我需要一个导航栏，当在Flutter中单击图标时可以在其上展开图标Bottom Navigation bar design image
答案 0 :(得分：1)
我刚刚编辑了底部导航条
import 'package:flutter/material.dart';
import 'dart:collection' show Queue;
import 'dart:math' as math;
import 'package:flutter/widgets.dart';
import 'package:vector_math/vector_math_64.dart' show Vector3;
enum BottomNavigationBarType {
fixed,
shifting,
}
class CoBottomNavigationBar extends StatefulWidget {
CoBottomNavigationBar({
Key key,
@required this.items,
this.onTap,
this.currentIndex = 0,
this.elevation = 8.0,
BottomNavigationBarType type,
Color fixedColor,
this.backgroundColor,
this.iconSize = 24.0,
Color selectedItemColor,
this.unselectedItemColor,
this.selectedFontSize = 14.0,
this.unselectedFontSize = 1,
this.showSelectedLabels = true,
bool showUnselectedLabels,
}) : assert(items != null),
assert(items.length >= 2),
assert(
items.every((BottomNavigationBarItem item) => item.title != null) ==
true,
'Every item must have a non-null title',
),
assert(0 <= currentIndex && currentIndex < items.length),
assert(elevation != null && elevation >= 0.0),
assert(iconSize != null && iconSize >= 0.0),
assert(selectedItemColor != null ? fixedColor == null : true,
'Either selectedItemColor or fixedColor can be specified, but not both'),
assert(selectedFontSize != null && selectedFontSize >= 0.0),
assert(unselectedFontSize != null && unselectedFontSize >= 0.0),
assert(showSelectedLabels != null),
type = _type(type, items),
selectedItemColor = selectedItemColor ?? fixedColor,
showUnselectedLabels =
showUnselectedLabels ?? _defaultShowUnselected(_type(type, items)),
super(key: key);
final List<BottomNavigationBarItem> items;
/// `setState` to rebuild the bottom navigation bar with the new [currentIndex].
final ValueChanged<int> onTap;
/// The index into [items] for the current active [BottomNavigationBarItem].
final int currentIndex;
/// The z-coordinate of this [BottomNavigationBar].
///
/// If null, defaults to `8.0`.
///
/// {@macro flutter.material.material.elevation}
final double elevation;
/// Defines the layout and behavior of a [BottomNavigationBar].
///
/// See documentation for [BottomNavigationBarType] for information on the
/// meaning of different types.
final BottomNavigationBarType type;
/// The value of [selectedItemColor].
///
/// This getter only exists for backwards compatibility, the
/// [selectedItemColor] property is preferred.
Color get fixedColor => selectedItemColor;
/// The color of the [BottomNavigationBar] itself.
///
/// If [type] is [BottomNavigationBarType.shifting] and the
/// [items]s, have [BottomNavigationBarItem.backgroundColor] set, the [item]'s
/// backgroundColor will splash and overwrite this color.
final Color backgroundColor;
/// The size of all of the [BottomNavigationBarItem] icons.
///
/// See [BottomNavigationBarItem.icon] for more information.
final double iconSize;
/// The color of the selected [BottomNavigationBarItem.icon] and
/// [BottomNavigationBarItem.label].
///
/// If null then the [ThemeData.primaryColor] is used.
final Color selectedItemColor;
/// The color of the unselected [BottomNavigationBarItem.icon] and
/// [BottomNavigationBarItem.label]s.
///
/// If null then the [TextTheme.caption]'s color is used.
final Color unselectedItemColor;
/// The font size of the [BottomNavigationBarItem] labels when they are selected.
///
/// Defaults to `14.0`.
final double selectedFontSize;
/// The font size of the [BottomNavigationBarItem] labels when they are not
/// selected.
///
/// Defaults to `12.0`.
final double unselectedFontSize;
/// Whether the labels are shown for the selected [BottomNavigationBarItem].
final bool showUnselectedLabels;
/// Whether the labels are shown for the unselected [BottomNavigationBarItem]s.
final bool showSelectedLabels;
// Used by the [BottomNavigationBar] constructor to set the [type] parameter.
