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@wilinz
Forked from schultek/selection_transformer.dart
Last active August 19, 2023 06:40
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A widget that transforms the text selection when copied.
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
typedef SelectionTransform = String Function(Iterable<String>);
/// A widget that transforms the text selection when copied.
///
/// This uses the [SelectionContainer] with a custom [SelectionContainerDelegate] to override the
/// [getSelectedContent] method with a custom implementation.
///
/// Use this by wrapping a subtree under [SelectionArea], e.g:
/// ```dart
/// SelectionArea(
/// child: SelectionTransformer.separated(
/// child: Column(children: [
/// Text("Hello"),
/// Text("World"),
/// ]),
/// ),
/// )
/// ```
class SelectionTransformer extends StatefulWidget {
const SelectionTransformer({super.key, required this.transform, required this.child});
/// A [SelectionTransformer] that adds a separator string between each child selections.
SelectionTransformer.separated({super.key, String separator = '\n', required this.child})
: transform = _separatedSelectionTransform(separator);
/// A [SelectionTransformer] that lays out the child selection in a tabular layout.
///
/// As an example, take a widget subtree that produces the following child selections
/// (e.g. using the [Table] widget):
///
/// 'Url', 'example.com', 'Status', '404', 'Body', 'Not Found'
///
/// The tabular transformer with a column count of 2 would produce the following output:
///
/// Url example.com
/// Status 404
/// Body Not Found
///
SelectionTransformer.tabular({super.key, required int columns, required this.child})
: transform = _tabularSelectionTransform(columns);
static SelectionTransform _separatedSelectionTransform(String separator) =>
(selections) => selections.join(separator);
static SelectionTransform _tabularSelectionTransform(int columns) => (selections) {
var maxColumnWidths = List.filled(columns - 1, 0);
for (var (i, s) in selections.indexed) {
for (var j = 0; j < columns - 1; j++) {
if (i % columns == j && s.length > maxColumnWidths[j]) {
maxColumnWidths[j] = s.length;
}
}
}
var buffer = StringBuffer();
for (var (i, s) in selections.indexed) {
var j = i % columns;
if (j < columns - 1) {
buffer.write('${s.padRight(maxColumnWidths[j])}\t');
} else {
buffer.write(s);
if (i < selections.length - 1) {
buffer.write('\n');
}
}
}
return buffer.toString();
};
final SelectionTransform transform;
final Widget child;
@override
State<StatefulWidget> createState() => SelectionTransformerState();
}
class SelectionTransformerState extends State<SelectionTransformer> {
late final delegate = SeparatedSelectionContainerDelegate(transform);
String transform(Iterable<String> selections) {
return widget.transform(selections);
}
@override
void dispose() {
delegate.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return SelectionContainer(
delegate: delegate,
child: widget.child,
);
}
}
class SeparatedSelectionContainerDelegate extends MultiSelectableSelectionContainerDelegate {
SeparatedSelectionContainerDelegate(this.transform);
final SelectionTransform transform;
@override
SelectedContent? getSelectedContent() {
final List<SelectedContent> selections = <SelectedContent>[];
for (final Selectable selectable in selectables) {
final SelectedContent? data = selectable.getSelectedContent();
if (data != null) {
selections.add(data);
}
}
if (selections.isEmpty) {
return null;
}
return SelectedContent(
plainText: transform(selections.map((s) => s.plainText)),
);
}
// START: Copied from [_SelectableRegionContainerDelegate]
// Needed as [MultiSelectableSelectionContainerDelegate] does not provide a
// default implementation for [ensureChildUpdated].
