books

packages/idraw/lib/p16/s02.dart

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+import 'dart:math';
+
+// import 'dart:ui' as ui;
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+
+/// create by 张风捷特烈 on 2020/11/5
+/// contact me by email 1981462002@qq.com
+/// 说明:
+class Paper extends StatelessWidget {
+  const Paper({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      color: Colors.white,
+      alignment: Alignment.center,
+      child: const ICharts(),
+    );
+  }
+}
+
+class ICharts extends StatefulWidget {
+  const ICharts({super.key});
+
+  @override
+  _IChartsState createState() => _IChartsState();
+}
+
+class _IChartsState extends State<ICharts> with SingleTickerProviderStateMixin{
+
+  late AnimationController _controller;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(
+      duration: const Duration(milliseconds: 800),
+      vsync: this,
+    )..forward();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(alignment: Alignment.topCenter, children: [
+      Container(
+        width: 350,
+        height: 250,
+        padding: EdgeInsets.only(top: 40, right: 20, bottom: 20, left: 20),
+        child: CustomPaint(
+          painter: ChartPainter(repaint: _controller),
+        ),
+      ),
+      Padding(
+        padding: const EdgeInsets.only(top:8.0),
+        child: Text(
+          "捷特数学成绩统计图 - 2040 年",
+          style: TextStyle(fontSize: 12, fontWeight: FontWeight.bold),
+        ),
+      )
+    ]);
+  }
+}
+
+const double _kScaleHeight = 8; // 刻度高
+const double _kBarPadding = 10; // 柱状图前间隔
+
+class ChartPainter extends CustomPainter {
+  final TextPainter _textPainter =
+  TextPainter(textDirection: TextDirection.ltr);
+
+  final List<double> yData = [88, 98, 70, 80, 100, 75];
+  final List<String> xData = ["7月", "8月", "9月", "10月", "11月", "12月"];
+
+  // final List<String> xData = [ "语文","数学", "英语", "物理", "化学", "生物"];
+
+  final Animation<double> repaint;
+
+
+  Path axisPath = Path();
+  Paint axisPaint = Paint()
+    ..style = PaintingStyle.stroke
+    ..strokeWidth = 1;
+
+  Paint gridPaint = Paint()
+    ..style = PaintingStyle.stroke
+    ..color = Colors.grey
+    ..strokeWidth = 0.5;
+  Paint fillPaint = Paint()..color = Colors.red;
+
+  double xStep = 0; // x 间隔
+  double yStep = 0; // y 间隔
+
+  double maxData = 0; // 数据最大值
+
+  ChartPainter({required this.repaint}):super(repaint: repaint) {
+    maxData = yData.reduce(max);
+  }
+
+  @override
+  void paint(Canvas canvas, Size size) {
+
+    canvas.translate(0, size.height);
+    canvas.translate(_kScaleHeight, -_kScaleHeight);
+
+    axisPath.moveTo(-_kScaleHeight, 0);
+    axisPath.relativeLineTo(size.width, 0);
+    axisPath.moveTo(0, _kScaleHeight);
+    axisPath.relativeLineTo(0, -size.height);
+    canvas.drawPath(axisPath, axisPaint);
+
+    drawYText(canvas, size);
+    drawXText(canvas, size);
+    drawBarChart(canvas,size);
+  }
+
+  void drawXText(Canvas canvas, Size size) {
+    xStep = (size.width - _kScaleHeight) / xData.length;
+    canvas.save();
+    canvas.translate(xStep, 0);
+    for (int i = 0; i < xData.length; i++) {
+      canvas.drawLine(Offset(0, 0), Offset(0, _kScaleHeight), axisPaint);
+      _drawAxisText(canvas, xData[i],
+          alignment: Alignment.center, offset: Offset(-xStep / 2, 10));
+      canvas.translate(xStep, 0);
+    }
+    canvas.restore();
+  }
+
+  void drawBarChart(Canvas canvas, Size size) {
+    canvas.save();
+    canvas.translate(xStep, 0);
+    for (int i = 0; i < xData.length; i++) {
+      double dataHeight = -(yData[i] / maxData * (size.height - _kScaleHeight));
+      canvas.drawRect(
+          Rect.fromLTWH(
+              _kBarPadding, 0, xStep-2*_kBarPadding, dataHeight*repaint.value)
+              .translate(-xStep, 0),
+          fillPaint);
+      canvas.translate(xStep, 0);
+    }
+    canvas.restore();
+  }
+
+  void drawYText(Canvas canvas, Size size) {
+    canvas.save();
+    yStep = (size.height - _kScaleHeight) / 5;
+    double numStep = maxData / 5;
+    for (int i = 0; i <= 5; i++) {
+      if (i == 0) {
+        _drawAxisText(canvas, '0', offset: Offset(-10, 2));
+        canvas.translate(0, -yStep);
+        continue;
+      }
+
+      canvas.drawLine(
+          Offset(0, 0), Offset(size.width - _kScaleHeight, 0), gridPaint);
+
+      canvas.drawLine(Offset(-_kScaleHeight, 0), Offset(0, 0), axisPaint);
+      String str = '${(numStep * i).toStringAsFixed(0)}';
+      _drawAxisText(canvas, str, offset: Offset(-10, 2));
+      canvas.translate(0, -yStep);
+    }
+    canvas.restore();
+  }
+
+  void _drawAxisText(Canvas canvas, String str,
+      {Color color = Colors.black,
+        bool x = false,
+        Alignment alignment = Alignment.centerRight,
+        Offset offset = Offset.zero}) {
+    TextSpan text = TextSpan(
+        text: str,
+        style: TextStyle(
+          fontSize: 11,
+          color: color,
+        ));
+
+    _textPainter.text = text;
+    _textPainter.layout(); // 进行布局
+
+    Size size = _textPainter.size;
+
+    Offset offsetPos = Offset(-size.width / 2, -size.height / 2)
+        .translate(-size.width / 2 * alignment.x + offset.dx, 0.0 + offset.dy);
+    _textPainter.paint(canvas, offsetPos);
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
+}