//
// If type is provided, it is returned. Otherwise,
// [BottomNavigationBarType.fixed] is used for 3 or fewer items, and
// [BottomNavigationBarType.shifting] is used for 4+ items.
static BottomNavigationBarType _type(
BottomNavigationBarType type,
List<BottomNavigationBarItem> items,
) {
if (type != null) {
return type;
}
return items.length <= 3
? BottomNavigationBarType.fixed
: BottomNavigationBarType.shifting;
}
// Used by the [BottomNavigationBar] constructor to set the [showUnselected]
// parameter.
//
// Unselected labels are shown by default for [BottomNavigationBarType.fixed],
// and hidden by default for [BottomNavigationBarType.shifting].
static bool _defaultShowUnselected(BottomNavigationBarType type) {
switch (type) {
case BottomNavigationBarType.shifting:
return false;
case BottomNavigationBarType.fixed:
return true;
}
assert(false);
return false;
}
@override
_BottomNavigationBarState createState() => _BottomNavigationBarState();
}
// This represents a single tile in the bottom navigation bar. It is intended
// to go into a flex container.
class _BottomNavigationTile extends StatelessWidget {
const _BottomNavigationTile(
this.type,
this.item,
this.animation,
this.iconSize, {
this.onTap,
this.colorTween,
this.flex,
this.selected = false,
@required this.selectedFontSize,
@required this.unselectedFontSize,
this.showSelectedLabels,
this.showUnselectedLabels,
this.indexLabel,
}) : assert(type != null),
assert(item != null),
assert(animation != null),
assert(selected != null),
assert(selectedFontSize != null && selectedFontSize >= 0),
assert(unselectedFontSize != null && unselectedFontSize >= 0);
final BottomNavigationBarType type;
final BottomNavigationBarItem item;
final Animation<double> animation;
final double iconSize;
final VoidCallback onTap;
final ColorTween colorTween;
final double flex;
final bool selected;
final double selectedFontSize;
final double unselectedFontSize;
final String indexLabel;
final bool showSelectedLabels;
final bool showUnselectedLabels;
@override
Widget build(BuildContext context) {
// In order to use the flex container to grow the tile during animation, we
// need to divide the changes in flex allotment into smaller pieces to
// produce smooth animation. We do this by multiplying the flex value
// (which is an integer) by a large number.
int size;
double bottomPadding = 14;
double topPadding = selectedFontSize / 2.0;
if (showSelectedLabels && !showUnselectedLabels) {
bottomPadding = Tween<double>(
begin: 0.0,
end: 14,
).evaluate(animation);
topPadding = Tween<double>(
begin: selectedFontSize,
end: selectedFontSize / 2.0,
).evaluate(animation);
}
// Center all icons if no labels are shown.
if (!showSelectedLabels && !showUnselectedLabels) {
bottomPadding = 14;
topPadding = selectedFontSize;
}
switch (type) {
case BottomNavigationBarType.fixed:
size = 1;
break;
case BottomNavigationBarType.shifting:
size = (flex * 1000.0).round();
break;
}
Color _color=selected?item.backgroundColor:colorTween.evaluate(animation);
Widget _label1 = selected? _Label(
colorTween: _color,
animation: animation,
item: item,
selectedFontSize: selectedFontSize,
unselectedFontSize: unselectedFontSize,
showSelectedLabels: showSelectedLabels,
showUnselectedLabels: showUnselectedLabels,
):Text("");
BoxDecoration _mydecoration= selected ? BoxDecoration(
color: item.backgroundColor.withOpacity(0.5),
borderRadius: BorderRadius.all(Radius.circular(20)),):
BoxDecoration(color: Colors.white);
return Expanded(
flex: size,
child: Semantics(
container: true,
header: true,
selected: selected,
child: Stack(
children: <Widget>[
InkResponse(
onTap: onTap,
child: Container(
decoration: _mydecoration,
padding: EdgeInsets.only(top: 10,left: 10,right: 10,bottom: 10),
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
_TileIcon(
colorTween: colorTween,
animation: animation,
iconSize: iconSize,
selected: selected,
item: item,
),
_label1,
],
),
),
),
Semantics(
label: indexLabel,
),
],
),
),
);
}
}
