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如何在 flutter 中创建笑脸范围 slider 。就像下面的 GIF 图片。
与自定义主题离散我尝试更改拇指形状。但我想将拇指更改为图像。
// 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/material.dart';
class SliderDemo extends StatefulWidget {
static const String routeName = '/material/slider';
@override
_SliderDemoState createState() => new _SliderDemoState();
}
Path _triangle(double size, Offset thumbCenter, {bool invert = false}) {
final Path thumbPath = new Path();
final double height = math.sqrt(3.0) / 2.0;
final double halfSide = size / 2.0;
final double centerHeight = size * height / 3.0;
final double sign = invert ? -1.0 : 1.0;
thumbPath.moveTo(thumbCenter.dx - halfSide, thumbCenter.dy + sign * centerHeight);
thumbPath.lineTo(thumbCenter.dx, thumbCenter.dy - 2.0 * sign * centerHeight);
thumbPath.lineTo(thumbCenter.dx + halfSide, thumbCenter.dy + sign * centerHeight);
thumbPath.close();
return thumbPath;
}
class _CustomThumbShape extends SliderComponentShape {
static const double _thumbSize = 4.0;
static const double _disabledThumbSize = 5.0;
@override
Size getPreferredSize(bool isEnabled, bool isDiscrete) {
return isEnabled ? const Size.fromRadius(_thumbSize) : const Size.fromRadius(_disabledThumbSize);
}
static final Tween<double> sizeTween = new Tween<double>(
begin: _disabledThumbSize,
end: _thumbSize,
);
@override
void paint(
PaintingContext context,
Offset thumbCenter, {
Animation<double> activationAnimation,
Animation<double> enableAnimation,
bool isDiscrete,
TextPainter labelPainter,
RenderBox parentBox,
SliderThemeData sliderTheme,
TextDirection textDirection,
double value,
}) {
final Canvas canvas = context.canvas;
final ColorTween colorTween = new ColorTween(
begin: sliderTheme.disabledThumbColor,
end: sliderTheme.thumbColor,
);
final double size = _thumbSize * sizeTween.evaluate(enableAnimation);
final Path thumbPath = _triangle(size, thumbCenter);
canvas.drawPath(thumbPath, new Paint()..color = colorTween.evaluate(enableAnimation));
}
}
class _CustomValueIndicatorShape extends SliderComponentShape {
static const double _indicatorSize = 4.0;
static const double _disabledIndicatorSize = 3.0;
static const double _slideUpHeight = 40.0;
@override
Size getPreferredSize(bool isEnabled, bool isDiscrete) {
return new Size.fromRadius(isEnabled ? _indicatorSize : _disabledIndicatorSize);
}
static final Tween<double> sizeTween = new Tween<double>(
begin: _disabledIndicatorSize,
end: _indicatorSize,
);
@override
void paint(
PaintingContext context,
Offset thumbCenter, {
Animation<double> activationAnimation,
Animation<double> enableAnimation,
bool isDiscrete,
TextPainter labelPainter,
RenderBox parentBox,
SliderThemeData sliderTheme,
TextDirection textDirection,
double value,
}) {
final Canvas canvas = context.canvas;
final ColorTween enableColor = new ColorTween(
begin: sliderTheme.disabledThumbColor,
end: sliderTheme.valueIndicatorColor,
);
final Tween<double> slideUpTween = new Tween<double>(
begin: 0.0,
end: _slideUpHeight,
);
final double size = _indicatorSize * sizeTween.evaluate(enableAnimation);
final Offset slideUpOffset = new Offset(0.0, -slideUpTween.evaluate(activationAnimation));
final Path thumbPath = _triangle(
size,
thumbCenter + slideUpOffset,
invert: true,
);
final Color paintColor = enableColor.evaluate(enableAnimation).withAlpha((255.0 * activationAnimation.value).round());
canvas.drawPath(
thumbPath,
new Paint()..color = paintColor,
);
canvas.drawLine(
thumbCenter,
thumbCenter + slideUpOffset,
new Paint()
..color = paintColor
..style = PaintingStyle.stroke
..strokeWidth = 2.0);
