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 d="M21 7V17C21 19.2091 19.2091 21 17 21H7C4.79086 21 3 19.2091 3 17V7C3 4.79086 4.79086 3 7 3H17C19.2091 3 21 4.79086 21 7Z" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
<path d="M7 8L11 16M7 16L11 8" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
<path d="M17 12V15.4C17 15.7314 16.7314 16 16.4 16H15C13.8954 16 13 15.1046 13 14V14C13 12.8954 13.8954 12 15 12H17ZM17 12V9" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"/>
</svg>
''',
colorFilter:
color != null ? widgets.ColorFilter.mode(color!, widgets.BlendMode.srcIn) : null,
width: width,
height: height,
);