Baseline position when using "at least" and "fixed" line spacing

[jsv1]

The following is the top left corner of a 8.5x11 in (= 51x66 pc) page with 0.5 in (= 3 pc) margins, created in InDesign. The font is Liberation Serif 12 pt (= 1 pc); the line spacing (aka tracking) is 18 pt (= 1.5 pc):

The same with horizontal guidelines, there are 18 pt between them:

The same in Writer. The measurement units are set to picas; the line spacing is 1.5 pc “at least”:

Line spacing is 1.5 pc “fixed”:

Now let’s compare them:

^{ID stands for InDesign, LO stands for LibreOffice Writer.}

As you can see, the lines on all three examples doesn’t match each other!

It seems that while Writer aligns text lines to the bottom of their line spacing, InDesign aligns them to the top. To test this assumption, I open InDesign and change the baseline shift of the default paragraph style to -6 pt (minus 6 pt). This is because our line spacing is 18 pt and the font size is 12 pt, and 18 - 12 = 6.

Yes, my assumption was correct. You can see that now the lines in InDesign are aligned the same as the ones with fixed line-spacing in Writer:

Zoom 200%:

My questions:

1. Why does Writer line spacing with “at least” and “fixed” line spacing doesn’t look the same? Yes, I do realize that they can look differently at specific circumstances (for example, if you have 20 pt inline image). But why they are different in this particular example? It seems they should be exactly the same.

2. Is it possible to tell Writer to place its lines to the top of their line spacing, so that it won’t be necessary to shift the baseline in InDesign to have the lines in InDesign and Writer look the same?

[ajlittoz]

1. Fixed irrevocably sets the line spacing to what you forced it, without taking into consideration font metrics. At least checks that no glyph will get clipped by increasing the current line height when needed.
   You must be aware that font size as selected in document processors is not a reliable indication about the final line height. See this Wikipedia page for the various height “components”. In addition, font glyphs may have internal leading resulting in a larger bounding box than what could be inferred from the glyph itself. This is very common in the x-direction to space the characters without the need to insert dummy blocks.

2. Writer and InDesign are not targeting the same purposes.
   InDesign is used to format pages where you position “manually” your blocks inside the page. All blocks are independent from each other (some may be linked so that contents overflows in the next block of the link chain). InDesign developers may have chosen to ignore “space above” for the first line in the block.
   Writer manages a text flow and allocates pages as needed to accommodate contents. Probably to simplify matters, developers may have chosen to handle the first line like any other line, using line height and space above just like in the other lines. This involves anyhow a complex first pass on the line to compute the highest ascender height to position correctly the base line.
   So the answer to question 2 is “No, you can’t offset the base line in Writer”.

Out of curiosity: why do you need to align InDesign and Writer? To the best of my knowledge, you can’t mix bits from each suite inside a single document. Perhaps if you describe what you try to achieve, we could suggest a procedure.

[jsv1]

Out of curiosity: why do you need to align InDesign and Writer?

I have created a Writer template for my needs, and the metrics of this template (grid, line spacing and so on) are additionally, and in the visually clear way, stored in the InDesign document, which works as a reference instance. After I have discovered that these programs handle line spacing differently (InDesign prefers “top”, while Writer prefers “bottom”), I decided that it will be a good idea to understand all of the ins and outs, just in case.

Fixed irrevocably sets the line spacing to what you forced it, without taking into consideration font metrics. At least checks that no glyph will get clipped by increasing the current line height when needed.

Yes, I know, but line spacing 18 pt seems to be really enough for Liberation Serif 12 pt. So I’m not sure this is related here. The actual reason, though, might be very low-level, and only LibreOffice developers probably can answer it.

[EarnestAl]

For word-processing, the InDesign approach might cause issues. In the screenshot from inDesign below, the umlauts and accent are outside the text box (ignore the contents of the text, it was open at the time, the text size and line spacing is as you described).
In LO, the characters would be cut by the Header if they were much higher, in fact using Fixed line spacing at 12pt they are (but aren’t cut with At Least, or Single spacing).

InDesign CS5