create.colourkey opens new device and draws even when assigned to variable

[stefaneng]

create.colourkey is a wrapper around lattice::draw.colorkey. We have set the parameter draw = TRUE which will print the key on whatever device/page is open or open a new device. I think this is a strange forced argument and should probably be an argument to create.colourkey with the default as draw = FALSE.

Code in question: https://github.com/uclahs-cds/public-R-BoutrosLab-plotting-general/blob/main/R/create.colourkey.R#L168

See the workaround in the discussion: #139

Example

Look at the top of the heatmap. The colorkey is drawn on top when rendered via reprex but generally will often open a new device which generally means an extra file is created.

library(BoutrosLab.plotting.general);
#> Loading required package: lattice
#> Loading required package: latticeExtra
#> Loading required package: cluster
#> Loading required package: hexbin
#> Loading required package: grid
#> 
#> Attaching package: 'BoutrosLab.plotting.general'
#> The following object is masked from 'package:stats':
#> 
#>     dist

set.seed(13);
dat1 <- matrix(rnorm(100), nrow = 10, ncol = 10);
dat2 <- matrix(rnorm(100), nrow = 10, ncol = 10);

at <- seq(-3, 3, length.out = 10);
p1 <- create.heatmap(
    dat1,
    at = at,
    clustering.method = 'none',
    same.as.matrix = TRUE,
    print.colour.key = FALSE
    );

p2 <- create.heatmap(
    dat2,
    at = at,
    clustering.method = 'none',
    same.as.matrix = TRUE,
    print.colour.key = FALSE
    );

# NOTE: This is a bug in create.colourkey. Opens a null device to write the output to
# png(nullfile())
colourkey <- create.colourkey(
    x = dat1,
    at = at,
    colourkey.labels.cex = 2.5,
    placement = viewport(
        just='center',
        x = 0.5,
        y = 1,
        width = 0.5,
        height = 0.1
        )
    );

# NOTE: This is a bug in create.colourkey. Close the null device we opened
# dev.off();

filename <- tempfile('example_shared_colourkey', fileext = '.png');
create.multipanelplot(
    plot.objects = list(p1, p2),
    layout.width = 2,
    layout.height = 1,
    width = 10,
    height = 6,
    resolution = 200,
    legend = list(
        bottom = list(
            fun = colourkey
            )
        ),
    filename = filename
    );

# To ensure that width/height are maintained by github/reprex
# All this does it load and print the png we saved
grid::grid.raster(png::readPNG(filename))

^{Created on 2023-07-20 with reprex v2.0.2}