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ansu_ui/lib/bar/as_tab_indicator.dart

85 lines
2.5 KiB

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