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[web] Align offset for lines of rich text (#23043)

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Mouad Debbar 2020-12-14 13:23:03 -08:00 committed by GitHub
parent bbed7c6ab8
commit 8ead1df40b
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 25 additions and 5 deletions
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25
lib/web_ui/lib/src/engine/text/layout_service.dart
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@ -318,6 +318,28 @@ class LineBuilder {
bool get isEmpty => _segments.isEmpty;
bool get isNotEmpty => _segments.isNotEmpty;
/// The horizontal offset necessary for the line to be correctly aligned.
double get alignOffset {
final double emptySpace = maxWidth - width;
final ui.TextDirection textDirection =
paragraph.paragraphStyle._textDirection ?? ui.TextDirection.ltr;
final ui.TextAlign textAlign =
paragraph.paragraphStyle._textAlign ?? ui.TextAlign.start;
switch (textAlign) {
case ui.TextAlign.center:
return emptySpace / 2.0;
case ui.TextAlign.right:
return emptySpace;
case ui.TextAlign.start:
return textDirection == ui.TextDirection.rtl ? emptySpace : 0.0;
case ui.TextAlign.end:
return textDirection == ui.TextDirection.rtl ? 0.0 : emptySpace;
default:
return 0.0;
}
}
/// Measures the width of text between the end of this line and [newEnd].
double getAdditionalWidthTo(LineBreakResult newEnd) {
// If the extension is all made of space characters, it shouldn't add
@ -509,8 +531,7 @@ class LineBuilder {
hardBreak: end.isHard,
width: width + ellipsisWidth,
widthWithTrailingSpaces: widthIncludingSpace + ellipsisWidth,
// TODO(mdebbar): Calculate actual align offset.
left: 0.0,
left: alignOffset,
lineNumber: lineNumber,
);
}

5
lib/web_ui/test/text/layout_service_plain_test.dart
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@ -11,7 +11,6 @@ import 'package:ui/ui.dart' as ui;
import 'layout_service_helper.dart';
const bool skipTextAlign = true;
const bool skipWordSpacing = true;
final EngineParagraphStyle ahemStyle = EngineParagraphStyle(
@ -641,7 +640,7 @@ void testMain() async {
l('defgh', 4, 9, hardBreak: false, width: 50.0, left: 0.0),
l('i', 9, 10, hardBreak: true, width: 10.0, left: 40.0),
]);
}, skip: skipTextAlign);
});
test('handles rtl with textAlign', () {
CanvasParagraph paragraph;
@ -694,5 +693,5 @@ void testMain() async {
l('defgh', 4, 9, hardBreak: false, width: 50.0, left: 0.0),
l('i', 9, 10, hardBreak: true, width: 10.0, left: 40.0),
]);
}, skip: skipTextAlign);
});
}