final Set<Selectable> _hasReceivedStartEvent = <Selectable>{};
final Set<Selectable> _hasReceivedEndEvent = <Selectable>{};
Offset? _lastStartEdgeUpdateGlobalPosition;
Offset? _lastEndEdgeUpdateGlobalPosition;
@override
void remove(Selectable selectable) {
_hasReceivedStartEvent.remove(selectable);
_hasReceivedEndEvent.remove(selectable);
super.remove(selectable);
}
void _updateLastEdgeEventsFromGeometries() {
if (currentSelectionStartIndex != -1) {
final Selectable start = selectables[currentSelectionStartIndex];
final Offset localStartEdge =
start.value.startSelectionPoint!.localPosition + Offset(0, -start.value.startSelectionPoint!.lineHeight / 2);
_lastStartEdgeUpdateGlobalPosition = MatrixUtils.transformPoint(start.getTransformTo(null), localStartEdge);
}
if (currentSelectionEndIndex != -1) {
final Selectable end = selectables[currentSelectionEndIndex];
final Offset localEndEdge =
end.value.endSelectionPoint!.localPosition + Offset(0, -end.value.endSelectionPoint!.lineHeight / 2);
_lastEndEdgeUpdateGlobalPosition = MatrixUtils.transformPoint(end.getTransformTo(null), localEndEdge);
}
}
@override
SelectionResult handleSelectAll(SelectAllSelectionEvent event) {
final SelectionResult result = super.handleSelectAll(event);
for (final Selectable selectable in selectables) {
_hasReceivedStartEvent.add(selectable);
_hasReceivedEndEvent.add(selectable);
}
// Synthesize last update event so the edge updates continue to work.
_updateLastEdgeEventsFromGeometries();
return result;
}
/// Selects a word in a selectable at the location
/// [SelectWordSelectionEvent.globalPosition].
@override
SelectionResult handleSelectWord(SelectWordSelectionEvent event) {
final SelectionResult result = super.handleSelectWord(event);
if (currentSelectionStartIndex != -1) {
_hasReceivedStartEvent.add(selectables[currentSelectionStartIndex]);
}
if (currentSelectionEndIndex != -1) {
_hasReceivedEndEvent.add(selectables[currentSelectionEndIndex]);
}
_updateLastEdgeEventsFromGeometries();
return result;
}
@override
SelectionResult handleClearSelection(ClearSelectionEvent event) {
final SelectionResult result = super.handleClearSelection(event);
_hasReceivedStartEvent.clear();
_hasReceivedEndEvent.clear();
_lastStartEdgeUpdateGlobalPosition = null;
_lastEndEdgeUpdateGlobalPosition = null;
return result;
}
@override
SelectionResult handleSelectionEdgeUpdate(SelectionEdgeUpdateEvent event) {
if (event.type == SelectionEventType.endEdgeUpdate) {
_lastEndEdgeUpdateGlobalPosition = event.globalPosition;
} else {
_lastStartEdgeUpdateGlobalPosition = event.globalPosition;
}
return super.handleSelectionEdgeUpdate(event);
}
@override
void dispose() {
_hasReceivedStartEvent.clear();
_hasReceivedEndEvent.clear();
super.dispose();
}
@override
SelectionResult dispatchSelectionEventToChild(Selectable selectable, SelectionEvent event) {
switch (event.type) {
case SelectionEventType.startEdgeUpdate:
_hasReceivedStartEvent.add(selectable);
ensureChildUpdated(selectable);
case SelectionEventType.endEdgeUpdate:
_hasReceivedEndEvent.add(selectable);
