84 lines
2.4 KiB
Dart
84 lines
2.4 KiB
Dart
// 自定义固定宽度指示器（带圆角），支持渐变色
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import 'package:flutter/cupertino.dart';
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class ATFixedWidthTabIndicator extends Decoration {
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final double width;
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final Color? color; // 改为可选参数
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final Gradient? gradient; // 新增渐变参数
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final double height;
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final double borderRadius;
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const ATFixedWidthTabIndicator({
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required this.width,
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this.color, // 颜色和渐变至少提供一个
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this.gradient,
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this.height = 3.0,
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this.borderRadius = 2.0,
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}) : assert(color != null || gradient != null,
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'必须提供color或gradient参数');
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@override
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BoxPainter createBoxPainter([VoidCallback? onChanged]) {
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return _FixedWidthTabIndicatorPainter(
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width: width,
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color: color,
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gradient: gradient,
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height: height,
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borderRadius: borderRadius,
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onChange: onChanged,
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);
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}
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}
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class _FixedWidthTabIndicatorPainter extends BoxPainter {
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final double width;
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final Color? color;
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final Gradient? gradient;
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final double height;
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final double borderRadius;
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_FixedWidthTabIndicatorPainter({
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required this.width,
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required this.color,
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required this.gradient,
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required this.height,
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required this.borderRadius,
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VoidCallback? onChange,
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}) : assert(color != null || gradient != null),
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super(onChange);
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@override
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void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
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final Paint paint = Paint()..style = PaintingStyle.fill;
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// 设置颜色或渐变
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if (gradient != null) {
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final Rect rect = offset & configuration.size!;
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final double left = rect.left + (rect.width - width) / 2;
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final double top = rect.bottom - height;
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final Rect indicatorRect = Rect.fromLTWH(left, top, width, height);
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// 创建渐变着色器
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paint.shader = gradient!.createShader(indicatorRect);
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} else {
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paint.color = color!;
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}
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final Rect rect = offset & configuration.size!;
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// 计算固定宽度的指示器位置（居中）
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final double left = rect.left + (rect.width - width) / 2;
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final double top = rect.bottom - height;
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final Rect indicatorRect = Rect.fromLTWH(left, top, width, height);
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// 创建圆角矩形
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final RRect roundedRect = RRect.fromRectAndRadius(
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indicatorRect,
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Radius.circular(borderRadius),
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);
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// 绘制圆角矩形
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canvas.drawRRect(roundedRect, paint);
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}
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} |