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85 lines
2.5 KiB
85 lines
2.5 KiB
import 'package:flutter/material.dart';
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///渐变indicator
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///
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///fork from TabIndicator
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///
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///仅仅在发现页面中使用
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class ASTabIndicator extends Decoration {
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const ASTabIndicator({
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this.borderSide = const BorderSide(width: 4.0, color: Colors.white),
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this.insets = EdgeInsets.zero,
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}) : assert(borderSide != null),
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assert(insets != null);
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final BorderSide borderSide;
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final EdgeInsetsGeometry insets;
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@override
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Decoration lerpFrom(Decoration a, double t) {
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if (a is ASTabIndicator) {
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return ASTabIndicator(
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borderSide: BorderSide.lerp(a.borderSide, borderSide, t),
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insets: EdgeInsetsGeometry.lerp(a.insets, insets, t),
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);
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}
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return super.lerpFrom(a, t);
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}
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@override
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Decoration lerpTo(Decoration b, double t) {
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if (b is ASTabIndicator) {
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return ASTabIndicator(
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borderSide: BorderSide.lerp(borderSide, b.borderSide, t),
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insets: EdgeInsetsGeometry.lerp(insets, b.insets, t),
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);
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}
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return super.lerpTo(b, t);
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}
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@override
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_UnderlinePainter createBoxPainter([VoidCallback onChanged]) {
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return _UnderlinePainter(this, onChanged);
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}
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}
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class _UnderlinePainter extends BoxPainter {
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_UnderlinePainter(this.decoration, VoidCallback onChanged)
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: assert(decoration != null),
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super(onChanged);
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final ASTabIndicator decoration;
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BorderSide get borderSide => decoration.borderSide;
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EdgeInsetsGeometry get insets => decoration.insets;
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Rect _indicatorRectFor(Rect rect, TextDirection textDirection) {
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assert(rect != null);
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assert(textDirection != null);
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final Rect indicator = insets.resolve(textDirection).deflateRect(rect);
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return Rect.fromLTWH(
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indicator.left,
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indicator.bottom - borderSide.width,
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indicator.width,
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borderSide.width,
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);
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}
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@override
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void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
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assert(configuration != null);
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assert(configuration.size != null);
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final Rect rect = offset & configuration.size;
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final TextDirection textDirection = configuration.textDirection;
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final Rect indicator =
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_indicatorRectFor(rect, textDirection).deflate(borderSide.width / 2.0);
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final Paint paint = borderSide.toPaint()
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..strokeCap = StrokeCap.square
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..shader = LinearGradient(colors: [
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Color(0xFFE50112),
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Color(0xFFFFB1B1),
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]).createShader(rect);
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canvas.drawLine(indicator.bottomLeft, indicator.bottomRight, paint);
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}
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}
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