SliderTheme(
              data: SliderThemeData(
              disabledActiveTrackColor: Colors.blue,
              disabledInactiveTrackColor: Colors.black12,
              trackHeight: 3,
              thumbShape: RoundSliderThumbShape(enabledThumbRadius: 0.0),
              trackShape: RoundSliderTrackShape(),
            ),
            child: Slider(
              value: 10,
              onChanged: null,
              min: 0,
              max: 100,
            ),
 ),

class RoundSliderTrackShape extends SliderTrackShape {
  const RoundSliderTrackShape(
      {this.disabledThumbGapWidth = 0, this.radius = 0});

  final double disabledThumbGapWidth;
  final double radius;

  @override
  Rect getPreferredRect({
    RenderBox parentBox,
    Offset offset = Offset.zero,
    SliderThemeData sliderTheme,
    bool isEnabled,
    bool isDiscrete,
  }) {
    final double overlayWidth =
        sliderTheme.overlayShape.getPreferredSize(isEnabled, isDiscrete).width;
    final double trackHeight = sliderTheme.trackHeight;
    assert(overlayWidth >= 0);
    assert(trackHeight >= 0);
    assert(parentBox.size.width >= overlayWidth);
    assert(parentBox.size.height >= trackHeight);

    final double trackLeft = offset.dx;
    final double trackTop =
        offset.dy + (parentBox.size.height - trackHeight) / 2;

    final double trackWidth = parentBox.size.width;
    return Rect.fromLTWH(trackLeft, trackTop, trackWidth, trackHeight);
  }

  @override
  void paint(
    PaintingContext context,
    Offset offset, {
    RenderBox parentBox,
    SliderThemeData sliderTheme,
    Animation<double> enableAnimation,
    TextDirection textDirection,
    Offset thumbCenter,
    bool isDiscrete,
    bool isEnabled,
  }) {
    if (sliderTheme.trackHeight == 0) {
      return;
    }

    final ColorTween activeTrackColorTween = ColorTween(
        begin: sliderTheme.disabledActiveTrackColor,
        end: sliderTheme.activeTrackColor);
    final ColorTween inactiveTrackColorTween = ColorTween(
        begin: sliderTheme.disabledInactiveTrackColor,
        end: sliderTheme.inactiveTrackColor);
    final Paint activePaint = Paint()
      ..color = activeTrackColorTween.evaluate(enableAnimation);
    final Paint inactivePaint = Paint()
      ..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;
    }

    double horizontalAdjustment = 0.0;
    if (!isEnabled) {
      final double disabledThumbRadius =
          sliderTheme.thumbShape.getPreferredSize(false, isDiscrete).width /
              2.0;
      final double gap = disabledThumbGapWidth * (1.0 - enableAnimation.value);
      horizontalAdjustment = disabledThumbRadius + gap;
    }

    final Rect trackRect = getPreferredRect(
      parentBox: parentBox,
      offset: offset,
      sliderTheme: sliderTheme,
      isEnabled: isEnabled,
      isDiscrete: isDiscrete,
    );
    //Modify this side
    final RRect leftTrackSegment = RRect.fromLTRBR(
        trackRect.left,
        trackRect.top,
        thumbCenter.dx - horizontalAdjustment,
        trackRect.bottom,
        Radius.circular(radius));
    context.canvas.drawRRect(leftTrackSegment, leftTrackPaint);
    final RRect rightTrackSegment = RRect.fromLTRBR(
        thumbCenter.dx + horizontalAdjustment,
        trackRect.top,
        trackRect.right,
        trackRect.bottom,
        Radius.circular(radius));
    context.canvas.drawRRect(rightTrackSegment, rightTrackPaint);
  }
}