ensureChildUpdated(selectable);
case SelectionEventType.clear:
_hasReceivedStartEvent.remove(selectable);
_hasReceivedEndEvent.remove(selectable);
case SelectionEventType.selectAll:
case SelectionEventType.selectWord:
break;
case SelectionEventType.granularlyExtendSelection:
case SelectionEventType.directionallyExtendSelection:
_hasReceivedStartEvent.add(selectable);
_hasReceivedEndEvent.add(selectable);
ensureChildUpdated(selectable);
}
return super.dispatchSelectionEventToChild(selectable, event);
}
@override
void ensureChildUpdated(Selectable selectable) {
if (_lastEndEdgeUpdateGlobalPosition != null && _hasReceivedEndEvent.add(selectable)) {
final SelectionEdgeUpdateEvent synthesizedEvent = SelectionEdgeUpdateEvent.forEnd(
globalPosition: _lastEndEdgeUpdateGlobalPosition!,
);
if (currentSelectionEndIndex == -1) {
handleSelectionEdgeUpdate(synthesizedEvent);
}
selectable.dispatchSelectionEvent(synthesizedEvent);
}
if (_lastStartEdgeUpdateGlobalPosition != null && _hasReceivedStartEvent.add(selectable)) {
final SelectionEdgeUpdateEvent synthesizedEvent = SelectionEdgeUpdateEvent.forStart(
globalPosition: _lastStartEdgeUpdateGlobalPosition!,
);
if (currentSelectionStartIndex == -1) {
handleSelectionEdgeUpdate(synthesizedEvent);
}
selectable.dispatchSelectionEvent(synthesizedEvent);
}
}
@override
void didChangeSelectables() {
if (_lastEndEdgeUpdateGlobalPosition != null) {
handleSelectionEdgeUpdate(
SelectionEdgeUpdateEvent.forEnd(
globalPosition: _lastEndEdgeUpdateGlobalPosition!,
),
);
}
if (_lastStartEdgeUpdateGlobalPosition != null) {
handleSelectionEdgeUpdate(
SelectionEdgeUpdateEvent.forStart(
globalPosition: _lastStartEdgeUpdateGlobalPosition!,
),
);
}
final Set<Selectable> selectableSet = selectables.toSet();
_hasReceivedEndEvent.removeWhere((Selectable selectable) => !selectableSet.contains(selectable));
_hasReceivedStartEvent.removeWhere((Selectable selectable) => !selectableSet.contains(selectable));
super.didChangeSelectables();
}
// END: Copied from [_SelectableRegionContainerDelegate]
}
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
typedef SelectionTransform = String Function(Iterable<String>);
/// A widget that transforms the text selection when copied.
///
/// This uses the [SelectionContainer] with a custom [SelectionContainerDelegate] to override the
/// [getSelectedContent] method with a custom implementation.
///
/// Use this by wrapping a subtree under [SelectionArea], e.g:
/// ```dart
/// SelectionArea(
/// child: SelectionTransformer.separated(
/// child: Column(children: [
/// Text("Hello"),
/// Text("World"),
/// ]),
/// ),
/// )
/// ```
class SelectionTransformer extends StatefulWidget {
const SelectionTransformer({super.key, required this.transform, required this.child});
/// A [SelectionTransformer] that adds a separator string between each child selections.
SelectionTransformer.separated({super.key, String separator = '\n', required this.child})
: transform = _separatedSelectionTransform(separator);
/// A [SelectionTransformer] that lays out the child selection in a tabular layout.