labelPainter.paint(canvas, thumbCenter + slideUpOffset + new Offset(-labelPainter.width / 2.0, -labelPainter.height - 4.0));
}
}
class _SliderDemoState extends State<SliderDemo> {
double _value = 25.0;
double _discreteValue = 20.0;
@override
Widget build(BuildContext context) {
final ThemeData theme = Theme.of(context);
return new Scaffold(
appBar: new AppBar(title: const Text('Sliders')),
body: new Padding(
padding: const EdgeInsets.symmetric(horizontal: 40.0),
child: new Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Slider(
value: _value,
min: 0.0,
max: 100.0,
onChanged: (double value) {
setState(() {
_value = value;
});
},
),
const Text('Continuous'),
],
),
new Column(
mainAxisSize: MainAxisSize.min,
children: const <Widget>[
const Slider(value: 0.25, onChanged: null),
const Text('Disabled'),
],
),
new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Slider(
value: _discreteValue,
min: 0.0,
max: 200.0,
divisions: 5,
label: '${_discreteValue.round()}',
onChanged: (double value) {
setState(() {
_discreteValue = value;
});
},
),
const Text('Discrete'),
],
),
new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new SliderTheme(
data: theme.sliderTheme.copyWith(
activeTrackColor: Colors.deepPurple,
inactiveTrackColor: Colors.black26,
activeTickMarkColor: Colors.white70,
inactiveTickMarkColor: Colors.black,
overlayColor: Colors.black12,
thumbColor: Colors.red,
valueIndicatorColor: Colors.deepPurpleAccent,
thumbShape: new _CustomThumbShape(),
valueIndicatorShape: new _CustomValueIndicatorShape(),
valueIndicatorTextStyle: theme.accentTextTheme.body2.copyWith(color: Colors.black87),
),
child: new Slider(
value: _discreteValue,
min: 0.0,
max: 10.0,
divisions: 5,
//semanticFormatterCallback: (double value) => value.round().toString(),
label: '${_discreteValue.round()}',
onChanged: (double value) {
setState(() {
_discreteValue = value;
});
},
),
),
const Text('Discrete with Custom Theme'),
],
),
],
),
),
);
}
}
最佳答案
您需要创建自定义 slider 。
让我们拆分任务:
手势:
import 'package:flutter/material.dart';
import 'package:vector_math/vector_math.dart' as v_math;
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(
body: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('How was the help you recived?', style: TextStyle(color: Color(0xFF6f7478), fontSize: 18),),
SizedBox(height: 20),
ReviewSlider()
],
),
),
),
);
}
}
class ReviewSlider extends StatefulWidget {
@override
_ReviewSliderState createState() => _ReviewSliderState();
}
class _ReviewSliderState extends State<ReviewSlider> with SingleTickerProviderStateMixin {
double intitalReviewValue = 2;
final List<String> reviews = ['Terrible', 'Bad', 'Okay', 'Good', 'Great'];
Animation<double> _animation;
AnimationController _controller;
Tween<double> _tween;
double _innerWidth;
double _animationValue;
@override
void initState() {
super.initState();
_controller = AnimationController(
value: intitalReviewValue,
vsync: this,
duration: Duration(milliseconds: 400),
);
_tween = Tween(end: intitalReviewValue);
_animation = _tween.animate(
CurvedAnimation(
curve: Curves.easeIn,
parent: _controller,
),
)..addListener(() {
setState(() {
_animationValue = _animation.value;
});
});
_animationValue = intitalReviewValue;
WidgetsBinding.instance.addPostFrameCallback(_afterLayout);
}
_afterLayout(_) {
setState(() {
_innerWidth = MediaQuery.of(context).size.width - 2 * paddingSize;
});
}
void handleTap(int state) {
_controller.duration = Duration(milliseconds: 400);
_tween.begin = _tween.end;
_tween.end = state.toDouble();
_controller.reset();
_controller.forward();
}
_onDrag(details) {
var newAnimatedValue = _calcAnimatedValueFormDragX(
details.globalPosition.dx,
);
