geom_point points fill opacity is lost while converting to dml

[krystian8207]

Hi @davidgohel.
Thank you for the great work you're doing here developing the package!

I realized when converting ggplots storing points to dml we may lose alpha property information.
It happens when color is unspecified but alpha is provided.

Reproducible example:

library(ggplot2)
library(rvg)

dml_file <- tempfile()
dml_pptx(file = dml_file, standalone = FALSE)

ggplot(mtcars[1, ], aes(wt, mpg)) + 
  geom_point(alpha = 0.5, size = 10) +
  labs(
    x = NULL,
    y = NULL
  ) +
  theme_minimal() +
  theme(
    panel.grid.major = element_blank(),
    panel.grid.minor = element_blank(),
    axis.text = element_blank(),
    axis.title = element_blank()
  )
dev.off()
dml_gg <- xml2::read_xml(dml_file)

xml_children(xml_child(xml_child(dml_gg, 4), 2)) %>% lapply(xml_name) %>% unlist()
[1] "xfrm"     "prstGeom" "ln"

When color is precised everything is fine, alpha can be extracted from shape's "p:spPr/a:solidFill" child.

I'd be grateful if you could take a look at it. Thank you.

sessionInfo():

R version 4.1.0 (2021-05-18)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 20.04.2 LTS

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3
LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/liblapack.so.3

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8   
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

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

other attached packages:
 [1] ggtext_0.1.2       gslideR_0.0.0.9000 gdtools_0.2.4      magrittr_2.0.3     xml2_1.3.3         rvg_0.3.1          officer_0.5.0     
 [8] ggimage_0.3.1      ggplot2_3.4.0      googleAuthR_2.0.0 

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.9          lattice_0.20-45     assertthat_0.2.1    rprojroot_2.0.3     digest_0.6.31       utf8_1.2.2         
 [7] R6_2.5.1            httr_1.4.4          pillar_1.8.1        ggfun_0.0.9         yulab.utils_0.0.6   rlang_1.0.6        
[13] curl_4.3.3          uuid_1.1-0          rstudioapi_0.14     magick_2.7.3        Matrix_1.5-3        desc_1.4.2         
[19] labeling_0.4.2      splines_4.1.0       stringr_1.5.0       munsell_0.5.0       gridtext_0.1.5      compiler_4.1.0     
[25] httpuv_1.6.7        xfun_0.36           pkgconfig_2.0.3     systemfonts_1.0.4   gridGraphics_0.5-1  mgcv_1.8-41        
[31] tibble_3.1.8        fansi_1.0.3         withr_2.5.0         later_1.3.0         commonmark_1.8.1    rgoogleslides_0.3.2
[37] nlme_3.1-161        jsonlite_1.8.4      gtable_0.3.1        lifecycle_1.0.3     scales_1.2.1        zip_2.2.2          
[43] stringi_1.7.8       cli_3.5.0           cachem_1.0.6        farver_2.1.1        renv_0.15.4         fs_1.5.2           
[49] promises_1.2.0.1    vctrs_0.5.1         tools_4.1.0         ggplotify_0.1.0     glue_1.6.2          markdown_1.4       
[55] purrr_1.0.0         pkgload_1.3.2       fastmap_1.1.0       colorspace_2.0-3    gargle_1.2.1        memoise_2.0.1