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// Copyright 2014 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.
// Flutter code sample for [SelectionContainer].
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
static const String _title = 'Flutter Code Sample';
@override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: SelectionArea(
child: Scaffold(
appBar: AppBar(title: const Text(_title)),
body: Center(
child: SelectionAllOrNoneContainer(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: const <Widget>[
Text('Row 1'),
Text('Row 2'),
Text('Row 3'),
],
),
),
),
),
),
);
}
}
class SelectionAllOrNoneContainer extends StatefulWidget {
const SelectionAllOrNoneContainer({
super.key,
required this.child
});
final Widget child;
@override
State<StatefulWidget> createState() => _SelectionAllOrNoneContainerState();
}
class _SelectionAllOrNoneContainerState extends State<SelectionAllOrNoneContainer> {
final SelectAllOrNoneContainerDelegate delegate = SelectAllOrNoneContainerDelegate();
@override
void dispose() {
delegate.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return SelectionContainer(
delegate: delegate,
child: widget.child,
);
}
}
class SelectAllOrNoneContainerDelegate extends MultiSelectableSelectionContainerDelegate {
Offset? _adjustedStartEdge;
Offset? _adjustedEndEdge;
bool _isSelected = false;
// This method is called when newly added selectable is in the current
// selected range.
@override
void ensureChildUpdated(Selectable selectable) {
if (_isSelected) {
dispatchSelectionEventToChild(selectable, const SelectAllSelectionEvent());
}
}
@override
SelectionResult handleSelectWord(SelectWordSelectionEvent event) {
// Treat select word as select all.
return handleSelectAll(const SelectAllSelectionEvent());
}
@override
SelectionResult handleSelectionEdgeUpdate(SelectionEdgeUpdateEvent event) {
final Rect containerRect = Rect.fromLTWH(0, 0, containerSize.width, containerSize.height);
final Matrix4 globalToLocal = getTransformTo(null)..invert();
final Offset localOffset = MatrixUtils.transformPoint(globalToLocal, event.globalPosition);
final Offset adjustOffset = SelectionUtils.adjustDragOffset(containerRect, localOffset);
if (event.type == SelectionEventType.startEdgeUpdate) {
_adjustedStartEdge = adjustOffset;
} else {
_adjustedEndEdge = adjustOffset;
}
// Select all content if the selection rect intercepts with the rect.
if (_adjustedStartEdge != null && _adjustedEndEdge != null) {
final Rect selectionRect = Rect.fromPoints(_adjustedStartEdge!, _adjustedEndEdge!);
if (!selectionRect.intersect(containerRect).isEmpty) {
handleSelectAll(const SelectAllSelectionEvent());
} else {
super.handleClearSelection(const ClearSelectionEvent());
}
} else {
super.handleClearSelection(const ClearSelectionEvent());
}
return SelectionUtils.getResultBasedOnRect(containerRect, localOffset);
}
@override
SelectionResult handleClearSelection(ClearSelectionEvent event) {
_adjustedStartEdge = null;
_adjustedEndEdge = null;
_isSelected = false;
return super.handleClearSelection(event);
}
@override
SelectionResult handleSelectAll(SelectAllSelectionEvent event) {
_isSelected = true;
return super.handleSelectAll(event);
}
}