fis_lib_measure/lib/view/gesture/positioned_cursor.dart

import 'package:fis_common/event/event_type.dart';
import 'package:fis_measure/values/colors.dart';
import 'package:fis_measure/view/cursor.dart';
import 'package:fis_measure/view/gesture/cross_position_indicator.dart';
import 'package:flutter/material.dart';
import 'package:get/get.dart';

abstract class IMouseState {
  Offset? get mousePosition;
  set mousePosition(Offset? value);

  Offset? get cursorPosition;

  MeasureCursorType get cursorType;
  set cursorType(MeasureCursorType value);

  double get cursorSize;
  set cursorSize(double value);

  /// 卡尺缩放比
  double get cursorScaleRatio;
  set cursorScaleRatio(double value);

  late FEventHandler<Offset?> mousePositionChanged;
  late FEventHandler<MeasureCursorType> cursorTypeChanged;
  late FEventHandler<double> cursorSizeChanged;
  late FEventHandler<double> cursorScaleRatioChanged;
  late FEventHandler<CrossIndicatorStyle> crossIndicatorStyleChanged;
}

class MouseState implements IMouseState {
  Offset? _mousePosition;
  double _cursorSize = 16;
  double _cursorScaleRatio = 1;
  MeasureCursorType _cursorType = MeasureCursorType.cursor01;

  @override
  var mousePositionChanged = FEventHandler<Offset?>();

  @override
  var cursorSizeChanged = FEventHandler<double>();
  @override
  var cursorScaleRatioChanged = FEventHandler<double>();

  @override
  var cursorTypeChanged = FEventHandler<MeasureCursorType>();

  @override
  var crossIndicatorStyleChanged = FEventHandler<CrossIndicatorStyle>();

  @override
  Offset? get mousePosition => _mousePosition;
  @override
  set mousePosition(Offset? value) {
    if (value != _mousePosition) {
      _mousePosition = value;
      mousePositionChanged.emit(this, value);
    }
  }

  @override
  double get cursorSize => _cursorSize;
  @override
  set cursorSize(double value) {
    if (value != _cursorSize) {
      _cursorSize = value;
      cursorSizeChanged.emit(this, value);
    }
  }

  @override
  double get cursorScaleRatio => _cursorScaleRatio;
  @override
  set cursorScaleRatio(double value) {
    if (value != _cursorScaleRatio) {
      _cursorScaleRatio = value;
      cursorScaleRatioChanged.emit(this, value);
    }
  }

  @override
  MeasureCursorType get cursorType => _cursorType;
  @override
  set cursorType(MeasureCursorType value) {
    if (value != _cursorType) {
      _cursorType = value;
      cursorTypeChanged.emit(this, value);
    }
  }

  @override
  Offset? get cursorPosition {
    if (mousePosition == null) return null;

    double dx = mousePosition!.dx, dy = mousePosition!.dy;
    final offset = cursorScaleRatio * cursorSize / 2;
    dx -= offset;
    dy -= offset;
    return Offset(dx, dy);
  }
}

class PositionedCursor extends StatefulWidget {
  const PositionedCursor({Key? key}) : super(key: key);

  @override
  State<StatefulWidget> createState() => _PositionedCursorState();
}

class _PositionedCursorState extends State<PositionedCursor> {
  final mouseState = Get.find<IMouseState>();

  @override
  void initState() {
    mouseState.cursorSizeChanged.addListener(onCursorSizeChanged);
    mouseState.cursorScaleRatioChanged.addListener(onCursorScaleRatioChanged);
    mouseState.cursorTypeChanged.addListener(cursorTypeChanged);
    mouseState.mousePositionChanged.addListener(mousePositionChanged);
    super.initState();
  }

  @override
  void dispose() {
    mouseState.cursorSizeChanged.removeListener(onCursorSizeChanged);
    mouseState.cursorScaleRatioChanged
        .removeListener(onCursorScaleRatioChanged);
    mouseState.cursorTypeChanged.removeListener(cursorTypeChanged);
    mouseState.mousePositionChanged.removeListener(mousePositionChanged);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final position = mouseState.cursorPosition;
    if (position == null) return Container();

    return Positioned(
      left: position.dx,
      top: position.dy,
      child: MeasureCursor(
        type: mouseState.cursorType,
        size: mouseState.cursorSize * mouseState.cursorScaleRatio,
        color: MeasureColors.Primary,
      ),
    );
  }

  void onCursorSizeChanged(Object sender, dynamic e) {
    onUpdate();
  }

  void onCursorScaleRatioChanged(Object sender, dynamic e) {
    onUpdate();
  }

  void cursorTypeChanged(Object sender, dynamic e) {
    onUpdate();
  }

  void mousePositionChanged(Object sender, dynamic e) {
    onUpdate();
  }

  void onUpdate() {
    setState(() {});
  }
}