build method
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:
- the fields of the widget, which themselves must not change over time, and
- any ambient state obtained from the
context
using BuildContext.dependOnInheritedWidgetOfExactType.
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 fill-rule="evenodd" clip-rule="evenodd" d="M15.25 5C15.25 4.58579 15.5858 4.25 16 4.25H22C22.4142 4.25 22.75 4.58579 22.75 5C22.75 5.41421 22.4142 5.75 22 5.75H16C15.5858 5.75 15.25 5.41421 15.25 5Z" fill="currentColor"/>
<path d="M7.94474 5.18374C9.03866 3.95307 10.9615 3.95308 12.0555 5.18374L17.3795 11.1733C18.3057 12.2152 18.3058 13.7855 17.3796 14.8273L12.0555 20.8169C10.9615 22.0476 9.03866 22.0477 7.94474 20.8169L2.62067 14.8273C1.69451 13.7855 1.69449 12.2152 2.62064 11.1734L7.94474 5.18374Z" fill="currentColor"/>
</svg>
''',
colorFilter:
color != null ? widgets.ColorFilter.mode(color!, widgets.BlendMode.srcIn) : null,
width: width,
height: height,
);