different BuildContext arguments over time if the widget is moved around the tree or if the widget is inserted into the tree in multiple places at once.

The implementation of this method must only depend on:

If a widget's build method is to depend on anything else, use a StatefulWidget instead.

See also:

  • StatelessWidget, which contains the discussion on performance considerations.

Implementation

@override
widgets.Widget build(widgets.BuildContext context) => SvgPicture.string(
      '''
<svg width="24" height="24" viewBox="0 0 24 24" stroke-width="1.5" fill="none" xmlns="http://www.w3.org/2000/svg">
<path d="M12 21C7.02944 21 3 19.2091 3 17C3 14.7909 7.02944 13 12 13C16.9706 13 21 14.7909 21 17C21 19.2091 16.9706 21 12 21Z" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
<path d="M12 2C13.6569 2 15 3.34315 15 5V6H9V5C9 3.34315 10.3431 2 12 2Z" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
<path d="M3.5 15.5L7.5 8.5" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
<path d="M20.5 15.5L16.5 8.5" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
</svg>
''',
      colorFilter:
          color != null ? widgets.ColorFilter.mode(color!, widgets.BlendMode.srcIn) : null,
      width: width,
      height: height,
    );