Return number of lines when using drawText maxWidth

[dsernst]

When using drawText()'s maxWidth option to automatically wrap text, it would be very handy to return to the number of lines used.

Then we can move other text down to accommodate multi-line text, etc.

Without this, it seems like we still need to recalculate the number of lines manually again?

[Hopding]

I would like to improve the layout/typography support of pdf-lib. What you've noted here is really one small part of a larger improvement.

For now what you'll have to do is use the breakTextIntoLines function, essentially replicating the logic that drawText used internally:

pdf-lib/src/api/PDFPage.ts

Lines 902 to 933 in 9168383

	const wordBreaks = options.wordBreaks || this.doc.defaultWordBreaks;
	const textWidth = (t: string) => font.widthOfTextAtSize(t, fontSize);
	const lines =
	options.maxWidth === undefined
	? lineSplit(cleanText(text))
	: breakTextIntoLines(text, wordBreaks, options.maxWidth, textWidth);
	const encodedLines = new Array(lines.length) as PDFHexString[];
	for (let idx = 0, len = lines.length; idx < len; idx++) {
	encodedLines[idx] = font.encodeText(lines[idx]);
	}
	const graphicsStateKey = this.maybeEmbedGraphicsState({
	opacity: options.opacity,
	blendMode: options.blendMode,
	});
	const contentStream = this.getContentStream();
	contentStream.push(
	...drawLinesOfText(encodedLines, {
	color: options.color ?? this.fontColor,
	font: fontKey,
	size: fontSize,
	rotate: options.rotate ?? degrees(0),
	xSkew: options.xSkew ?? degrees(0),
	ySkew: options.ySkew ?? degrees(0),
	x: options.x ?? this.x,
	y: options.y ?? this.y,
	lineHeight: options.lineHeight ?? this.lineHeight,
	graphicsState: graphicsStateKey,
	}),
	);

I've added this to the roadmap for tracking: #998.

And ofc I'm happy to review PRs and/or offer proposal feedback if anybody is interested in working on this 😄.