// Copyright 2015 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter/rendering.dart'; import 'basic.dart'; import 'debug.dart'; import 'framework.dart'; import 'icon_data.dart'; import 'icon_theme.dart'; import 'icon_theme_data.dart'; /// A graphical icon widget drawn with a glyph from a font described in /// an [IconData] such as material's predefined [IconData]s in [Icons]. /// /// Icons are not interactive. For an interactive icon, consider material's /// [IconButton]. /// /// There must be an ambient [Directionality] widget when using [Icon]. /// Typically this is introduced automatically by the [WidgetsApp] or /// [MaterialApp]. /// /// This widget assumes that the rendered icon is squared. Non-squared icons may /// render incorrectly. /// /// {@tool sample} /// /// This example shows how to use [Icon] to create an addition icon, in the /// color pink, and 30 x 30 pixels in size. /// /// ```dart /// Icon( /// Icons.add, /// color: Colors.pink, /// size: 30.0, /// ) /// ``` /// {@end-tool} /// /// See also: /// /// * [IconButton], for interactive icons. /// * [Icons], for the list of available icons for use with this class. /// * [IconTheme], which provides ambient configuration for icons. /// * [ImageIcon], for showing icons from [AssetImage]s or other [ImageProvider]s. class Icon extends StatelessWidget { /// Creates an icon. /// /// The [size] and [color] default to the value given by the current [IconTheme]. const Icon( this.icon, { Key key, this.size, this.color, this.semanticLabel, this.textDirection, }) : super(key: key); /// The icon to display. The available icons are described in [Icons]. /// /// The icon can be null, in which case the widget will render as an empty /// space of the specified [size]. final IconData icon; /// The size of the icon in logical pixels. /// /// Icons occupy a square with width and height equal to size. /// /// Defaults to the current [IconTheme] size, if any. If there is no /// [IconTheme], or it does not specify an explicit size, then it defaults to /// 24.0. /// /// If this [Icon] is being placed inside an [IconButton], then use /// [IconButton.iconSize] instead, so that the [IconButton] can make the splash /// area the appropriate size as well. The [IconButton] uses an [IconTheme] to /// pass down the size to the [Icon]. final double size; /// The color to use when drawing the icon. /// /// Defaults to the current [IconTheme] color, if any. /// /// The given color will be adjusted by the opacity of the current /// [IconTheme], if any. /// /// /// In material apps, if there is a [Theme] without any [IconTheme]s /// specified, icon colors default to white if the theme is dark /// and black if the theme is light. /// /// If no [IconTheme] and no [Theme] is specified, icons will default to black. /// /// See [Theme] to set the current theme and [ThemeData.brightness] /// for setting the current theme's brightness. /// /// Typically, a material design color will be used, as follows: /// /// ```dart /// Icon( /// icon: Icons.widgets, /// color: Colors.blue.shade400, /// ) /// ``` final Color color; /// Semantic label for the icon. /// /// Announced in accessibility modes (e.g TalkBack/VoiceOver). /// This label does not show in the UI. /// /// See also: /// /// * [Semantics.label], which is set to [semanticLabel] in the underlying /// [Semantics] widget. final String semanticLabel; /// The text direction to use for rendering the icon. /// /// If this is null, the ambient [Directionality] is used instead. /// /// Some icons follow the reading direction. For example, "back" buttons point /// left in left-to-right environments and right in right-to-left /// environments. Such icons have their [IconData.matchTextDirection] field /// set to true, and the [Icon] widget uses the [textDirection] to determine /// the orientation in which to draw the icon. /// /// This property has no effect if the [icon]'s [IconData.matchTextDirection] /// field is false, but for consistency a text direction value must always be /// specified, either directly using this property or using [Directionality]. final TextDirection textDirection; @override Widget build(BuildContext context) { assert(this.textDirection != null || debugCheckHasDirectionality(context)); final TextDirection textDirection = this.textDirection ?? Directionality.of(context); final IconThemeData iconTheme = IconTheme.of(context); final double iconSize = size ?? iconTheme.size; if (icon == null) { return Semantics( label: semanticLabel, child: SizedBox(width: iconSize, height: iconSize), ); } final double iconOpacity = iconTheme.opacity; Color iconColor = color ?? iconTheme.color; if (iconOpacity != 1.0) iconColor = iconColor.withOpacity(iconColor.opacity * iconOpacity); Widget iconWidget = RichText( overflow: TextOverflow.visible, // Never clip. textDirection: textDirection, // Since we already fetched it for the assert... text: TextSpan( text: String.fromCharCode(icon.codePoint), style: TextStyle( inherit: false, color: iconColor, fontSize: iconSize, fontFamily: icon.fontFamily, package: icon.fontPackage, ), ), ); if (icon.matchTextDirection) { switch (textDirection) { case TextDirection.rtl: iconWidget = Transform( transform: Matrix4.identity()..scale(-1.0, 1.0, 1.0), alignment: Alignment.center, transformHitTests: false, child: iconWidget, ); break; case TextDirection.ltr: break; } } return Semantics( label: semanticLabel, child: ExcludeSemantics( child: SizedBox( width: iconSize, height: iconSize, child: Center( child: iconWidget, ), ), ), ); } @override void debugFillProperties(DiagnosticPropertiesBuilder properties) { super.debugFillProperties(properties); properties.add(DiagnosticsProperty<IconData>('icon', icon, ifNull: '<empty>', showName: false)); properties.add(DoubleProperty('size', size, defaultValue: null)); properties.add(DiagnosticsProperty<Color>('color', color, defaultValue: null)); } }