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Fix getOffsetForCaret to return correct value if contains widget span (#98542)

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chunhtai 2022-02-22 12:29:22 -08:00 committed by GitHub
parent 9dc9cf57f2
commit fd41d419b4
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 26 additions and 4 deletions
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5
packages/flutter/lib/src/painting/placeholder_span.dart
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@ -41,6 +41,9 @@ abstract class PlaceholderSpan extends InlineSpan {
TextStyle? style,
}) : super(style: style);
/// The unicode character to represent a placeholder.
static const String placeholderCodeUnit = '\uFFFC';
/// How the placeholder aligns vertically with the text.
///
/// See [ui.PlaceholderAlignment] for details on each mode.
@ -57,7 +60,7 @@ abstract class PlaceholderSpan extends InlineSpan {
@override
void computeToPlainText(StringBuffer buffer, {bool includeSemanticsLabels = true, bool includePlaceholders = true}) {
if (includePlaceholders) {
buffer.write('\uFFFC');
buffer.write(placeholderCodeUnit);
}
}

4
packages/flutter/lib/src/painting/text_painter.dart
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@ -739,7 +739,7 @@ class TextPainter {
// Get the Rect of the cursor (in logical pixels) based off the near edge
// of the character upstream from the given string offset.
Rect? _getRectFromUpstream(int offset, Rect caretPrototype) {
final String flattenedText = _text!.toPlainText(includePlaceholders: false);
final String flattenedText = _text!.toPlainText(includeSemanticsLabels: false);
final int? prevCodeUnit = _text!.codeUnitAt(max(0, offset - 1));
if (prevCodeUnit == null)
return null;
@ -789,7 +789,7 @@ class TextPainter {
// Get the Rect of the cursor (in logical pixels) based off the near edge
// of the character downstream from the given string offset.
Rect? _getRectFromDownstream(int offset, Rect caretPrototype) {
final String flattenedText = _text!.toPlainText(includePlaceholders: false);
final String flattenedText = _text!.toPlainText(includeSemanticsLabels: false);
// We cap the offset at the final index of the _text.
final int? nextCodeUnit = _text!.codeUnitAt(min(offset, flattenedText.length - 1));
if (nextCodeUnit == null)

3
packages/flutter/lib/src/widgets/widget_span.dart
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@ -139,7 +139,8 @@ class WidgetSpan extends PlaceholderSpan {
@override
int? codeUnitAtVisitor(int index, Accumulator offset) {
return null;
offset.increment(1);
return PlaceholderSpan.placeholderCodeUnit.codeUnitAt(0);
}
@override

18
packages/flutter/test/painting/text_painter_test.dart
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@ -37,6 +37,24 @@ void main() {
expect(caretOffset.dx, painter.width);
});
test('TextPainter caret test with WidgetSpan', () {
// Regression test for https://github.com/flutter/flutter/issues/98458.
final TextPainter painter = TextPainter()
..textDirection = TextDirection.ltr;
painter.text = const TextSpan(children: <InlineSpan>[
TextSpan(text: 'before'),
WidgetSpan(child: Text('widget')),
TextSpan(text: 'after'),
]);
painter.setPlaceholderDimensions(const <PlaceholderDimensions>[
PlaceholderDimensions(size: Size(50, 30), baselineOffset: 25, alignment: ui.PlaceholderAlignment.bottom),
]);
painter.layout();
final Offset caretOffset = painter.getOffsetForCaret(ui.TextPosition(offset: painter.text!.toPlainText().length), ui.Rect.zero);
expect(caretOffset.dx, painter.width);
}, skip: isBrowser && !isCanvasKit); // https://github.com/flutter/flutter/issues/56308
test('TextPainter null text test', () {
final TextPainter painter = TextPainter()
..textDirection = TextDirection.ltr;