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[web] Use DOM to render paragraphs with letter spacing #45651

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merged 3 commits into from
Sep 13, 2023
Merged

[web] Use DOM to render paragraphs with letter spacing #45651

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55e4cd0
[web] Use DOM to render paragraphs with letter spacing
mdebbar Sep 11, 2023
8925977
add test for Thai text
mdebbar Sep 13, 2023
0ea62ea
Merge branch 'main' into canvas_letter_spacing
mdebbar Sep 13, 2023
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6 changes: 6 additions & 0 deletions lib/web_ui/lib/src/engine/text/canvas_paragraph.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -648,6 +648,12 @@ class CanvasParagraphBuilder implements ui.ParagraphBuilder {
return;
}

final double? letterSpacing = style.letterSpacing;
if (letterSpacing != null && letterSpacing != 0.0) {
_canDrawOnCanvas = false;
return;
}

final ui.TextDecoration? decoration = style.decoration;
if (decoration != null && decoration != ui.TextDecoration.none) {
_canDrawOnCanvas = false;
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19 changes: 1 addition & 18 deletions lib/web_ui/lib/src/engine/text/paint_service.dart
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Expand Up @@ -4,7 +4,6 @@

import 'package:ui/ui.dart' as ui;

import '../dom.dart';
import '../html/bitmap_canvas.dart';
import '../html/painting.dart';
import 'canvas_paragraph.dart';
Expand Down Expand Up @@ -78,23 +77,7 @@ class TextPaintService {
final EngineTextStyle style = fragment.style;

final String text = fragment.getText(paragraph);
final double? letterSpacing = style.letterSpacing;
if (letterSpacing == null || letterSpacing == 0.0) {
canvas.drawText(text, x, y,
style: style.foreground?.style, shadows: style.shadows);
} else {
// TODO(mdebbar): Implement letter-spacing on canvas more efficiently:
// https://github.com/flutter/flutter/issues/51234
double charX = x;
final int len = text.length;
for (int i = 0; i < len; i++) {
final String char = text[i];
canvas.drawText(char, charX.roundToDouble(), y,
style: style.foreground?.style,
shadows: style.shadows);
charX += letterSpacing + canvas.measureText(char).width!;
}
}
canvas.drawText(text, x, y, style: style.foreground?.style, shadows: style.shadows);

canvas.tearDownPaint();
}
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22 changes: 22 additions & 0 deletions lib/web_ui/test/html/paragraph/general_golden_test.dart
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Expand Up @@ -337,6 +337,28 @@ Future<void> testMain() async {
return takeScreenshot(canvas, bounds, 'canvas_paragraph_letter_spacing');
});

test('letter-spacing Thai', () {
final BitmapCanvas canvas = BitmapCanvas(bounds, RenderStrategy());

const String yes = '\u0e43\u0e0a\u0e48';
const String no = '\u0e44\u0e21\u0e48';

final CanvasParagraph paragraph = rich(
EngineParagraphStyle(fontFamily: 'Roboto', fontSize: 36),
(CanvasParagraphBuilder builder) {
builder.pushStyle(EngineTextStyle.only(color: blue));
builder.addText('$yes $no ');
builder.pushStyle(EngineTextStyle.only(color: green, letterSpacing: 1));
builder.addText('$yes $no ');
builder.pushStyle(EngineTextStyle.only(color: red, letterSpacing: 3));
builder.addText('$yes $no');
},
)..layout(constrain(double.infinity));
canvas.drawParagraph(paragraph, const Offset(20, 20));

return takeScreenshot(canvas, bounds, 'canvas_paragraph_letter_spacing_thai');
});

test('draws text decorations', () {
final BitmapCanvas canvas = BitmapCanvas(bounds, RenderStrategy());
final List<TextDecorationStyle> decorationStyles = <TextDecorationStyle>[
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