Flutter 带梯度的颤振滑块

我想知道是否有一种方法可以用渐变色在Flutter中创建一个滑块小部件。是指向slider类的链接，但没有“SliderTheme”之类的内容。

我现在基于youtube视频创建了一个自定义轨迹形状类，并在构造函数中添加了渐变属性

如何使用它： 梯度：

LinearGradient gradient = LinearGradient(
 colors: <Color> [
  Colors.red,
  Colors.orange,
  Colors.yellow,
  Colors.green,
  Colors.blue,
  Colors.blue[900],
  Colors.purple
 ]
);

import 'package:flutter/material.dart';

class GradientRectSliderTrackShape extends SliderTrackShape with BaseSliderTrackShape {
  /// Based on https://www.youtube.com/watch?v=Wl4F5V6BoJw
  /// Create a slider track that draws two rectangles with rounded outer edges.
  final LinearGradient gradient;
  final bool darkenInactive;
  const GradientRectSliderTrackShape({ this.gradient: const LinearGradient(colors: [Colors.lightBlue, Colors.blue]), this.darkenInactive: true});

  @override
  void paint(
    PaintingContext context,
    Offset offset, {
    @required RenderBox parentBox,
    @required SliderThemeData sliderTheme,
    @required Animation<double> enableAnimation,
    @required TextDirection textDirection,
    @required Offset thumbCenter,
    bool isDiscrete = false,
    bool isEnabled = false,
    double additionalActiveTrackHeight = 2,
  }) {
    assert(context != null);
    assert(offset != null);
    assert(parentBox != null);
    assert(sliderTheme != null);
    assert(sliderTheme.disabledActiveTrackColor != null);
    assert(sliderTheme.disabledInactiveTrackColor != null);
    assert(sliderTheme.activeTrackColor != null);
    assert(sliderTheme.inactiveTrackColor != null);
    assert(sliderTheme.thumbShape != null);
    assert(enableAnimation != null);
    assert(textDirection != null);
    assert(thumbCenter != null);
    // If the slider [SliderThemeData.trackHeight] is less than or equal to 0,
    // then it makes no difference whether the track is painted or not,
    // therefore the painting  can be a no-op.
    if (sliderTheme.trackHeight <= 0) {
      return;
    }

    final Rect trackRect = getPreferredRect(
      parentBox: parentBox,
      offset: offset,
      sliderTheme: sliderTheme,
      isEnabled: isEnabled,
      isDiscrete: isDiscrete,
    );

    // Assign the track segment paints, which are leading: active and
    // trailing: inactive.
    final ColorTween activeTrackColorTween = ColorTween(begin: sliderTheme.disabledActiveTrackColor, end: sliderTheme.activeTrackColor);
    final ColorTween inactiveTrackColorTween = darkenInactive
      ? ColorTween(begin: sliderTheme.disabledInactiveTrackColor, end: sliderTheme.inactiveTrackColor) 
      : activeTrackColorTween;
    final Paint activePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = activeTrackColorTween.evaluate(enableAnimation);
    final Paint inactivePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = inactiveTrackColorTween.evaluate(enableAnimation);
    Paint leftTrackPaint;
    Paint rightTrackPaint;
    switch (textDirection) {
      case TextDirection.ltr:
        leftTrackPaint = activePaint;
        rightTrackPaint = inactivePaint;
        break;
      case TextDirection.rtl:
        leftTrackPaint = inactivePaint;
        rightTrackPaint = activePaint;
        break;
    }
    final Radius trackRadius = Radius.circular(trackRect.height / 2);
    final Radius activeTrackRadius = Radius.circular(trackRect.height / 2 + 1);

    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        trackRect.left,
        (textDirection == TextDirection.ltr) ? trackRect.top - (additionalActiveTrackHeight / 2): trackRect.top,
        thumbCenter.dx,
        (textDirection == TextDirection.ltr) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius : trackRadius,
        bottomLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius: trackRadius,
      ),
      leftTrackPaint,
    );
    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        thumbCenter.dx,
        (textDirection == TextDirection.rtl) ? trackRect.top - (additionalActiveTrackHeight / 2) : trackRect.top,
        trackRect.right,
        (textDirection == TextDirection.rtl) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
        bottomRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
      ),
      rightTrackPaint,
    );
  }
}