class _TileIcon extends StatelessWidget {
const _TileIcon({
Key key,
@required this.colorTween,
@required this.animation,
@required this.iconSize,
@required this.selected,
@required this.item,
}) : assert(selected != null),
assert(item != null),
super(key: key);
final ColorTween colorTween;
final Animation<double> animation;
final double iconSize;
final bool selected;
final BottomNavigationBarItem item;
@override
Widget build(BuildContext context) {
final Color iconColor = selected?item.backgroundColor:colorTween.evaluate(animation);
return Align(
alignment: Alignment.topCenter,
heightFactor: 1.0,
child: Container(
child: IconTheme(
data: IconThemeData(
color: iconColor,
size: iconSize,
),
child: selected ? item.activeIcon : item.icon,
),
),
);
}
}
class _Label extends StatelessWidget {
const _Label({
Key key,
@required this.colorTween,
@required this.animation,
@required this.item,
@required this.selectedFontSize,
@required this.unselectedFontSize,
@required this.showSelectedLabels,
@required this.showUnselectedLabels,
}) : assert(colorTween != null),
assert(animation != null),
assert(item != null),
assert(selectedFontSize != null),
assert(unselectedFontSize != null),
assert(showSelectedLabels != null),
assert(showUnselectedLabels != null),
super(key: key);
final Color colorTween;
final Animation<double> animation;
final BottomNavigationBarItem item;
final double selectedFontSize;
final double unselectedFontSize;
final bool showSelectedLabels;
final bool showUnselectedLabels;
@override
Widget build(BuildContext context) {
Widget text = DefaultTextStyle.merge(
style: TextStyle(
fontSize: selectedFontSize,
color: colorTween,
),
// The font size should grow here when active, but because of the way
// font rendering works, it doesn't grow smoothly if we just animate
// the font size, so we use a transform instead.
child: Transform(
transform: Matrix4.diagonal3(
Vector3.all(
Tween<double>(
begin: 0 / selectedFontSize,
end: 1.0,
).evaluate(animation),
),
),
alignment: Alignment.bottomCenter,
child: item.title,
),
);
if (!showUnselectedLabels && !showSelectedLabels) {
// Never show any labels.
text = Opacity(
alwaysIncludeSemantics: true,
opacity: 1.0,
child: text,
);
} else if (!showUnselectedLabels) {
// Fade selected labels in.
text = FadeTransition(
alwaysIncludeSemantics: true,
opacity: animation,
child: text,
);
} else if (!showSelectedLabels) {
// Fade selected labels out.
text = FadeTransition(
alwaysIncludeSemantics: true,
opacity: Tween<double>(begin: 1.0, end: 0.0).animate(animation),
child: text,
);
}
return Align(
alignment: Alignment.bottomCenter,
heightFactor: 1.0,
child: Container(child: text),
);
}
}
class _BottomNavigationBarState extends State<CoBottomNavigationBar>
with TickerProviderStateMixin {
List<AnimationController> _controllers = <AnimationController>[];
List<CurvedAnimation> _animations;
// A queue of color splashes currently being animated.
final Queue<_Circle> _circles = Queue<_Circle>();
// Last splash circle's color, and the final color of the control after
// animation is complete.
Color _backgroundColor;
static final Animatable<double> _flexTween =
Tween<double>(begin: 1.0, end: 1.5);
void _resetState() {
for (AnimationController controller in _controllers) controller.dispose();
for (_Circle circle in _circles) circle.dispose();
_circles.clear();
_controllers =
List<AnimationController>.generate(widget.items.length, (int index) {
return AnimationController(
duration: kThemeAnimationDuration,
vsync: this,
)..addListener(_rebuild);
});
_animations =
List<CurvedAnimation>.generate(widget.items.length, (int index) {
return CurvedAnimation(
parent: _controllers[index],
curve: Curves.fastOutSlowIn,
reverseCurve: Curves.fastOutSlowIn.flipped,
);
});
_controllers[widget.currentIndex].value = 1.0;
_backgroundColor = Colors.white;
}
@override
void initState() {
super.initState();
_resetState();
}
void _rebuild() {
setState(() {
// Rebuilding when any of the controllers tick, i.e. when the items are
// animated.
