R devel - Sep 2007 - R-2.6.0 for Windows, semi-transparent colours and layout()

Hi,

The added support for semi-transparent colours in `windows' under 
R-2.6.0 for Windows is much appreciated.

However, I've discovered that issuing a `layout' (or `par' with 
arguments `mfcol'/`mfrow') call and then trying to plot several figures 
with semi-transparent colour on the same page results in only the first 
one being fully drawn. E.g.

 > x <- rnorm(10000)
 > y <- rnorm(10000)
 >
 > layout(matrix(1:2, ncol = 2))
 > plot(y ~ x, pch = 16, col = rgb(1, 0, 0, 0.15))
 > plot(y ~ x, pch = 16, col = rgb(1, 0, 0, 0.15))

results in the second one having only the axes and box, but no data 
points. This is under

 > sessionInfo()
R version 2.6.0 alpha (2007-09-14 r42843)
i386-pc-mingw32

locale:
LC_COLLATE=Swedish_Sweden.1252;LC_CTYPE=Swedish_Sweden.1252;LC_MONETARY=Swedish_Sweden.1252;LC_NUMERIC=C;LC_TIME=Swedish_Sweden.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base


Henric

On Sat, 15 Sep 2007, Henric Nilsson (Public) wrote:
> Hi,
>
> The added support for semi-transparent colours in `windows' under
> R-2.6.0 for Windows is much appreciated.
>
> However, I've discovered that issuing a `layout' (or `par' with
> arguments `mfcol'/`mfrow') call and then trying to plot several
figures
> with semi-transparent colour on the same page results in only the first
> one being fully drawn. E.g.
That's not the whole story, as my test examples using multiple subplots 
did work.

The problem I found is that clipping rectangles were being used in some 
places where I cannot find documentation that they should be.
So explicitly setting the clipping rectangle before each alpha-blending 
call seems to fix the problematic examples, including yours.

>
> > x <- rnorm(10000)
> > y <- rnorm(10000)
> >
> > layout(matrix(1:2, ncol = 2))
> > plot(y ~ x, pch = 16, col = rgb(1, 0, 0, 0.15))
> > plot(y ~ x, pch = 16, col = rgb(1, 0, 0, 0.15))
>
> results in the second one having only the axes and box, but no data
> points. This is under
>
> > sessionInfo()
> R version 2.6.0 alpha (2007-09-14 r42843)
> i386-pc-mingw32
>
> locale:
>
LC_COLLATE=Swedish_Sweden.1252;LC_CTYPE=Swedish_Sweden.1252;LC_MONETARY=Swedish_Sweden.1252;LC_NUMERIC=C;LC_TIME=Swedish_Sweden.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
>
> Henric
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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