MeasureCursor

lib/components/cursor.dart

@@ -0,0 +1,170 @@
+import 'package:flutter/material.dart';
+
+enum MeasureCursorType {
+  cursor01,
+  cursor02,
+  cursor03,
+  cursor04,
+  cursor05,
+}
+
+class MeasureCursor extends StatelessWidget {
+  const MeasureCursor({
+    Key? key,
+    required this.type,
+    required this.size,
+  }) : super(key: key);
+
+  final double size;
+
+  final MeasureCursorType type;
+
+  @override
+  Widget build(BuildContext context) {
+    return SizedBox(
+      width: size,
+      height: size,
+      child: RepaintBoundary(
+        child: CustomPaint(painter: _CursorPainter(type)),
+      ),
+    );
+  }
+}
+
+class _CursorPainter extends CustomPainter {
+  const _CursorPainter(this.type);
+
+  final MeasureCursorType type;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final double width = size.width;
+    final double offset = width / 2;
+    // position center point
+    canvas.translate(offset, offset);
+
+    _CursorPathGeometry(
+      cursorType: type,
+      offset: offset,
+    ).draw(canvas);
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) {
+    return false;
+  }
+}
+
+class _CursorPathGeometry {
+  _CursorPathGeometry({
+    required double offset,
+    required this.cursorType,
+  }) {
+    _offset = offset;
+    _assemblePathArray();
+  }
+
+  // ignore: constant_identifier_names
+  static const double LINE_RATIO = 0.8;
+
+  static final Paint _paint = Paint()
+    ..color = const Color.fromARGB(255, 255, 255, 0)
+    ..strokeWidth = 2
+    ..style = PaintingStyle.stroke;
+
+  late double _offset;
+
+  final MeasureCursorType cursorType;
+
+  final List<Path> _pathArray = <Path>[];
+
+  List<Path> get pathArray => _pathArray;
+
+  void draw(Canvas canvas) {
+    canvas.save();
+    for (final Path path in _pathArray) {
+      canvas.drawPath(path, _paint);
+    }
+    canvas.restore();
+  }
+
+  void _assemblePathArray() {
+    switch (cursorType) {
+      case MeasureCursorType.cursor01:
+        _pathArray.add(_buildHorizontalLine());
+        _pathArray.add(_buildVerticalLine());
+        break;
+      case MeasureCursorType.cursor02:
+        _pathArray.add(_buildLeftBias());
+        _pathArray.add(_buildRightBias());
+        break;
+      case MeasureCursorType.cursor03:
+        _pathArray.add(_buildHorizontalLine());
+        _pathArray.add(_buildLeftBias());
+        _pathArray.add(_buildRightBias());
+        break;
+      case MeasureCursorType.cursor04:
+        _pathArray.add(_buildVerticalLine());
+        _pathArray.add(_buildLeftBias());
+        _pathArray.add(_buildRightBias());
+        break;
+      case MeasureCursorType.cursor05:
+        _pathArray.add(_buildLeftSide());
+        _pathArray.add(_buildRightSide());
+        _pathArray.add(_buildTopSide());
+        _pathArray.add(_buildBottomSide());
+        _offset *= LINE_RATIO;
+        _pathArray.add(_buildHorizontalLine());
+        _pathArray.add(_buildVerticalLine());
+        break;
+    }
+  }
+
+  Path _buildHorizontalLine() {
+    return Path()
+      ..moveTo(-_offset, 0)
+      ..lineTo(_offset, 0);
+  }
+
+  Path _buildVerticalLine() {
+    return Path()
+      ..moveTo(0, -_offset)
+      ..lineTo(0, _offset);
+  }
+
+  Path _buildLeftBias() {
+    return Path()
+      ..moveTo(-_offset, -_offset)
+      ..lineTo(_offset, _offset);
+  }
+
+  Path _buildRightBias() {
+    return Path()
+      ..moveTo(_offset, -_offset)
+      ..lineTo(-_offset, _offset);
+  }
+
+  Path _buildLeftSide() {
+    return Path()
+      ..moveTo(-_offset, -_offset * LINE_RATIO)
+      ..lineTo(-_offset, _offset * LINE_RATIO);
+  }
+
+  Path _buildRightSide() {
+    return Path()
+      ..moveTo(_offset, -_offset * LINE_RATIO)
+      ..lineTo(_offset, _offset * LINE_RATIO);
+  }
+
+  Path _buildTopSide() {
+    return Path()
+      ..moveTo(-_offset * LINE_RATIO, -_offset)
+      ..lineTo(_offset * LINE_RATIO, -_offset);
+  }
+
+  Path _buildBottomSide() {
+    return Path()
+      ..moveTo(-_offset * LINE_RATIO, _offset)
+      ..lineTo(_offset * LINE_RATIO, _offset);
+  }
+}