add text height calculation for multiline text area

[outofambit]

(As previously noted in #5366)

We support vertical alignment of text with textAlign(), but right now the vertical height for multiline text is not computed. This means that a single line text is vertically aligned properly, but not multiline text.

It might be tricky to calculate the total height of multiline text because the text wrap style will change how many lines of text are laid out.

https://editor.p5js.org/outofambit/sketches/eqIUrqXH6 would demonstrate this issue, but won't render until we release a version of p5.js with the bug fix in #5366.

[dhowe]

[dhowe]

can someone help double-check these alignments?

[dhowe]

NOTES:

1. seems vertical 'baseline' and 'top' are identical when a width is specified, which appears to be the case in existing reference tests as well.

2. I have changed the algorithm so that spaces are not included on the right edge of right-aligned text, which I believe is correct, but is a change from previous behavior.

3. When comparing with images generated from Processing (in test/manual-test-examples/p5.font), one will notice different leading. This is due to how leading is computed when textSize but not textLeading is called:

      Processing (top): (textAscent() + textDescent()) * 1.275f;
      p5.js (bottom):    textSize * 1.25

[outofambit]

hey @dhowe thanks so much for doing this! i was going to say all the examples look right but i wasn't sure about baseline vs center but it seems you've figured that out. :) For the leading question, i think we might want to fix that, but that doesn't need to happen as part of this fix. (i just checked and the behavior your're showing is the same on the main branch.) so i think this is good as-is!

[dhowe]

Cool. If I remember correctly the different manner of calculating leading was a group decision made at the time as it yielded better results, but certainly open to re-discussing.

[dhowe]

also @outofambit perhaps you have a preference, one way or the other, regarding #5408 ...

[outofambit]

fixed with #5432!