[Rd] grid stringHeight

[Paul Murrell]

Hi

This is a basic "feature" of both strheight() and stringHeight().  They 
both ignore any descenders in the text.  I cannot remember why it was 
done this way originally.  The future solution is probably to add an 
argument that allows descenders to be included in text height.

Plotmath works on bounding boxes so its behaviour is different, but of 
course that has its own problems because there is no sense of "baseline" 
for expressions.

Paul

On 27/04/2011 11:06 a.m., baptiste auguie wrote:
> Dear all,
>
> I'm puzzled by the behavior of stringHeight in the grid package.
> Consider the following test,
>
> library(grid)
>
> test<- function(lab="dog", ...){
>    g1<- textGrob(lab)
>    g2<- rectGrob(height=grobHeight(g1), width=grobWidth(g1))
>    gg<- gTree(children=gList(g1,g2), ...)
>
>    print(c("height:", convertUnit(stringHeight(lab), "mm", "y")))
>    grid.draw(gg)
> }
>
> grid.newpage()
> test()
> test(expression(dog), vp=viewport(x=0.6))
> ## notice how the dog's tail is being cut off, where
> ## expression yields a snug cage
>
> grid.newpage()
> test("aoc")
> test(expression(aoc), vp=viewport(x=0.6))
>
> It appears that stringHeight correctly calculates the height for an
> expression, but not for a basic string. I think it used to produce the
> same output for both.
>
> Best regards,
>
> baptiste
>
> sessionInfo()
> R version 2.13.0 alpha (2011-03-27 r55076)
> Platform: i386-apple-darwin9.8.0 (32-bit)
>
> locale:
> [1] C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  grid      methods
> [8] base
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/