});
}
@override
void dispose() {
for (AnimationController controller in _controllers) controller.dispose();
for (_Circle circle in _circles) circle.dispose();
super.dispose();
}
double _evaluateFlex(Animation<double> animation) =>
_flexTween.evaluate(animation);
void _pushCircle(int index) {
if (widget.items[index].backgroundColor != null) {
_circles.add(
_Circle(
state: this,
index: index,
color: Colors.white,
vsync: this,
)..controller.addStatusListener(
(AnimationStatus status) {
switch (status) {
case AnimationStatus.completed:
setState(() {
final _Circle circle = _circles.removeFirst();
_backgroundColor = circle.color;
circle.dispose();
});
break;
case AnimationStatus.dismissed:
case AnimationStatus.forward:
case AnimationStatus.reverse:
break;
}
},
),
);
}
}
@override
void didUpdateWidget(CoBottomNavigationBar oldWidget) {
super.didUpdateWidget(oldWidget);
// No animated segue if the length of the items list changes.
if (widget.items.length != oldWidget.items.length) {
_resetState();
return;
}
if (widget.currentIndex != oldWidget.currentIndex) {
switch (widget.type) {
case BottomNavigationBarType.fixed:
break;
case BottomNavigationBarType.shifting:
_pushCircle(widget.currentIndex);
break;
}
_controllers[oldWidget.currentIndex].reverse();
_controllers[widget.currentIndex].forward();
} else {
if (_backgroundColor != widget.items[widget.currentIndex].backgroundColor)
_backgroundColor = Colors.white;
}
}
List<Widget> _createTiles() {
final MaterialLocalizations localizations =
MaterialLocalizations.of(context);
assert(localizations != null);
final ThemeData themeData = Theme.of(context);
Color themeColor;
switch (themeData.brightness) {
case Brightness.light:
themeColor = themeData.primaryColor;
break;
case Brightness.dark:
themeColor = themeData.accentColor;
break;
}
ColorTween colorTween;
switch (widget.type) {
case BottomNavigationBarType.fixed:
colorTween = ColorTween(
begin:
widget.unselectedItemColor ?? themeData.textTheme.caption.color,
end: widget.selectedItemColor ?? widget.fixedColor ?? themeColor,
);
break;
case BottomNavigationBarType.shifting:
colorTween = ColorTween(
begin: widget.unselectedItemColor ?? Colors.white,
end: widget.selectedItemColor ?? Colors.white,
);
break;
}
final List<Widget> tiles = <Widget>[];
for (int i = 0; i < widget.items.length; i++) {
tiles.add(_BottomNavigationTile(
widget.type,
widget.items[i],
_animations[i],
widget.iconSize,
selectedFontSize: widget.selectedFontSize,
unselectedFontSize: 1,
onTap: () {
if (widget.onTap != null) widget.onTap(i);
},
colorTween: colorTween,
flex: _evaluateFlex(_animations[i]),
selected: i == widget.currentIndex,
showSelectedLabels: widget.showSelectedLabels,
showUnselectedLabels: widget.showUnselectedLabels,
indexLabel: localizations.tabLabel(
tabIndex: i + 1, tabCount: widget.items.length),
));
}
return tiles;
}
Widget _createContainer(List<Widget> tiles) {
return DefaultTextStyle.merge(
overflow: TextOverflow.ellipsis,
child: Padding(
padding: EdgeInsets.only(left: 16, right: 16,top:16,bottom:16),
child: Row(
children: tiles,
),
),
);
}
@override
Widget build(BuildContext context) {
assert(debugCheckHasDirectionality(context));
assert(debugCheckHasMaterialLocalizations(context));
assert(debugCheckHasMediaQuery(context));
// Labels apply up to _bottomMargin padding. Remainder is media padding.
final double additionalBottomPadding = math.max(
MediaQuery.of(context).padding.bottom - widget.selectedFontSize / 2.0,
0.0);
Color backgroundColor;
switch (widget.type) {
case BottomNavigationBarType.fixed:
backgroundColor = widget.backgroundColor;
break;
case BottomNavigationBarType.shifting:
backgroundColor = Colors.white;
break;
}
return Semantics(
explicitChildNodes: true,
child: Material(
elevation: widget.elevation,
color: backgroundColor,
child: ConstrainedBox(
constraints: BoxConstraints(
minHeight: kBottomNavigationBarHeight + additionalBottomPadding),
child: CustomPaint(
painter: _RadialPainter(
circles: _circles.toList(),
textDirection: Directionality.of(context),
),
child: Material(
// Splashes.