if (newAnimatedValue > 0 && newAnimatedValue < reviews.length - 1) {
setState(
() {
_animationValue = newAnimatedValue;
},
);
}
}
_calcAnimatedValueFormDragX(x) {
return (x - circleDiameter / 2 - paddingSize * 2) / _innerWidth * reviews.length;
}
_onDragEnd(_) {
_controller.duration = Duration(milliseconds: 100);
_tween.begin = _animationValue;
_tween.end = _animationValue.round().toDouble();
_controller.reset();
_controller.forward();
}
@override
void dispose() {
super.dispose();
_controller.dispose();
}
@override
Widget build(BuildContext context) {
return Center(
child: _innerWidth == null
? Container()
: Container(
padding: EdgeInsets.symmetric(horizontal: paddingSize),
height: 200,
child: Stack(children: <Widget>[
MeasureLine(
states: reviews,
handleTap: handleTap,
animationValue: _animationValue,
width: _innerWidth,
),
MyIndicator(
animationValue: _animationValue,
width: _innerWidth,
onDrag: _onDrag,
onDragEnd: _onDragEnd,
),
Text(_animationValue.round().toString()),
]),
),
);
}
}
const double circleDiameter = 60;
const double paddingSize = 10;
class MeasureLine extends StatelessWidget {
MeasureLine({this.handleTap, this.animationValue, this.states, this.width});
final double animationValue;
final Function handleTap;
final List<String> states;
final double width;
List<Widget> _buildUnits() {
var res = <Widget>[];
var animatingUnitIndex = animationValue.round();
var unitAnimatingValue = (animationValue * 10 % 10 / 10 - 0.5).abs() * 2;
states.asMap().forEach((index, text) {
var paddingTop = 0.0;
var scale = 0.7;
var opacity = .3;
if (animatingUnitIndex == index) {
paddingTop = unitAnimatingValue * 5;
scale = (1 - unitAnimatingValue) * 0.7;
opacity = 0.3 + unitAnimatingValue * 0.7;
}
res.add(LimitedBox(
key: ValueKey(text),
maxWidth: circleDiameter,
child: GestureDetector(
onTap: () {
handleTap(index);
},
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
Transform.scale(
scale: scale,
child: Stack(
children: [
Head(),
Face(
color: Colors.white,
animationValue: index.toDouble(),
)
],
)),
Padding(
padding: EdgeInsets.only(top: paddingTop),
child: Opacity(
opacity: opacity,
child: Text(
text,
style: TextStyle(color: Colors.black),
),
),
)
],
),
),
));
});
return res;
}
@override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
Positioned(
top: circleDiameter / 2,
left: 20,
width: width - 40,
child: Container(
width: width,
color: Color(0xFFeceeef),
height: 3,
),
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: _buildUnits(),
),
],
);
}
}
class Face extends StatelessWidget {
Face({
this.color = const Color(0xFF616154),
this.animationValue,
});
final Color color;
final double animationValue;
@override
Widget build(BuildContext context) {
return Container(
height: circleDiameter,
width: circleDiameter,
child: CustomPaint(
size: Size(300, 300),
painter: MyPainter(animationValue, color: color),
),
);
}
}
class MyPainter extends CustomPainter {
MyPainter(
animationValue, {
this.color = const Color(0xFF615f56),
}) : activeIndex = animationValue.floor(),
unitAnimatingValue = (animationValue * 10 % 10 / 10);
Color color;
final int activeIndex;
final double unitAnimatingValue;
@override
void paint(Canvas canvas, Size size) {
_drawEye(canvas, size);
_drawMouth(canvas, size);
}
_drawEye(canvas, size) {
var angle = 0.0;
var wide = 0.0;
switch (activeIndex) {
case 0:
angle = 55 - unitAnimatingValue * 50;
wide = 80.0;
break;
case 1:
wide = 80 - unitAnimatingValue * 80;
angle = 5;
break;
}
var degree1 = 90 * 3 + angle;
var degree2 = 90 * 3 - angle + wide;
var x1 = size.width / 2 * 0.65;
var x2 = size.width - x1;
var y = size.height * 0.41;
var eyeRadius = 5.0;