形状类别：

LinearGradient gradient = LinearGradient(
 colors: <Color> [
  Colors.red,
  Colors.orange,
  Colors.yellow,
  Colors.green,
  Colors.blue,
  Colors.blue[900],
  Colors.purple
 ]
);

import 'package:flutter/material.dart';

class GradientRectSliderTrackShape extends SliderTrackShape with BaseSliderTrackShape {
  /// Based on https://www.youtube.com/watch?v=Wl4F5V6BoJw
  /// Create a slider track that draws two rectangles with rounded outer edges.
  final LinearGradient gradient;
  final bool darkenInactive;
  const GradientRectSliderTrackShape({ this.gradient: const LinearGradient(colors: [Colors.lightBlue, Colors.blue]), this.darkenInactive: true});

  @override
  void paint(
    PaintingContext context,
    Offset offset, {
    @required RenderBox parentBox,
    @required SliderThemeData sliderTheme,
    @required Animation<double> enableAnimation,
    @required TextDirection textDirection,
    @required Offset thumbCenter,
    bool isDiscrete = false,
    bool isEnabled = false,
    double additionalActiveTrackHeight = 2,
  }) {
    assert(context != null);
    assert(offset != null);
    assert(parentBox != null);
    assert(sliderTheme != null);
    assert(sliderTheme.disabledActiveTrackColor != null);
    assert(sliderTheme.disabledInactiveTrackColor != null);
    assert(sliderTheme.activeTrackColor != null);
    assert(sliderTheme.inactiveTrackColor != null);
    assert(sliderTheme.thumbShape != null);
    assert(enableAnimation != null);
    assert(textDirection != null);
    assert(thumbCenter != null);
    // If the slider [SliderThemeData.trackHeight] is less than or equal to 0,
    // then it makes no difference whether the track is painted or not,
    // therefore the painting  can be a no-op.
    if (sliderTheme.trackHeight <= 0) {
      return;
    }

    final Rect trackRect = getPreferredRect(
      parentBox: parentBox,
      offset: offset,
      sliderTheme: sliderTheme,
      isEnabled: isEnabled,
      isDiscrete: isDiscrete,
    );

    // Assign the track segment paints, which are leading: active and
    // trailing: inactive.
    final ColorTween activeTrackColorTween = ColorTween(begin: sliderTheme.disabledActiveTrackColor, end: sliderTheme.activeTrackColor);
    final ColorTween inactiveTrackColorTween = darkenInactive
      ? ColorTween(begin: sliderTheme.disabledInactiveTrackColor, end: sliderTheme.inactiveTrackColor) 
      : activeTrackColorTween;
    final Paint activePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = activeTrackColorTween.evaluate(enableAnimation);
    final Paint inactivePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = inactiveTrackColorTween.evaluate(enableAnimation);
    Paint leftTrackPaint;
    Paint rightTrackPaint;
    switch (textDirection) {
      case TextDirection.ltr:
        leftTrackPaint = activePaint;
        rightTrackPaint = inactivePaint;
        break;
      case TextDirection.rtl:
        leftTrackPaint = inactivePaint;
        rightTrackPaint = activePaint;
        break;
    }
    final Radius trackRadius = Radius.circular(trackRect.height / 2);
    final Radius activeTrackRadius = Radius.circular(trackRect.height / 2 + 1);

    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        trackRect.left,
        (textDirection == TextDirection.ltr) ? trackRect.top - (additionalActiveTrackHeight / 2): trackRect.top,
        thumbCenter.dx,
        (textDirection == TextDirection.ltr) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius : trackRadius,
        bottomLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius: trackRadius,
      ),
      leftTrackPaint,
    );
    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        thumbCenter.dx,
        (textDirection == TextDirection.rtl) ? trackRect.top - (additionalActiveTrackHeight / 2) : trackRect.top,
        trackRect.right,
        (textDirection == TextDirection.rtl) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
        bottomRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
      ),
      rightTrackPaint,
    );
  }
}

