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packages/idraw/lib/components/coordinate.dart

@@ -0,0 +1,84 @@
+import 'package:flutter/material.dart';
+
+/// create by 张风捷特烈 on 2020/5/1
+/// contact me by email 1981462002@qq.com
+/// 说明:
+@immutable
+class Coordinate {
+  final double step;
+  final double strokeWidth;
+  final Color axisColor;
+  final Color gridColor;
+
+  Coordinate(
+      {this.step = 20,
+        this.strokeWidth = .5,
+        this.axisColor = Colors.blue,
+        this.gridColor = Colors.grey});
+
+  final Paint _gridPaint = Paint();
+
+  void paint(Canvas canvas, Size size) {
+    canvas.save();
+    canvas.translate(size.width / 2, size.height / 2);
+    _drawGrid(canvas, size);
+    _drawAxis(canvas, size);
+    canvas.restore();
+  }
+
+  void _drawGrid(Canvas canvas, Size size) {
+    _gridPaint
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = .5
+      ..color = Colors.grey;
+    _drawBottomRight(canvas, size);
+    canvas.save();
+    canvas.scale(1, -1); //沿x轴镜像
+    _drawBottomRight(canvas, size);
+    canvas.restore();
+
+    canvas.save();
+    canvas.scale(-1, 1); //沿y轴镜像
+    _drawBottomRight(canvas, size);
+    canvas.restore();
+
+    canvas.save();
+    canvas.scale(-1, -1); //沿原点镜像
+    _drawBottomRight(canvas, size);
+    canvas.restore();
+  }
+
+  void _drawAxis(Canvas canvas, Size size) {
+    _gridPaint
+      ..color = Colors.blue
+      ..strokeWidth = 1.5;
+    canvas.drawLine(
+        Offset(-size.width / 2, 0), Offset(size.width / 2, 0), _gridPaint);
+    canvas.drawLine(
+        Offset(0, -size.height / 2), Offset(0, size.height / 2), _gridPaint);
+    canvas.drawLine(Offset(0, size.height / 2),
+        Offset(0 - 7.0, size.height / 2 - 10), _gridPaint);
+    canvas.drawLine(Offset(0, size.height / 2),
+        Offset(0 + 7.0, size.height / 2 - 10), _gridPaint);
+    canvas.drawLine(
+        Offset(size.width / 2, 0), Offset(size.width / 2 - 10, 7), _gridPaint);
+    canvas.drawLine(
+        Offset(size.width / 2, 0), Offset(size.width / 2 - 10, -7), _gridPaint);
+  }
+
+  void _drawBottomRight(Canvas canvas, Size size) {
+    canvas.save();
+    for (int i = 0; i < size.height / 2 / step; i++) {
+      canvas.drawLine(Offset(0, 0), Offset(size.width / 2, 0), _gridPaint);
+      canvas.translate(0, step);
+    }
+    canvas.restore();
+
+    canvas.save();
+    for (int i = 0; i < size.width / 2 / step; i++) {
+      canvas.drawLine(Offset(0, 0), Offset(0, size.height / 2), _gridPaint);
+      canvas.translate(step , 0);
+    }
+    canvas.restore();
+  }
+}