Quick and dirty: add {rvg} drawings

[JanMarvin]

Using rvg examples it is possible to embed these drawings into openxlsx2. This brings editable R plots to openxlsx2.

See an example below. It is a quick and dirty implementation just to demonstrate the possibility.

library(openxlsx2)
library(ggplot2)
library(rvg)

tmp <- tempfile(fileext = ".xml")

## rvg example
dml_xlsx( file =  tmp, fonts = list(sans = "Bradley Hand"))
ggplot(data = iris,
       mapping = aes(x = Sepal.Length, y = Petal.Width)) +
  geom_point() + labs(title = "With font Bradley Hand") +
  theme_minimal(base_family = "sans", base_size = 18)
dev.off()

# include it into openxlsx2
wb <- wb_workbook()$add_worksheet() 
wb$worksheets_rels <- "<Relationship Id=\"rId1\" Type=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships/drawing\" Target=\"../drawings/drawing1.xml\"/>"
wb$drawings[[1]] <- read_xml(tmp, pointer = FALSE)
wb$worksheets[[1]]$drawing <- "<drawing r:id=\"rId1\"/>"
# wb$open()


## include it into openxlsx2 as onecell ancor graphic
# a one cell anchor with fixed size. Should convert this into a two cell anchor
xml <- read_xml(tmp, pointer = FALSE)
# pull out the actual drawing
grpSp <- xml_node(xml, "xdr:wsDr", "xdr:absoluteAnchor", "xdr:grpSp")
# construct a drawing starting at a specific position
xml_out <- read_xml(paste0(
  '<xdr:wsDr xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" xmlns:pic="http://schemas.openxmlformats.org/drawingml/2006/picture" xmlns:xdr="http://schemas.openxmlformats.org/drawingml/2006/spreadsheetDrawing">',
  '<xdr:oneCellAnchor>',
  '<xdr:from>',
  '<xdr:col>1</xdr:col>', # from this column
  '<xdr:colOff>0</xdr:colOff>',
  '<xdr:row>1</xdr:row>', # from this row
  '<xdr:rowOff>0</xdr:rowOff>',
  '</xdr:from>',
  '<xdr:ext cx="8000000" cy="4000000"/>', # with this size
  grpSp,
  '<xdr:clientData/>',
  '</xdr:oneCellAnchor>',
  '</xdr:wsDr>'
), pointer = FALSE)


wb <- wb_workbook()$add_worksheet() 
wb$worksheets_rels <- "<Relationship Id=\"rId1\" Type=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships/drawing\" Target=\"../drawings/drawing1.xml\"/>"
wb$drawings[[1]] <- xml_out
wb$worksheets[[1]]$drawing <- "<drawing r:id=\"rId1\"/>"
# wb$open()

The output:

[JanMarvin]

A PR including this is in #449