AiKeyboard2025/lib/widget/gradient_rect_slider_track_shape.dart

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';

/// 自定义带有渐变的 Slider 轨道
class GradientRectSliderTrackShape extends SliderTrackShape {
  const GradientRectSliderTrackShape();

  @override
  Rect getPreferredRect({
    required RenderBox parentBox,
    Offset offset = Offset.zero,
    required SliderThemeData sliderTheme,
    bool isEnabled = false,
    bool isDiscrete = false,
  }) {
    final double trackHeight = sliderTheme.trackHeight ?? 4;
    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, {
        required RenderBox parentBox,
        required SliderThemeData sliderTheme,
        required Animation<double> enableAnimation,
        required TextDirection textDirection,
        required Offset thumbCenter,
        bool isDiscrete = false,
        bool isEnabled = false,
        Offset? secondaryOffset,
        double additionalActiveTrackHeight = 0,
      }) {
    // 轨道矩形区域
    final Rect trackRect = getPreferredRect(
      parentBox: parentBox,
      offset: offset,
      sliderTheme: sliderTheme,
      isEnabled: isEnabled,
      isDiscrete: isDiscrete,
    );

    // 激活部分的宽度
    final activeRect = Rect.fromLTRB(
      trackRect.left,
      trackRect.top,
      thumbCenter.dx,
      trackRect.bottom,
    );

    // 非激活部分的宽度
    final inactiveRect = Rect.fromLTRB(
      thumbCenter.dx,
      trackRect.top,
      trackRect.right,
      trackRect.bottom,
    );

    final Canvas canvas = context.canvas;

    // 绘制激活部分（渐变）
    final activePaint = Paint()..shader = const LinearGradient(
      begin: Alignment(0.04, 0.21),
      end: Alignment(0.98, 0.76),
      colors: [Color(0xFFD5BAF8),Color(0xFFAA88FA) ],
    ).createShader(activeRect);

    // 绘制非激活部分
    final inactivePaint = Paint()
      ..color = sliderTheme.inactiveTrackColor ?? Colors.grey.shade200;

    // 圆角半径
    final radius = Radius.circular(trackRect.height / 2);

    // 绘制轨道
    canvas.drawRRect(
      RRect.fromRectAndRadius(inactiveRect, radius),
      inactivePaint,
    );
    canvas.drawRRect(
      RRect.fromRectAndRadius(activeRect, radius),
      activePaint,
    );
  }
}