[Rd] tcltk image reading problem (on a mac?): [tcl] encountered an unsupported criticial chunk type "eXIf"

[Simon Urbanek]

Ah, thanks, Brian, so the issue is that Catalina is now embedding Exif tags while previous versions didn’t. Tcltk never supported them, but it only came up now as Catalina is generating them. I’ll check if tcltk has ever fixed it.

Sent from my iPhone

> On 12 Jun 2020, at 19:00, Prof Brian Ripley <ripley using stats.ox.ac.uk> wrote:
> 
>> On 12/06/2020 03:49, Fox, John wrote:
>> Dear Simon,
>>> On Jun 11, 2020, at 9:00 PM, Simon Urbanek <simon.urbanek using r-project.org> wrote:
>>> 
>>> Wayne,
>>> 
>>> that one is unrelated, but interesting - you can fix it with
>>> 
>>> sudo install_name_tool -change \
>>>  /usr/local/lib:/opt/X11/lib/libtk8.6.dylib \
>>>  /usr/local/lib/libtk8.6.dylib \
>>>  /usr/local/bin/wish8.6
>>> 
>>> There is a bug in tcltk with IDs on the libraries which I have worked-around for R, but not for wish.
>>> 
>>> Back to the original question - do you have any example of a file that doesn't work so I could test? Exif chunks are fairly rare in PNG and are a more late extension so I couldn't find any examples.
>> The code in Wayne's original message (copied below) generated the offending file:
>> library(tcltk)
>> fname <- "Rplot.png"
>> png(filename = fname, width = 500, height = 500)
>> hist(rnorm(20))
>> dev.off()
>> tkimage.create("photo", file = fname)
> 
> There are several png() devices for R.  The default on macOS is to use Quartz, and that depends on macOS system functions so might well have changed with Mojave -> Catalina.
> 
> As a workaround, try e.g. png(type='cairo').  E.g.
> 
> fname <- file.path(tempdir(), "Rplot.png")
> png(filename = fname, width = 500, height = 500, type="cairo")
> hist(rnorm(20))
> dev.off()
> 
> library(tcltk)
> tkimage.create("photo", file = fname)
> 
> works for me on Catalina.
> 
> 
> -- 
> Brian D. Ripley,                  ripley using stats.ox.ac.uk
> Emeritus Professor of Applied Statistics, University of Oxford
>