导入“包装：颤振/材料.省道”；
类GradientRectSliderTrackShape使用BaseSliderTrackShape扩展了SliderTrackShape{
///基于https://www.youtube.com/watch?v=Wl4F5V6BoJw
///创建一个滑块轨迹，用于绘制两个外边缘为圆形的矩形。
最终线性梯度；
最终bool变暗激活；
const gradientrectlidertrackshape（{this.gradient:const LinearGradient（colors:[colors.lightBlue，colors.blue]），this.darkininactive:true}）；
@凌驾
空漆(
绘画语境，
抵消{
@必需的RenderBox父框，
@所需幻灯片主题数据幻灯片主题，
@所需的动画启用，
@所需文本方向文本方向，
@所需偏移拇指中心，
bool isDiscrete=false，
bool isEnabled=false，
双重附加ActiveTrackHeight=2，
}) {
断言（上下文！=null）；
断言（偏移量！=null）；
断言（parentBox！=null）；
断言（sliderTheme！=null）；
断言（sliderTheme.disabledActiveTrackColor！=null）；
断言（sliderTheme.disabledInactiveTrackColor！=null）；
断言（sliderTheme.activeTrackColor！=null）；
断言（sliderTheme.inactiveTrackColor！=null）；
断言（sliderTheme.thumbShape！=null）；
断言（enableAnimation！=null）；
断言（textDirection！=null）；
断言（thumbCenter！=null）；
//如果滑块[SliderThemeData.trackHeight]小于或等于0，
//那么轨道是否上漆也没什么区别，
//因此，这幅画可以是禁止使用的。
if（sliderTheme.trackHeight我现在基于youtube视频创建了一个自定义轨迹形状类，并在构造函数中添加了渐变属性

如何使用它：
梯度：

LinearGradient gradient = LinearGradient(
 colors: <Color> [
  Colors.red,
  Colors.orange,
  Colors.yellow,
  Colors.green,
  Colors.blue,
  Colors.blue[900],
  Colors.purple
 ]
);

import 'package:flutter/material.dart';

class GradientRectSliderTrackShape extends SliderTrackShape with BaseSliderTrackShape {
  /// Based on https://www.youtube.com/watch?v=Wl4F5V6BoJw
  /// Create a slider track that draws two rectangles with rounded outer edges.
  final LinearGradient gradient;
  final bool darkenInactive;
  const GradientRectSliderTrackShape({ this.gradient: const LinearGradient(colors: [Colors.lightBlue, Colors.blue]), this.darkenInactive: true});

  @override
  void paint(
    PaintingContext context,
    Offset offset, {
    @required RenderBox parentBox,
    @required SliderThemeData sliderTheme,
    @required Animation<double> enableAnimation,
    @required TextDirection textDirection,
    @required Offset thumbCenter,
    bool isDiscrete = false,
    bool isEnabled = false,
    double additionalActiveTrackHeight = 2,
  }) {
    assert(context != null);
    assert(offset != null);
    assert(parentBox != null);
    assert(sliderTheme != null);
    assert(sliderTheme.disabledActiveTrackColor != null);
    assert(sliderTheme.disabledInactiveTrackColor != null);
    assert(sliderTheme.activeTrackColor != null);
    assert(sliderTheme.inactiveTrackColor != null);
    assert(sliderTheme.thumbShape != null);
    assert(enableAnimation != null);
    assert(textDirection != null);
    assert(thumbCenter != null);
    // If the slider [SliderThemeData.trackHeight] is less than or equal to 0,
    // then it makes no difference whether the track is painted or not,
    // therefore the painting  can be a no-op.
    if (sliderTheme.trackHeight <= 0) {
      return;
    }

    final Rect trackRect = getPreferredRect(
      parentBox: parentBox,
      offset: offset,
      sliderTheme: sliderTheme,
      isEnabled: isEnabled,
      isDiscrete: isDiscrete,
    );

