(flutter) add experimental GestureHandler widget and decouple from ThermionGestureDetectorDesktop

thermion_flutter/thermion_flutter/lib/thermion/widgets/camera/gestures/thermion_gesture_handler.dart

@@ -0,0 +1,193 @@
+import 'dart:async';
+
+import 'package:flutter/gestures.dart';
+import 'package:flutter/services.dart';
+import 'package:logging/logging.dart';
+import 'package:thermion_dart/thermion_dart/entities/abstract_gizmo.dart';
+import 'package:thermion_dart/thermion_dart/thermion_viewer.dart';
+
+enum ThermionGestureState {
+  NULL,
+  ENTITY_HIGHLIGHTED,
+  GIZMO_ATTACHED,
+  ROTATING,
+  PANNING,
+}
+
+class ThermionGestureHandler {
+  final ThermionViewer viewer;
+  final bool enableCamera;
+  final bool enablePicking;
+  final Logger _logger = Logger("ThermionGestureHandler");
+
+  ThermionGestureState _currentState = ThermionGestureState.NULL;
+  AbstractGizmo? _gizmo;
+  Timer? _scrollTimer;
+  ThermionEntity? _highlightedEntity;
+  StreamSubscription<FilamentPickResult>? _pickResultSubscription;
+
+  ThermionGestureHandler({
+    required this.viewer,
+    this.enableCamera = true,
+    this.enablePicking = true,
+  }) {
+    try {
+      _gizmo = viewer.gizmo;
+    } catch (err) {
+      _logger.warning(
+          "Failed to get gizmo. If you are running on WASM, this is expected");
+    }
+
+    _pickResultSubscription = viewer.pickResult.listen(_onPickResult);
+
+    // Add keyboard listener
+    RawKeyboard.instance.addListener(_handleKeyEvent);
+  }
+
+  void _handleKeyEvent(RawKeyEvent event) {
+    if (event is RawKeyDownEvent &&
+        event.logicalKey == LogicalKeyboardKey.escape) {
+      _resetToNullState();
+    }
+  }
+
+  void _resetToNullState() async {
+    // set current state to NULL first, so that any subsequent pointer movements
+    // won't attempt to translate a deleted entity
+    _currentState = ThermionGestureState.NULL;
+    if (_highlightedEntity != null) {
+      await viewer.removeStencilHighlight(_highlightedEntity!);
+      _highlightedEntity = null;
+    }
+  }
+
+  void _onPickResult(FilamentPickResult result) async {
+    var targetEntity = await viewer.getAncestor(result.entity) ?? result.entity;
+
+    if (_highlightedEntity != targetEntity) {
+      if (_highlightedEntity != null) {
+        await viewer.removeStencilHighlight(_highlightedEntity!);
+      }
+
+      _highlightedEntity = targetEntity;
+      if (_highlightedEntity != null) {
+        await viewer.setStencilHighlight(_highlightedEntity!);
+      }
+
+      _currentState = _highlightedEntity != null
+          ? ThermionGestureState.ENTITY_HIGHLIGHTED
+          : ThermionGestureState.NULL;
+    }
+  }
+
+  Future<void> onPointerHover(Offset localPosition) async {
+    if (_currentState == ThermionGestureState.GIZMO_ATTACHED) {
+      _gizmo?.checkHover(localPosition.dx, localPosition.dy);
+    }
+
+    // Update highlighted entity position
+    if (_highlightedEntity != null) {
+      await viewer.queuePositionUpdateFromViewportCoords(
+        _highlightedEntity!,
+        localPosition.dx,
+        localPosition.dy,
+      );
+    }
+  }
+
+  Future<void> onPointerScroll(Offset localPosition, double scrollDelta) async {
+    if (_currentState == ThermionGestureState.NULL && enableCamera) {
+      await _zoom(localPosition, scrollDelta);
+    }
+  }
+
+  Future<void> onPointerDown(Offset localPosition, int buttons) async {
+    if (_currentState == ThermionGestureState.ENTITY_HIGHLIGHTED) {
+      _resetToNullState();
+      return;
+    }
+
+    if (enablePicking && buttons != kMiddleMouseButton) {
+      viewer.pick(localPosition.dx.toInt(), localPosition.dy.toInt());
+    }
+
+    if (buttons == kMiddleMouseButton && enableCamera) {
+      await viewer.rotateStart(localPosition.dx, localPosition.dy);
+      _currentState = ThermionGestureState.ROTATING;
+    } else if (buttons == kPrimaryMouseButton && enableCamera) {
+      await viewer.panStart(localPosition.dx, localPosition.dy);
+      _currentState = ThermionGestureState.PANNING;
+    }
+  }
+
+  Future<void> onPointerMove(
+      Offset localPosition, Offset delta, int buttons) async {
+    switch (_currentState) {
+      case ThermionGestureState.NULL:
+        // This case should not occur now, as we set the state on pointer down
+        break;
+      case ThermionGestureState.ENTITY_HIGHLIGHTED:
+        await _handleEntityHighlightedMove(localPosition);
+        break;
+      case ThermionGestureState.GIZMO_ATTACHED:
+        // Do nothing
+        break;
+      case ThermionGestureState.ROTATING:
+        if (enableCamera) {
+          await viewer.rotateUpdate(localPosition.dx, localPosition.dy);
+        }
+        break;
+      case ThermionGestureState.PANNING:
+        if (enableCamera) {
+          await viewer.panUpdate(localPosition.dx, localPosition.dy);
+        }
+        break;
+    }
+  }
+
+  Future<void> onPointerUp(int buttons) async {
+    switch (_currentState) {
+      case ThermionGestureState.ROTATING:
+        await viewer.rotateEnd();
+        _currentState = ThermionGestureState.NULL;
+        break;
+      case ThermionGestureState.PANNING:
+        await viewer.panEnd();
+        _currentState = ThermionGestureState.NULL;
+        break;
+      default:
+        // For other states, no action needed
+        break;
+    }
+  }
+
+  Future<void> _handleEntityHighlightedMove(Offset localPosition) async {
+    if (_highlightedEntity != null) {
+      await viewer.queuePositionUpdateFromViewportCoords(
+        _highlightedEntity!,
+        localPosition.dx,
+        localPosition.dy,
+      );
+    }
+  }
+
+  Future<void> _zoom(Offset localPosition, double scrollDelta) async {
+    _scrollTimer?.cancel();
+    await viewer.zoomBegin();
+    await viewer.zoomUpdate(
+        localPosition.dx, localPosition.dy, scrollDelta > 0 ? 1 : -1);
+
+    _scrollTimer = Timer(const Duration(milliseconds: 100), () async {
+      await viewer.zoomEnd();
+    });
+  }
+
+  void dispose() {
+    _pickResultSubscription?.cancel();
+    if (_highlightedEntity != null) {
+      viewer.removeStencilHighlight(_highlightedEntity!);
+    }
+    // Remove keyboard listener
+    RawKeyboard.instance.removeListener(_handleKeyEvent);
+  }
+}