107 lines
3.1 KiB
Dart
107 lines
3.1 KiB
Dart
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import 'dart:math' as math;
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import 'package:flutter/material.dart';
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import '../theme/theme_x.dart';
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/// A single-series trend line — currently just backup-duration history.
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/// Hand-rolled `CustomPainter` rather than a charting dependency: one chart
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/// in the whole app, a specific visual spec (faint grid, thin line,
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/// emphasized endpoint), full control for near-zero cost.
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class Sparkline extends StatelessWidget {
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const Sparkline({super.key, required this.values, this.width = 240, this.height = 52});
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final List<double> values;
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final double width;
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final double height;
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@override
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Widget build(BuildContext context) {
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return SizedBox(
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width: width,
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height: height,
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child: CustomPaint(
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painter: _SparklinePainter(
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values: values,
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lineColor: context.colors.primary,
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gridColor: context.colors.outlineVariant,
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),
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),
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);
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}
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}
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class _SparklinePainter extends CustomPainter {
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_SparklinePainter({required this.values, required this.lineColor, required this.gridColor});
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final List<double> values;
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final Color lineColor;
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final Color gridColor;
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static const _topPad = 6.0;
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static const _bottomPad = 6.0;
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@override
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void paint(Canvas canvas, Size size) {
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if (values.isEmpty) return;
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final minV = values.reduce(math.min);
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final maxV = values.reduce(math.max);
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final range = (maxV - minV).abs() < 1e-9 ? 1.0 : maxV - minV;
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final plotHeight = size.height - _topPad - _bottomPad;
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final gridPaint = Paint()
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..color = gridColor
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..strokeWidth = 1;
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canvas.drawLine(Offset(0, _topPad), Offset(size.width, _topPad), gridPaint);
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canvas.drawLine(
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Offset(0, size.height - _bottomPad),
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Offset(size.width, size.height - _bottomPad),
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gridPaint,
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);
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if (values.length == 1) {
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final y = _topPad + plotHeight / 2;
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canvas.drawCircle(Offset(size.width, y), 3.4, Paint()..color = lineColor);
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return;
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}
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final dx = size.width / (values.length - 1);
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final points = [
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for (var i = 0; i < values.length; i++)
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Offset(i * dx, _topPad + plotHeight - ((values[i] - minV) / range) * plotHeight),
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];
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final fillPath = Path()..moveTo(points.first.dx, size.height - _bottomPad);
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for (final p in points) {
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fillPath.lineTo(p.dx, p.dy);
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}
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fillPath
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..lineTo(points.last.dx, size.height - _bottomPad)
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..close();
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canvas.drawPath(fillPath, Paint()..color = lineColor.withValues(alpha: 0.14));
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final linePath = Path()..moveTo(points.first.dx, points.first.dy);
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for (final p in points.skip(1)) {
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linePath.lineTo(p.dx, p.dy);
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}
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canvas.drawPath(
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linePath,
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Paint()
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..color = lineColor
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..style = PaintingStyle.stroke
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..strokeWidth = 2
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..strokeCap = StrokeCap.round
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..strokeJoin = StrokeJoin.round,
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);
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canvas.drawCircle(points.last, 3.4, Paint()..color = lineColor);
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}
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@override
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bool shouldRepaint(covariant _SparklinePainter oldDelegate) =>
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oldDelegate.values != values ||
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oldDelegate.lineColor != lineColor ||
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oldDelegate.gridColor != gridColor;
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}
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