var paint = Paint()..color = color;
canvas.drawArc(
Rect.fromCircle(
center: Offset(x1, y),
radius: eyeRadius,
),
v_math.radians(degree1),
v_math.radians(360 - wide),
false,
paint,
);
canvas.drawArc(
Rect.fromCircle(
center: Offset(x2, y),
radius: eyeRadius,
),
v_math.radians(degree2),
v_math.radians(360 - wide),
false,
paint,
);
}
_drawMouth(Canvas canvas, size) {
var upperY = size.height * 0.70;
var lowerY = size.height * 0.77;
var middleY = (lowerY - upperY) / 2 + upperY;
var leftX = size.width / 2 * 0.65;
var rightX = size.width - leftX;
var middleX = size.width / 2;
double y1, y3, x2, y2;
Path path2;
switch (activeIndex) {
case 0:
y1 = lowerY;
x2 = middleX;
y2 = upperY;
y3 = lowerY;
break;
case 1:
y1 = lowerY;
x2 = middleX;
y2 = unitAnimatingValue * (middleY - upperY) + upperY;
y3 = lowerY - unitAnimatingValue * (lowerY - upperY);
break;
case 2:
y1 = unitAnimatingValue * (upperY - lowerY) + lowerY;
x2 = middleX;
y2 = unitAnimatingValue * (lowerY + 3 - middleY) + middleY;
y3 = upperY;
break;
case 3:
y1 = upperY;
x2 = middleX;
y2 = lowerY + 3;
y3 = upperY;
path2 = Path()
..moveTo(leftX, y1)
..quadraticBezierTo(
x2,
y2,
upperY - 2.5,
y3 - 2.5,
)
..quadraticBezierTo(
x2,
y2 - unitAnimatingValue * (y2 - upperY + 2.5),
leftX,
upperY - 2.5,
)
..close();
break;
case 4:
y1 = upperY;
x2 = middleX;
y2 = lowerY + 3;
y3 = upperY;
path2 = Path()
..moveTo(leftX, y1)
..quadraticBezierTo(
x2,
y2,
upperY - 2.5,
y3 - 2.5,
)
..quadraticBezierTo(
x2,
upperY - 2.5,
leftX,
upperY - 2.5,
)
..close();
break;
}
var path = Path()
..moveTo(leftX, y1)
..quadraticBezierTo(
x2,
y2,
rightX,
y3,
);
canvas.drawPath(
path,
Paint()
..color = color
..style = PaintingStyle.stroke
..strokeCap = StrokeCap.round
..strokeWidth = 5);
if (path2 != null) {
canvas.drawPath(
path2,
Paint()
..color = color
..style = PaintingStyle.fill
..strokeCap = StrokeCap.round,
);
}
}
@override
bool shouldRepaint(MyPainter oldDelegate) {
return unitAnimatingValue != oldDelegate.unitAnimatingValue ||
activeIndex != oldDelegate.activeIndex;
}
}
class MyIndicator extends StatelessWidget {
MyIndicator({
this.animationValue,
width,
this.onDrag,
this.onDragStart,
this.onDragEnd,
}) : width = width - circleDiameter,
possition = animationValue == 0 ? 0 : animationValue / 4;
final double possition;
final Function onDrag;
final Function onDragStart;
final Function onDragEnd;
final double width;
final double animationValue;
@override
Widget build(BuildContext context) {
return Container(
child: Positioned(
top: 0,
left: width * possition,
child: _buildIndicator(),
),
);
}
_buildIndicator() {
var opacityOfYellow = possition > 0.5 ? 1.0 : possition * 2;
return GestureDetector(
onPanDown: onDragStart,
onPanUpdate: onDrag,
onPanStart: onDrag,
onPanEnd: onDragEnd,
child: Container(
width: circleDiameter,
height: circleDiameter,
child: Stack(
children: <Widget>[
Head(
color: Color(0xFFf4b897),
hasShadow: true,
),
Opacity(
opacity: opacityOfYellow,
child: Head(
color: Color(0xFFfee385),
),
),
Face(
animationValue: animationValue,
)
],
),
),
);
}
}
class Head extends StatelessWidget {
Head({this.color = const Color(0xFFc9ced2), this.hasShadow = false});
final Color color;
final bool hasShadow;
@override
Widget build(BuildContext context) {
return Container(
height: circleDiameter,
width: circleDiameter,
decoration: BoxDecoration(
boxShadow: hasShadow
? [BoxShadow(color: Colors.black26, offset: Offset(0, 2), blurRadius: 5.0)]
: null,
color: color,
shape: BoxShape.circle,
),
);
}
}
关于flutter - 如何在 flutter 中使用拇指创建一个范围 slider 作为png图像,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/51185894/
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