如何在 Flutter 中自定义 Slider 小部件？

Question

是否可以在 Flutter 中自定义 Slider Widget？

像这样：

Answer 1

用 SliderTheme 包裹你的滑块

SliderTheme(
    data: SliderThemeData(
            thumbColor: Colors.green,
            thumbShape: RoundSliderThumbShape(enabledThumbRadius: 20)),
    child: Slider(
          value: _value,
          onChanged: (val) {
            _value = val;
            setState(() {});
          },
        ),
      ),

Answer 2

我认为你必须使用 SliderTickMarkShape 类

滑块刻度线形状的基类。

如果您想要自定义滑块刻度线形状，请创建此子类。

简单的方法是获取在您的上下文中使用的实际 SliderTheme 并仅修改您需要的属性。 例如，要修改一张幻灯片：

SliderTheme(
    data: SliderTheme.of(context).copyWith(
    activeTrackColor: Colors.white,
    thumbShape: RoundSliderThumbShape(enabledThumbRadius: 15.0),
    overlayShape: RoundSliderOverlayShape(overlayRadius: 30.0),
    ),
    child: Slider(
             value: height.toDouble(),
             min: 120.0,
             max: 220.0,
             activeColor: Colors.white,
             inactiveColor: Color(0xFF8D8E98),
             onChanged: (double newValue) {
                 setState(() {
                        height = newValue.round();
                      });
                    },
                  ),
                ),

另一种选择是修改您在应用中使用的主题； 通过这种方式，您可以修改应用程序中的所有滑块：

MaterialApp(
      theme: ThemeData.dark().copyWith(
          sliderTheme: SliderTheme.of(context).copyWith( //slider modifications
            thumbColor: Color(0xFFEB1555),
            inactiveTrackColor: Color(0xFF8D8E98),
            activeTrackColor: Colors.white,
            overlayColor: Color(0x99EB1555),
            thumbShape: RoundSliderThumbShape(enabledThumbRadius: 15.0),
            overlayShape: RoundSliderOverlayShape(overlayRadius: 30.0),
          ),
          primaryColor: Color(0xFF0A0E21), // theme color
          scaffoldBackgroundColor: Color(0xFF0A0E21)), // theme background color
      home: InputPage(),
);

Answer 3

我记得，我也遇到过同样的挑战。

我创建了自己的波浪滑块：

import 'dart:math';

import 'package:flutter/material.dart';

List<int> bars = [];
const barWidth = 5.0;
double screenWidth;
int numberOfBars;

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Home(),
    );
  }
}

void randomNumberGenerator() {
  Random r = Random();
  for (var i = 0; i < numberOfBars; i++) {
    bars.add(r.nextInt(40) + 10);
  }
}

class Home extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    if (bars.isEmpty) {
      screenWidth = MediaQuery.of(context).size.width;
      numberOfBars = screenWidth ~/ barWidth;
      randomNumberGenerator();
    }
    return Container(child: WaveSlider());
  }
}

class WaveSlider extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => WaveSliderState();
}

class WaveSliderState extends State<WaveSlider> {
  double bar2Position = 180.0;

  _onTapDown(TapDownDetails details) {
    var x = details.globalPosition.dx;
    print("tap down " + x.toString());
    setState(() {
      bar2Position = x;
    });
  }

  @override
  Widget build(BuildContext context) {
    int barItem = 0;
    return Scaffold(
      body: Center(
        child: Stack(
          alignment: Alignment.centerLeft,
          children: <Widget>[
            GestureDetector(
              onTapDown: (TapDownDetails details) => _onTapDown(details),
              onHorizontalDragUpdate: (DragUpdateDetails details) {
                setState(() {
                  bar2Position = details.globalPosition.dx;
                });
              },
              child: Container(
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.end,
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: bars.map((int height) {
                    Color color = barItem + 1 < bar2Position / barWidth
                        ? Colors.deepPurple
                        : Colors.blueGrey;
                    barItem++;
                    return Container(
                      color: color,
                      height: height.toDouble(),
                      width: 5.0,
                    );
                  }).toList(),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}