///
/// As an example, take a widget subtree that produces the following child selections
/// (e.g. using the [Table] widget):
///
/// 'Url', 'example.com', 'Status', '404', 'Body', 'Not Found'
///
/// The tabular transformer with a column count of 2 would produce the following output:
///
/// Url example.com
/// Status 404
/// Body Not Found
///
SelectionTransformer.tabular({super.key, required int columns, required this.child})
: transform = _tabularSelectionTransform(columns);
static SelectionTransform _separatedSelectionTransform(String separator) =>
(selections) => selections.join(separator);
static SelectionTransform _tabularSelectionTransform(int columns) {
return (selections) {
var maxColumnWidths = List<int>.filled(columns - 1, 0);
var indexedSelections = selections.toList().asMap().entries;
for (var entry in indexedSelections) {
var i = entry.key;
var s = entry.value;
for (var j = 0; j < columns - 1; j++) {
if (i % columns == j && s.length > maxColumnWidths[j]) {
maxColumnWidths[j] = s.length;
}
}
}
var buffer = StringBuffer();
for (var entry in indexedSelections) {
var i = entry.key;
var s = entry.value;
var j = i % columns;
if (j < columns - 1) {
buffer.write('${s.padRight(maxColumnWidths[j])}\t');
} else {
buffer.write(s);
if (i < indexedSelections.length - 1) {
buffer.write('\n');
}
}
}
return buffer.toString();
};
}
final SelectionTransform transform;
final Widget child;
@override
State<StatefulWidget> createState() => SelectionTransformerState();
}
class SelectionTransformerState extends State<SelectionTransformer> {
late final delegate = SeparatedSelectionContainerDelegate(transform);
String transform(Iterable<String> selections) {
return widget.transform(selections);
}
@override
void dispose() {
delegate.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return SelectionContainer(
delegate: delegate,
child: widget.child,
);
}
}
class SeparatedSelectionContainerDelegate extends MultiSelectableSelectionContainerDelegate {
SeparatedSelectionContainerDelegate(this.transform);
final SelectionTransform transform;
@override
SelectedContent? getSelectedContent() {
final List<SelectedContent> selections = <SelectedContent>[];
for (final Selectable selectable in selectables) {
final SelectedContent? data = selectable.getSelectedContent();
if (data != null) {
selections.add(data);
}
}
if (selections.isEmpty) {
return null;
}
return SelectedContent(
plainText: transform(selections.map((s) => s.plainText)),
);
}
// START: Copied from [_SelectableRegionContainerDelegate]
// Needed as [MultiSelectableSelectionContainerDelegate] does not provide a
// default implementation for [ensureChildUpdated].
final Set<Selectable> _hasReceivedStartEvent = <Selectable>{};
final Set<Selectable> _hasReceivedEndEvent = <Selectable>{};
Offset? _lastStartEdgeUpdateGlobalPosition;
Offset? _lastEndEdgeUpdateGlobalPosition;
@override
void remove(Selectable selectable) {
_hasReceivedStartEvent.remove(selectable);
_hasReceivedEndEvent.remove(selectable);
super.remove(selectable);
}
void _updateLastEdgeEventsFromGeometries() {
if (currentSelectionStartIndex != -1) {
final Selectable start = selectables[currentSelectionStartIndex];
final Offset localStartEdge =
start.value.startSelectionPoint!.localPosition + Offset(0, -start.value.startSelectionPoint!.lineHeight / 2);
_lastStartEdgeUpdateGlobalPosition = MatrixUtils.transformPoint(start.getTransformTo(null), localStartEdge);
}
if (currentSelectionEndIndex != -1) {
final Selectable end = selectables[currentSelectionEndIndex];
final Offset localEndEdge =
end.value.endSelectionPoint!.localPosition + Offset(0, -end.value.endSelectionPoint!.lineHeight / 2);
_lastEndEdgeUpdateGlobalPosition = MatrixUtils.transformPoint(end.getTransformTo(null), localEndEdge);
}
}
@override
SelectionResult handleSelectAll(SelectAllSelectionEvent event) {
final SelectionResult result = super.handleSelectAll(event);
for (final Selectable selectable in selectables) {
_hasReceivedStartEvent.add(selectable);
_hasReceivedEndEvent.add(selectable);
}
// Synthesize last update event so the edge updates continue to work.
_updateLastEdgeEventsFromGeometries();
return result;
}
/// Selects a word in a selectable at the location
/// [SelectWordSelectionEvent.globalPosition].