type: MaterialType.transparency,
child: MediaQuery.removePadding(
context: context,
removeBottom: true,
child: _createContainer(_createTiles()),
),
),
),
),
),
);
}
}
// Describes an animating color splash circle.
class _Circle {
_Circle({
@required this.state,
@required this.index,
@required this.color,
@required TickerProvider vsync,
}) : assert(state != null),
assert(index != null),
assert(color != null) {
controller = AnimationController(
duration: kThemeAnimationDuration,
vsync: vsync,
);
animation = CurvedAnimation(
parent: controller,
curve: Curves.fastOutSlowIn,
);
controller.forward();
}
final _BottomNavigationBarState state;
final int index;
final Color color;
AnimationController controller;
CurvedAnimation animation;
double get horizontalLeadingOffset {
double weightSum(Iterable<Animation<double>> animations) {
// We're adding flex values instead of animation values to produce correct
// ratios.
return animations
.map<double>(state._evaluateFlex)
.fold<double>(0.0, (double sum, double value) => sum + value);
}
final double allWeights = weightSum(state._animations);
// These weights sum to the start edge of the indexed item.
final double leadingWeights =
weightSum(state._animations.sublist(0, index));
// Add half of its flex value in order to get to the center.
return (leadingWeights +
state._evaluateFlex(state._animations[index]) / 2.0) /
allWeights;
}
void dispose() {
controller.dispose();
}
}
// Paints the animating color splash circles.
class _RadialPainter extends CustomPainter {
_RadialPainter({
@required this.circles,
@required this.textDirection,
}) : assert(circles != null),
assert(textDirection != null);
final List<_Circle> circles;
final TextDirection textDirection;
// Computes the maximum radius attainable such that at least one of the
// bounding rectangle's corners touches the edge of the circle. Drawing a
// circle larger than this radius is not needed, since there is no perceivable
// difference within the cropped rectangle.
static double _maxRadius(Offset center, Size size) {
final double maxX = math.max(center.dx, size.width - center.dx);
final double maxY = math.max(center.dy, size.height - center.dy);
return math.sqrt(maxX * maxX + maxY * maxY);
}
@override
bool shouldRepaint(_RadialPainter oldPainter) {
if (textDirection != oldPainter.textDirection) return true;
if (circles == oldPainter.circles) return false;
if (circles.length != oldPainter.circles.length) return true;
for (int i = 0; i < circles.length; i += 1)
if (circles[i] != oldPainter.circles[i]) return true;
return false;
}
@override
void paint(Canvas canvas, Size size) {
for (_Circle circle in circles) {
final Paint paint = Paint()..color = circle.color;
final Rect rect = Rect.fromLTWH(0.0, 0.0, size.width, size.height);
canvas.clipRect(rect);
double leftFraction;
switch (textDirection) {
case TextDirection.rtl:
leftFraction = 1.0 - circle.horizontalLeadingOffset;
break;
case TextDirection.ltr:
leftFraction = circle.horizontalLeadingOffset;
break;
}
final Offset center =
Offset(leftFraction * size.width, size.height / 2.0);
final Tween<double> radiusTween = Tween<double>(
begin: 0.0,
end: _maxRadius(center, size),
);
canvas.drawCircle(
center,
radiusTween.transform(circle.animation.value),
paint,
);
}
}
}
您现在可以将其用作
bottomNavigationBar: CoBottomNavigationBar(
selectedFontSize: 16,
currentIndex: _selectedIndex,
selectedItemColor:Colors.yellow,
unselectedItemColor: Colors.black45,
onTap: _onItemTapped,
showUnselectedLabels: false,
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(
Icons.home,
),
title: Text(
' Home',
),
backgroundColor: Colors.red,
),
BottomNavigationBarItem(
icon: Icon(
Icons.thumb_up,
),
title: Text(
" Likes",
),
backgroundColor: Colors.blue,
),
BottomNavigationBarItem(
icon: Icon(
Icons.search,
),
title: Text(
' Search',
),
backgroundColor: Colors.pink,
),
BottomNavigationBarItem(
icon: Icon(
Icons.star,
),
title: Text(
" Profile",
),
backgroundColor: Colors.purple,
),
],
),