[two_dimensional_scrollables] Refactor Spans for common use

packages/two_dimensional_scrollables/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.1
+
+* Refactors TableSpans to use basic Span classes. Clean up for incoming TreeView.
+
 ## 0.2.0
 
 * Adds support for infinite rows and columns in TableView.

packages/two_dimensional_scrollables/lib/src/common/implementation_span.dart

@@ -0,0 +1,141 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
+
+import 'span.dart';
+
+// This file is NOT exported as part of the package.
+
+/// A contextual used by the [RenderTableViewport].
+///
+/// Used to track the layout information, and additional configurations of the
+/// span during multiple layout passes.
+abstract class ImplementedSpan
+    with Diagnosticable
+    implements HitTestTarget, MouseTrackerAnnotation {
+  /// The leading edge of the span in the viewport, orientated to the column or
+  /// row it represents.
+  double get leadingOffset => _leadingOffset;
+  late double _leadingOffset;
+
+  /// The extent of the span.
+  double get extent => _extent;
+  late double _extent;
+
+  /// The Span that was used to populate this implemented span.
+  Span get configuration => _configuration!;
+  Span? _configuration;
+
+  /// The trailing offset of the span.
+  ///
+  /// Includes any padding the span may have.
+  double get trailingOffset {
+    return leadingOffset +
+        extent +
+        configuration.padding.leading +
+        configuration.padding.trailing;
+  }
+
+  // ---- Span Management ----
+
+  /// Called to update the span as needed by [RenderTableViewport].
+  void update({
+    required Span configuration,
+    required double leadingOffset,
+    required double extent,
+  }) {
+    _leadingOffset = leadingOffset;
+    _extent = extent;
+    if (configuration == _configuration) {
+      return;
+    }
+    _configuration = configuration;
+    // Only sync recognizers if they are in use already.
+    if (_recognizers != null) {
+      _syncRecognizers();
+    }
+  }
+
+  /// Disposes of the span and its recognizers.
+  void dispose() {
+    _disposeRecognizers();
+  }
+
+  // ---- Recognizers management ----
+
+  Map<Type, GestureRecognizer>? _recognizers;
+
+  void _syncRecognizers() {
+    if (configuration.recognizerFactories.isEmpty) {
+      _disposeRecognizers();
+      return;
+    }
+    final Map<Type, GestureRecognizer> newRecognizers =
+        <Type, GestureRecognizer>{};
+    for (final Type type in configuration.recognizerFactories.keys) {
+      assert(!newRecognizers.containsKey(type));
+      newRecognizers[type] = _recognizers?.remove(type) ??
+          configuration.recognizerFactories[type]!.constructor();
+      assert(
+        newRecognizers[type].runtimeType == type,
+        'GestureRecognizerFactory of type $type created a GestureRecognizer of '
+        'type ${newRecognizers[type].runtimeType}. The '
+        'GestureRecognizerFactory must be specialized with the type of the '
+        'class that it returns from its constructor method.',
+      );
+      configuration.recognizerFactories[type]!
+          .initializer(newRecognizers[type]!);
+    }
+    _disposeRecognizers(); // only disposes the ones that where not re-used above.
+    _recognizers = newRecognizers;
+  }
+
+  void _disposeRecognizers() {
+    if (_recognizers != null) {
+      for (final GestureRecognizer recognizer in _recognizers!.values) {
+        recognizer.dispose();
+      }
+      _recognizers = null;
+    }
+  }
+
+  // ---- HitTestTarget ----
+
+  @override
+  void handleEvent(PointerEvent event, HitTestEntry entry) {
+    if (event is PointerDownEvent &&
+        configuration.recognizerFactories.isNotEmpty) {
+      if (_recognizers == null) {
+        _syncRecognizers();
+      }
+      assert(_recognizers != null);
+      for (final GestureRecognizer recognizer in _recognizers!.values) {
+        recognizer.addPointer(event);
+      }
+    }
+  }
+
+  // ---- MouseTrackerAnnotation ----
+
+  @override
+  MouseCursor get cursor => configuration.cursor;
+
+  @override
+  PointerEnterEventListener? get onEnter => configuration.onEnter;
+
+  @override
+  PointerExitEventListener? get onExit => configuration.onExit;
+
+  @override
+  bool get validForMouseTracker => true;
+
+  @override
+  String toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) {
+    return 'Span, leadingOffset: $leadingOffset, extent: $extent';
+  }
+}