Re: Novel use of .char

[Deri]

On Sunday, 15 December 2024 23:54:08 GMT G. Branden Robinson wrote:
> Crudely, it _looks_ like the baseline might be getting shifted upward by
> the vertical dimension of the image, as if placement of the image-based
> character "knew" it needed to compensate for the implicit vertical
> motion caused by inlining it.  If so, I will be relieved, because we can
> now regard that fixup as a kludge, and take it out.  If I can find it.
> 
> But I could be wrong, and there's no policy around any of this, just a
> bunch of things that happened to work together, never got specced, and
> never got unit-tested.  :(

Hi Branden,

The string register "gnu" contains this:-

Move up : Output image from separate environment : Move right.

Comparing the difference in the grout from 1.23.0 and current, you can see two 
differences:-

@@ -73,10 +71,9 @@
 tGNU
 wh2500
 thead
-wh2500
+wx X pdf: pdfpic EXPERIMENTS/GNU-head-small.pdf
+wh30000
 V86000
-x X pdf: pdfpic EXPERIMENTS/GNU-head-small.pdf
-wh27500
 timage.
 n12000 0
 V132000

The space after the word "head" is dropped and two spaces are added after the 
image instead. Also the "move up" now occurs after the call to pdfpic.

I think this is related to your changes to \X and decisions of when to flush 
changes. The fundamental requirement for \X is that it remains in the 
chronology of the output stream. If there is a colour change before \X it 
needs to occur first, if there are word gaps before the \X, they should be 
output first. This is true for any action which changes the output, the 
chronological order of actions in a users document must be preserved in the 
grout.

Conversely .output and \! do not follow chronologically, they pass data to 
grout as soon as they are actioned, even if a partial line is being 
constructed by groff.

Cheers 

Deri