Flutter - Icon class

April 4, 2018

Flutter 的 Icon widget 可用來顯示 icon。

其建構子如下：

Icon(IconData icon, { Key key, double size, Color color, String semanticLabel, TextDirection textDirection })

屬性如下：

Name	Type	Description
color	Color	The color to use when drawing the icon.
icon	IconData	The icon to display. The available icons are described in Icons.
semanticLabel	String	Semantic label for the icon.
size	double	The size of the icon in logical pixels.
textDirection	TextDirection	The text direction to use for rendering the icon.
hashCode	int	The hash code for this object.
key	Key	Controls how one widget replaces another widget in the tree.
runtimeType	Type	A representation of the runtime type of the object.

方法如下：

Name	Return Type	Description
build(BuildContext context)	Widget	Describes the part of the user interface represented by this widget.
debugFillProperties(DiagnosticPropertiesBuilder description)	void
createElement()	StatelessElement	Creates a StatelessElement to manage this widget’s location in the tree.
debugDescribeChildren()	List	Returns a list of DiagnosticsNode objects describing this node’s children.
noSuchMethod(Invocation invocation)	dynamic	Invoked when a non-existent method or property is accessed.
toDiagnosticsNode({String name, DiagnosticsTreeStyle style })	DiagnosticsNode	Returns a debug representation of the object that is used by debugging tools and by toStringDeep.
toString({DiagnosticLevel minLevel: DiagnosticLevel.debug })	String	Returns a string representation of this object.
toStringDeep({String prefixLineOne: ‘’, String prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug })	String	Returns a string representation of this node and its descendants.
toStringShallow({String joiner: ‘, ‘, DiagnosticLevel minLevel: DiagnosticLevel.debug })	String	Returns a one-line detailed description of the object.
toStringShort()	String	A short, textual description of this widget.

Icon 元件需在 MaterialApp 下使用，所以會要建立 MaterialApp，然後將 Icon 元件塞給 MaterialApp 的 home 屬性。

Icon 元件建立時需要指定要顯示的 Icon，可直接用 Icons 指定內建的 Icon。

其它屬性像是 color 屬性可設定 Icon 的顏色。

import 'package:flutter/material.dart';

void main() {
  runApp(
    new MaterialApp
    (
      home: new Icon
      (
        Icons.flag, 
        color: Colors.white,
      )
    )
  );
}

或是 size 屬性可設定 Icon 的大小。

import 'package:flutter/material.dart';

void main() {
  runApp(
    new MaterialApp
    (
      home: new Icon
      (
        Icons.flag, 
        color: Colors.white,
        size: 100.0,
      )
    )
  );
}

Link

Flutter