HTML and string serializer doesn't support underline styles and color

[Tyriar]

xterm.js/addons/xterm-addon-serialize/src/SerializeAddon.ts

Lines 264 to 271 in 7460782

	if (cell.isInverse() !== oldCell.isInverse()) { sgrSeq.push(cell.isInverse() ? 7 : 27); }
	if (cell.isBold() !== oldCell.isBold()) { sgrSeq.push(cell.isBold() ? 1 : 22); }
	if (cell.isUnderline() !== oldCell.isUnderline()) { sgrSeq.push(cell.isUnderline() ? 4 : 24); }
	if (cell.isBlink() !== oldCell.isBlink()) { sgrSeq.push(cell.isBlink() ? 5 : 25); }
	if (cell.isInvisible() !== oldCell.isInvisible()) { sgrSeq.push(cell.isInvisible() ? 8 : 28); }
	if (cell.isItalic() !== oldCell.isItalic()) { sgrSeq.push(cell.isItalic() ? 3 : 23); }
	if (cell.isDim() !== oldCell.isDim()) { sgrSeq.push(cell.isDim() ? 2 : 22); }
	if (cell.isStrikethrough() !== oldCell.isStrikethrough()) { sgrSeq.push(cell.isStrikethrough() ? 9 : 29); }

xterm.js/addons/xterm-addon-serialize/src/SerializeAddon.ts

Lines 626 to 633 in 913cb25

	if (cell.isInverse()) { content.push('color: #000000; background-color: #BFBFBF;'); }
	if (cell.isBold()) { content.push('font-weight: bold;'); }
	if (cell.isUnderline()) { content.push('text-decoration: underline;'); }
	if (cell.isBlink()) { content.push('text-decoration: blink;'); }
	if (cell.isInvisible()) { content.push('visibility: hidden;'); }
	if (cell.isItalic()) { content.push('font-style: italic;'); }
	if (cell.isDim()) { content.push('opacity: 0.5;'); }
	if (cell.isStrikethrough()) { content.push('text-decoration: line-through;'); }

How it's handled in dom renderer:

xterm.js/src/browser/renderer/dom/DomRendererRowFactory.ts

Lines 171 to 187 in 913cb25

	if (cell.isUnderline()) {
	charElement.classList.add(`${UNDERLINE_CLASS}-${cell.extended.underlineStyle}`);
	if (charElement.textContent === ' ') {
	charElement.textContent = '\xa0'; // =  
	}
	if (!cell.isUnderlineColorDefault()) {
	if (cell.isUnderlineColorRGB()) {
	charElement.style.textDecorationColor = `rgb(${AttributeData.toColorRGB(cell.getUnderlineColor()).join(',')})`;
	} else {
	let fg = cell.getUnderlineColor();
	if (this._optionsService.rawOptions.drawBoldTextInBrightColors && cell.isBold() && fg < 8) {
	fg += 8;
	}
	charElement.style.textDecorationColor = colors.ansi[fg].css;
	}
	}
	}

[jerch]

Sidenote - same with OSC8 link handling.

[Tyriar]

👉 #4531