    // Assign the track segment paints, which are leading: active and
    // trailing: inactive.
    final ColorTween activeTrackColorTween = ColorTween(begin: sliderTheme.disabledActiveTrackColor, end: sliderTheme.activeTrackColor);
    final ColorTween inactiveTrackColorTween = darkenInactive
      ? ColorTween(begin: sliderTheme.disabledInactiveTrackColor, end: sliderTheme.inactiveTrackColor) 
      : activeTrackColorTween;
    final Paint activePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = activeTrackColorTween.evaluate(enableAnimation);
    final Paint inactivePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = inactiveTrackColorTween.evaluate(enableAnimation);
    Paint leftTrackPaint;
    Paint rightTrackPaint;
    switch (textDirection) {
      case TextDirection.ltr:
        leftTrackPaint = activePaint;
        rightTrackPaint = inactivePaint;
        break;
      case TextDirection.rtl:
        leftTrackPaint = inactivePaint;
        rightTrackPaint = activePaint;
        break;
    }
    final Radius trackRadius = Radius.circular(trackRect.height / 2);
    final Radius activeTrackRadius = Radius.circular(trackRect.height / 2 + 1);

    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        trackRect.left,
        (textDirection == TextDirection.ltr) ? trackRect.top - (additionalActiveTrackHeight / 2): trackRect.top,
        thumbCenter.dx,
        (textDirection == TextDirection.ltr) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius : trackRadius,
        bottomLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius: trackRadius,
      ),
      leftTrackPaint,
    );
    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        thumbCenter.dx,
        (textDirection == TextDirection.rtl) ? trackRect.top - (additionalActiveTrackHeight / 2) : trackRect.top,
        trackRect.right,
        (textDirection == TextDirection.rtl) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
        bottomRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
      ),
      rightTrackPaint,
    );
  }
}

形状类别：

LinearGradient gradient = LinearGradient(
 colors: <Color> [
  Colors.red,
  Colors.orange,
  Colors.yellow,
  Colors.green,
  Colors.blue,
  Colors.blue[900],
  Colors.purple
 ]
);

import 'package:flutter/material.dart';

class GradientRectSliderTrackShape extends SliderTrackShape with BaseSliderTrackShape {
  /// Based on https://www.youtube.com/watch?v=Wl4F5V6BoJw
  /// Create a slider track that draws two rectangles with rounded outer edges.
  final LinearGradient gradient;
  final bool darkenInactive;
  const GradientRectSliderTrackShape({ this.gradient: const LinearGradient(colors: [Colors.lightBlue, Colors.blue]), this.darkenInactive: true});

  @override
  void paint(
    PaintingContext context,
    Offset offset, {
    @required RenderBox parentBox,
    @required SliderThemeData sliderTheme,
    @required Animation<double> enableAnimation,
    @required TextDirection textDirection,
    @required Offset thumbCenter,
    bool isDiscrete = false,
    bool isEnabled = false,
    double additionalActiveTrackHeight = 2,
  }) {
    assert(context != null);
    assert(offset != null);
    assert(parentBox != null);
    assert(sliderTheme != null);
    assert(sliderTheme.disabledActiveTrackColor != null);
    assert(sliderTheme.disabledInactiveTrackColor != null);
    assert(sliderTheme.activeTrackColor != null);
    assert(sliderTheme.inactiveTrackColor != null);
    assert(sliderTheme.thumbShape != null);
    assert(enableAnimation != null);
    assert(textDirection != null);
    assert(thumbCenter != null);
    // If the slider [SliderThemeData.trackHeight] is less than or equal to 0,
    // then it makes no difference whether the track is painted or not,
    // therefore the painting  can be a no-op.
    if (sliderTheme.trackHeight <= 0) {
      return;
    }

    final Rect trackRect = getPreferredRect(
      parentBox: parentBox,
      offset: offset,
      sliderTheme: sliderTheme,
      isEnabled: isEnabled,
      isDiscrete: isDiscrete,
    );

