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Trying to Learn Details of Grid Graphics, Help Page Errors

3 messages · biii m@iii@g oii de@@ey@ws, Paul Murrell

biii m@iii@g oii de@@ey@ws
# 
Hello,

 

I'm trying to learn the details of grid graphics.  Specifically, I'm trying
to create a check that will give a warning or error if text goes outside of
the visible plot area.  (See
https://github.com/tidyverse/ggplot2/issues/3282 for an example of what I
mean.)

 

In my digging, I think that the right way to do this will be to add either a
drawDetails, preDrawDetails, or postDrawDetails method for the "text" class.
My questions are:  Is that the right way to do it or should I be looking
elsewhere?  Or, is there already a way to do this?

 

As I was digging in and trying to learn how to do it, I tried to follow some
of the examples from the help page for drawDetails (?drawDetails).  But, the
suggested functions to review do not exist.  Specifically, I wanted to look
at grid:::preDrawDetails.frame mentioned in the second paragraph of the
Details section of the help page, and it doesn't exist.
grid:::drawDetails.xaxis and grid:::postDrawDetails.frame also do not exist
(mentioned in the next two paragraphs).

 

I would try to make patch, but there is no preDrawDetails or postDrawDetails
method in grid that has any content.  For drawDetails, there are many
choices, and since I'm learning, I'm not sure which would be the best to use
as an example.

 

Thanks,

 

Bill
Paul Murrell
# 
Hi

The first place you should probably start (given where you are right 
now) is this R Journal article ...

https://journal.r-project.org/archive/2013/RJ-2013-035/RJ-2013-035.pdf

In brief, the drawDetails() function has been (almost entirely) 
superceded by the makeContent() function.

The best overall reference is probably the "R Graphics" book (3rd 
edition, chapts 6, 7, & 8).  Unfortunately, because the first edition 
came out in 2005, that is an Olde Worlde pay-for-a-print-version book 
(and probably will be until something stupid like 50 years after I have 
gone).  Or maybe you are lucky and work for a first-world university 
that has purchased access to an electronic version.

Thanks for pointing out the problems with the drawDetails() help page; I 
will need to fix that.

Paul
On 9/23/2021 2:21 AM, bill at denney.ws wrote:

  
    

      
      
    

  


  


      

    

    
1 day later

    

      
      

        


  

        

      biii m@iii@g oii de@@ey@ws
    

    

      
      #
    

  


  

      
Hi Paul,

Thanks very much for the pointer!

With that and a bit more investigation, I was able to make the following
functions that seem to work in initial testing.

Thanks,

Bill

library(grid)

# The no_clipping function indicates if a shape is clipped in any dimension
# relative to the entire device.  It should work for any rectangular shaped
# grob.
no_clipping <- function(x) {
  # Check the cardinal directions and corners to allow for any rotation
  angles <- seq(0, 3.5, by=0.5)*90
  if ("rot" %in% names(x)) {
    # At least text grobs have a "rot" attribute
    angles <- angles + (x$rot*pi/180)
  }
  edges_raw <-
    grid::deviceLoc(
      x=grid::grobX(x, theta=angles),
      y=grid::grobY(x, theta=angles)
    )
  edges <-
    list(
      x=grid::convertX(edges_raw$x, unitTo="cm", valueOnly=TRUE),
      y=grid::convertY(edges_raw$y, unitTo="cm", valueOnly=TRUE)
    )
  d_size <- dev.size(units="cm")
  c(
    bottom=0 <= min(edges$y),
    top=max(edges$y) <= d_size[2],
    left=0 <= min(edges$x),
    right=max(edges$x) <= d_size[1]
  )
}

makeContent.text <- function(x) {
  if (!all(no_clipping(x))) {
    warning(
      "Graphics text is outside of the device: ",
      paste0("'", x$label, "'", collapse=", ")
    )
  }
  x
}

Code I used for testing:

graphics.off()
foo <- grid.text(label="foo bar", x=0.95, y=0.9)
no_clipping(foo)
graphics.off()
foo <- grid.text(label="foo bar", x=0.9, y=0.9)
no_clipping(foo)
graphics.off()
foo <- grid.text(label="foo bar", x=0.95, y=0.9, rot=45)
no_clipping(foo)
foo <- grid.text(label="foo bar", x=0.96, y=0.9, rot=45)
no_clipping(foo)
graphics.off()
foo <- grid.text(label="foo bar", x=0.96, y=0.9, rot=80)
no_clipping(foo)
graphics.off()
foo <- grid.rect(x=0.8, y=0.8, width=0.15, height=0.15, default.units="npc",
just=c(0, 0))
no_clipping(foo)
graphics.off()
vp <- viewport(angle=45)
foo <- grid.rect(x=0.8, y=0.8, width=0.15, height=0.15, default.units="npc",
just=c(0, 0), vp=vp)
no_clipping(foo)

# It also works with ggplot2
library(ggplot2)
data_with_long_names <-
  data.frame(
    A=c(paste0(rep(LETTERS, 3), collapse=""), "ab", paste0(rep(letters, 3),
collapse="")),
    B=1
  )

# Feature request: This gives a warning
ggplot(data_with_long_names, aes(x=A, y=B)) +
  geom_point()

ggplot(data_with_long_names, aes(x=A, y=B)) +
  geom_point() +
  theme(
    axis.text.x=element_text(angle=45, hjust=1, vjust=1, size=rel(0.5))
  )

-----Original Message-----
From: Paul Murrell <paul at stat.auckland.ac.nz> 
Sent: Wednesday, September 22, 2021 4:50 PM
To: bill at denney.ws; r-help at r-project.org
Subject: Re: [R] Trying to Learn Details of Grid Graphics, Help Page Errors

Hi

The first place you should probably start (given where you are right
now) is this R Journal article ...

https://journal.r-project.org/archive/2013/RJ-2013-035/RJ-2013-035.pdf

In brief, the drawDetails() function has been (almost entirely) superceded
by the makeContent() function.

The best overall reference is probably the "R Graphics" book (3rd edition,
chapts 6, 7, & 8).  Unfortunately, because the first edition came out in
2005, that is an Olde Worlde pay-for-a-print-version book (and probably will
be until something stupid like 50 years after I have gone).  Or maybe you
are lucky and work for a first-world university that has purchased access to
an electronic version.

Thanks for pointing out the problems with the drawDetails() help page; I
will need to fix that.

Paul

        
On 9/23/2021 2:21 AM, bill at denney.ws wrote:

            

      
      
      
    

        
"text" class.

            

      
      
      
    

        
and it doesn't exist.

            

      
      
      
    

        

      
      
    

        
--
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/