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// 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 'dart:math' as math;
import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';
import 'debug.dart';
import 'icons.dart';
import 'ink_well.dart';
import 'material.dart';
import 'theme.dart';
import 'tooltip.dart';
// Minimum logical pixel size of the IconButton.
// See: <>
const double _kMinButtonSize = 48.0;
/// A material design icon button.
/// An icon button is a picture printed on a [Material] widget that reacts to
/// touches by filling with color (ink).
/// Icon buttons are commonly used in the [AppBar.actions] field, but they can
/// be used in many other places as well.
/// If the [onPressed] callback is null, then the button will be disabled and
/// will not react to touch.
/// Requires one of its ancestors to be a [Material] widget.
/// The hit region of an icon button will, if possible, be at least 48.0 pixels
/// in size, regardless of the actual [iconSize], to satisfy the [touch target
/// size](
/// requirements in the Material Design specification. The [alignment] controls
/// how the icon itself is positioned within the hit region.
/// ## Sample code
/// ```dart
/// new IconButton(
/// icon: new Icon(Icons.volume_up),
/// tooltip: 'Increase volume by 10%',
/// onPressed: () { setState(() { _volume *= 1.1; }); },
/// )
/// ```
/// See also:
/// * [Icons], a library of predefined icons.
/// * [BackButton], an icon button for a "back" affordance which adapts to the
/// current platform's conventions.
/// * [CloseButton], an icon button for closing pages.
/// * [AppBar], to show a toolbar at the top of an application.
/// * [RaisedButton] and [FlatButton], for buttons with text in them.
/// * [InkResponse] and [InkWell], for the ink splash effect itself.
class IconButton extends StatelessWidget {
/// Creates an icon button.
/// Icon buttons are commonly used in the [AppBar.actions] field, but they can
/// be used in many other places as well.
/// Requires one of its ancestors to be a [Material] widget.
/// The [iconSize], [padding], and [alignment] arguments must not be null (though
/// they each have default values).
/// The [icon] argument must be specified, and is typically either an [Icon]
/// or an [ImageIcon].
const IconButton({
Key key,
this.iconSize = 24.0,
this.padding = const EdgeInsets.all(8.0),
this.alignment =,
@required this.icon,
@required this.onPressed,
}) : assert(iconSize != null),
assert(padding != null),
assert(alignment != null),
assert(icon != null),
super(key: key);
/// The size of the icon inside the button.
/// This property must not be null. It defaults to 24.0.
/// The size given here is passed down to the widget in the [icon] property
/// via an [IconTheme]. Setting the size here instead of in, for example, the
/// [Icon.size] property allows the [IconButton] to size the splash area to
/// fit the [Icon]. If you were to set the size of the [Icon] using
/// [Icon.size] instead, then the [IconButton] would default to 24.0 and then
/// the [Icon] itself would likely get clipped.
final double iconSize;
/// The padding around the button's icon. The entire padded icon will react
/// to input gestures.
/// This property must not be null. It defaults to 8.0 padding on all sides.
final EdgeInsetsGeometry padding;
/// Defines how the icon is positioned within the IconButton.
/// This property must not be null. It defaults to [].
/// See also:
/// * [Alignment], a class with convenient constants typically used to
/// specify an [AlignmentGeometry].
/// * [AlignmentDirectional], like [Alignment] for specifying alignments
/// relative to text direction.
final AlignmentGeometry alignment;
/// The icon to display inside the button.
/// The [Icon.size] and [Icon.color] of the icon is configured automatically
/// based on the [iconSize] and [color] properties of _this_ widget using an
/// [IconTheme] and therefore should not be explicitly given in the icon
/// widget.
/// This property must not be null.
/// See [Icon], [ImageIcon].
final Widget icon;
/// The color to use for the icon inside the button, if the icon is enabled.
/// Defaults to leaving this up to the [icon] widget.
/// The icon is enabled if [onPressed] is not null.
/// See also [disabledColor].
/// ```dart
/// new IconButton(
/// color:,
/// onPressed: _handleTap,
/// icon: Icons.widgets,
/// ),
/// ```
final Color color;
/// The primary color of the button when the button is in the down (pressed) state.
/// The splash is represented as a circular overlay that appears above the
/// [highlightColor] overlay. The splash overlay has a center point that matches
/// the hit point of the user touch event. The splash overlay will expand to
/// fill the button area if the touch is held for long enough time. If the splash
/// color has transparency then the highlight and button color will show through.
/// Defaults to the Theme's splash color, [ThemeData.splashColor].
final Color splashColor;
/// The secondary color of the button when the button is in the down (pressed)
/// state. The highlight color is represented as a solid color that is overlaid over the
/// button color (if any). If the highlight color has transparency, the button color
/// will show through. The highlight fades in quickly as the button is held down.
/// Defaults to the Theme's highlight color, [ThemeData.highlightColor].
final Color highlightColor;
/// The color to use for the icon inside the button, if the icon is disabled.
/// Defaults to the [ThemeData.disabledColor] of the current [Theme].
/// The icon is disabled if [onPressed] is null.
/// See also [color].
final Color disabledColor;
/// The callback that is called when the button is tapped or otherwise activated.
/// If this is set to null, the button will be disabled.
final VoidCallback onPressed;
/// Text that describes the action that will occur when the button is pressed.
/// This text is displayed when the user long-presses on the button and is
/// used for accessibility.
final String tooltip;
Widget build(BuildContext context) {
Color currentColor;
if (onPressed != null)
currentColor = color;
currentColor = disabledColor ?? Theme.of(context).disabledColor;
Widget result = new Semantics(
button: true,
enabled: onPressed != null,
child: new ConstrainedBox(
constraints: const BoxConstraints(minWidth: _kMinButtonSize, minHeight: _kMinButtonSize),
child: new Padding(
padding: padding,
child: new SizedBox(
height: iconSize,
width: iconSize,
child: new Align(
alignment: alignment,
child: IconTheme.merge(
data: new IconThemeData(
size: iconSize,
color: currentColor
child: icon
if (tooltip != null) {
result = new Tooltip(
message: tooltip,
child: result
return new InkResponse(
onTap: onPressed,
child: result,
highlightColor: highlightColor ?? Theme.of(context).highlightColor,
splashColor: splashColor ?? Theme.of(context).splashColor,
radius: math.max(
(iconSize + math.min(padding.horizontal, padding.vertical)) * 0.7,
// x 0.5 for diameter -> radius and + 40% overflow derived from other Material apps.
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
properties.add(new DiagnosticsProperty<Widget>('icon', icon, showName: false));
properties.add(new ObjectFlagProperty<VoidCallback>('onPressed', onPressed, ifNull: 'disabled'));
properties.add(new StringProperty('tooltip', tooltip, defaultValue: null, quoted: false));