    // Assign the track segment paints, which are leading: active and
    // trailing: inactive.
    final ColorTween activeTrackColorTween = ColorTween(begin: sliderTheme.disabledActiveTrackColor, end: sliderTheme.activeTrackColor);
    final ColorTween inactiveTrackColorTween = darkenInactive
      ? ColorTween(begin: sliderTheme.disabledInactiveTrackColor, end: sliderTheme.inactiveTrackColor) 
      : activeTrackColorTween;
    final Paint activePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = activeTrackColorTween.evaluate(enableAnimation);
    final Paint inactivePaint = Paint()
      ..shader = gradient.createShader(trackRect)
      ..color = inactiveTrackColorTween.evaluate(enableAnimation);
    Paint leftTrackPaint;
    Paint rightTrackPaint;
    switch (textDirection) {
      case TextDirection.ltr:
        leftTrackPaint = activePaint;
        rightTrackPaint = inactivePaint;
        break;
      case TextDirection.rtl:
        leftTrackPaint = inactivePaint;
        rightTrackPaint = activePaint;
        break;
    }
    final Radius trackRadius = Radius.circular(trackRect.height / 2);
    final Radius activeTrackRadius = Radius.circular(trackRect.height / 2 + 1);

    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        trackRect.left,
        (textDirection == TextDirection.ltr) ? trackRect.top - (additionalActiveTrackHeight / 2): trackRect.top,
        thumbCenter.dx,
        (textDirection == TextDirection.ltr) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius : trackRadius,
        bottomLeft: (textDirection == TextDirection.ltr) ? activeTrackRadius: trackRadius,
      ),
      leftTrackPaint,
    );
    context.canvas.drawRRect(
      RRect.fromLTRBAndCorners(
        thumbCenter.dx,
        (textDirection == TextDirection.rtl) ? trackRect.top - (additionalActiveTrackHeight / 2) : trackRect.top,
        trackRect.right,
        (textDirection == TextDirection.rtl) ? trackRect.bottom + (additionalActiveTrackHeight / 2) : trackRect.bottom,
        topRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
        bottomRight: (textDirection == TextDirection.rtl) ? activeTrackRadius : trackRadius,
      ),
      rightTrackPaint,
    );
  }
}

导入“包装：颤振/材料.省道”；
类GradientRectSliderTrackShape使用BaseSliderTrackShape扩展了SliderTrackShape{
///基于https://www.youtube.com/watch?v=Wl4F5V6BoJw
///创建一个滑块轨迹，用于绘制两个外边缘为圆形的矩形。
最终线性梯度；
最终bool变暗激活；
const gradientrectlidertrackshape（{this.gradient:const LinearGradient（colors:[colors.lightBlue，colors.blue]），this.darkininactive:true}）；
@凌驾
空漆(
绘画语境，
抵消{
@必需的RenderBox父框，
@所需幻灯片主题数据幻灯片主题，
@所需的动画启用，
@所需文本方向文本方向，
@所需偏移拇指中心，
bool isDiscrete=false，
bool isEnabled=false，
双重附加ActiveTrackHeight=2，
}) {
断言（上下文！=null）；
断言（偏移量！=null）；
断言（parentBox！=null）；
断言（sliderTheme！=null）；
断言（sliderTheme.disabledActiveTrackColor！=null）；
断言（sliderTheme.disabledInactiveTrackColor！=null）；
断言（sliderTheme.activeTrackColor！=null）；
断言（sliderTheme.inactiveTrackColor！=null）；
断言（sliderTheme.thumbShape！=null）；
断言（enableAnimation！=null）；
断言（textDirection！=null）；
断言（thumbCenter！=null）；
//如果滑块[SliderThemeData.trackHeight]小于或等于0，
//那么轨道是否上漆也没什么区别，
//因此，这幅画可以是禁止使用的。
如果（sliderTheme.trackHeight使用这个库，它很容易实现


使用这个库。它很容易实现


您所说的
”是什么意思，但没有“SliderTheme”
？例如，在文本小部件中，您可以添加样式（TextTheme）更改大小、颜色和字体。-如果您没有安装本地API文档，您可以随时检查-它们在右上角有漂亮的
Search API docs
Search字段，但是如何添加渐变？只有颜色属性，没有绘画（文本小部件）或者渐变属性。检查
*Shape
属性你所说的
'是什么意思，但是没有“SliderTheme”
？例如，在文本小部件中，你可以添加样式（TextTheme）更改大小、颜色和字体。-如果您没有安装本地API文档，您可以随时检查-它们在右上角有漂亮的
搜索API文档
搜索字段，但是如何添加渐变？只有颜色属性，没有绘画（文本小部件）或渐变属性。检查
*形状
属性