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

[Wayne Oldford]

Thanks everyone for getting a solution.

Brian's solution works for me too. 

Thanks again!!

Wayne


-----Original Message-----
From: Prof Brian Ripley <ripley using stats.ox.ac.uk>
Date: Friday, June 12, 2020 at 3:00 AM
To: "Fox, John" <jfox using mcmaster.ca>, Simon Urbanek <simon.urbanek using r-project.org>
Cc: Wayne Oldford <rwoldford using uwaterloo.ca>, "r-devel using r-project.org" <r-devel using R-project.org>
Subject: Re: [Rd] tcltk image reading problem (on a mac?): [tcl] encountered an unsupported criticial chunk type "eXIf"

    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