@override
SelectionResult handleSelectWord(SelectWordSelectionEvent event) {
final SelectionResult result = super.handleSelectWord(event);
if (currentSelectionStartIndex != -1) {
_hasReceivedStartEvent.add(selectables[currentSelectionStartIndex]);
}
if (currentSelectionEndIndex != -1) {
_hasReceivedEndEvent.add(selectables[currentSelectionEndIndex]);
}
_updateLastEdgeEventsFromGeometries();
return result;
}
@override
SelectionResult handleClearSelection(ClearSelectionEvent event) {
final SelectionResult result = super.handleClearSelection(event);
_hasReceivedStartEvent.clear();
_hasReceivedEndEvent.clear();
_lastStartEdgeUpdateGlobalPosition = null;
_lastEndEdgeUpdateGlobalPosition = null;
return result;
}
@override
SelectionResult handleSelectionEdgeUpdate(SelectionEdgeUpdateEvent event) {
if (event.type == SelectionEventType.endEdgeUpdate) {
_lastEndEdgeUpdateGlobalPosition = event.globalPosition;
} else {
_lastStartEdgeUpdateGlobalPosition = event.globalPosition;
}
return super.handleSelectionEdgeUpdate(event);
}
@override
void dispose() {
_hasReceivedStartEvent.clear();
_hasReceivedEndEvent.clear();
super.dispose();
}
@override
SelectionResult dispatchSelectionEventToChild(Selectable selectable, SelectionEvent event) {
switch (event.type) {
case SelectionEventType.startEdgeUpdate:
_hasReceivedStartEvent.add(selectable);
ensureChildUpdated(selectable);
break;
case SelectionEventType.endEdgeUpdate:
_hasReceivedEndEvent.add(selectable);
ensureChildUpdated(selectable);
break;
case SelectionEventType.clear:
_hasReceivedStartEvent.remove(selectable);
_hasReceivedEndEvent.remove(selectable);
break;
case SelectionEventType.selectAll:
case SelectionEventType.selectWord:
break;
case SelectionEventType.granularlyExtendSelection:
case SelectionEventType.directionallyExtendSelection:
_hasReceivedStartEvent.add(selectable);
_hasReceivedEndEvent.add(selectable);
ensureChildUpdated(selectable);
break;
}
return super.dispatchSelectionEventToChild(selectable, event);
}
@override
void ensureChildUpdated(Selectable selectable) {
if (_lastEndEdgeUpdateGlobalPosition != null && _hasReceivedEndEvent.add(selectable)) {
final SelectionEdgeUpdateEvent synthesizedEvent = SelectionEdgeUpdateEvent.forEnd(
globalPosition: _lastEndEdgeUpdateGlobalPosition!,
);
if (currentSelectionEndIndex == -1) {
handleSelectionEdgeUpdate(synthesizedEvent);
}
selectable.dispatchSelectionEvent(synthesizedEvent);
}
if (_lastStartEdgeUpdateGlobalPosition != null && _hasReceivedStartEvent.add(selectable)) {
final SelectionEdgeUpdateEvent synthesizedEvent = SelectionEdgeUpdateEvent.forStart(
globalPosition: _lastStartEdgeUpdateGlobalPosition!,
);
if (currentSelectionStartIndex == -1) {
handleSelectionEdgeUpdate(synthesizedEvent);
}
selectable.dispatchSelectionEvent(synthesizedEvent);
}
}
@override
void didChangeSelectables() {
if (_lastEndEdgeUpdateGlobalPosition != null) {
handleSelectionEdgeUpdate(
SelectionEdgeUpdateEvent.forEnd(
globalPosition: _lastEndEdgeUpdateGlobalPosition!,
),
);
}
if (_lastStartEdgeUpdateGlobalPosition != null) {
handleSelectionEdgeUpdate(
SelectionEdgeUpdateEvent.forStart(
globalPosition: _lastStartEdgeUpdateGlobalPosition!,
),
);
}
final Set<Selectable> selectableSet = selectables.toSet();
_hasReceivedEndEvent.removeWhere((Selectable selectable) => !selectableSet.contains(selectable));
_hasReceivedStartEvent.removeWhere((Selectable selectable) => !selectableSet.contains(selectable));
super.didChangeSelectables();
}
// END: Copied from [_SelectableRegionContainerDelegate]
}
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