How to save a flowchart made with grid and Gmisc

What I want to do is to create a basic flowchart with R, add it to my R Markdown file and make it referencable (if possible like I did with my ggplot2 figures -> fig.cap = " " in the code chunk header).

The Flowchart:

library(grid)
library(Gmisc)

grid.newpage()

# set some parameters to use repeatedly
leftx <- .25
midx <- .5
rightx <- .75
width <- .4
gp <- gpar(fill = "lightgrey")

# create boxes
(Pharmazie <- boxGrob("Verbrauchsdaten von der\n Spitalpharmazie (Excel-Tabelle)", 
                  x=leftx, y=0.876, box_gp = gp, width = width))

(Finanzen <- boxGrob("Belegzahlen vom Ressort\n Finanzen (Excel-Tabelle)", 
                 x=rightx, y=.876, box_gp = gp, width = width))

(A <- boxGrob("Import der Daten aus Excel ins\n Microsoft Access (Datenbanksoftware)", 
          x=midx, y=0.76, box_gp = gp, width = width))

(B <- boxGrob("Zusammenführen der Informationen\n und erstellen neuer, berechneter Tabellen", 
          x=midx, y=.64, box_gp = gp, width = width))

(C <- boxGrob("Export der neu erstellten Tabellen\n in Form von Excel-Tabellen", 
          x=midx, y=.52, box_gp = gp, width = width))

(D <- boxGrob("Import der neuen Tabellen in R", 
          x=midx, y=.414, box_gp = gp, width = width))

(E <- boxGrob("Berechnung und grafische Darstellung\n der Grafiken und Tabellen", 
          x=midx, y=.308, box_gp = gp, width = width))


connectGrob(Pharmazie, A, "L")
connectGrob(Finanzen, A, "L")
connectGrob(A, B, "N")
connectGrob(B, C, "N")
connectGrob(C, D, "N")
connectGrob(D, E, "N")

The problem that I'm having is that I cannot find a way to save the flowchart to a variable / png file (to import it into my R Markdown file later) or, even better, to include it directly within a code chunk (it looks different when I execute the code within a code chunk vs. when executing it in a script, also when trying to give it a fig.cap it fails to knit).

Example of how differently it looks: .

Any help would be greatly appreciated!

P.S. I tried to make the flowchart with the package "DiagrammeR", but I gave up after I did not manage to find a way to have the text on more than one line per box (so it wouldn't be so broad).

It looks different, because the viewport you are drawing on is not the same. You just need to fiddle a bit with the positioning options to make it fit. Below I used fig.width and fig.height and created a wrapper function in which I also vertically justified the boxes (top end). This makes it easier to build the chart top to bottom using the y coordinate.

---
output: pdf_document
---


```{r echo = F, message = F, fig.width=7, fig.height = 6}
library(grid)
library(Gmisc)

# grid.newpage()
# set some parameters to use repeatedly
leftx <- .2
midx <- .5
rightx <- .8

myBoxGrob <- function(text, ...) {
  boxGrob(label = text, bjust = "top", box_gp = gpar(fill = "lightgrey"), ...)
}

# create boxes
(Pharmazie <- myBoxGrob("Verbrauchsdaten von der\n Spitalpharmazie (Excel-Tabelle)", x=leftx, y=1, width = 0.38))
(Finanzen <- myBoxGrob("Belegzahlen vom Ressort\n Finanzen (Excel-Tabelle)", x=rightx, y=1, width = 0.38))
(A <- myBoxGrob("Import der Daten aus Excel ins\n Microsoft Access (Datenbanksoftware)", x=midx, y=0.87, width = 0.5))
(B <- myBoxGrob("Zusammenführen der Informationen\n und erstellen neuer, berechneter Tabellen", x=midx, y=.70, width = 0.5))
(C <- myBoxGrob("Export der neu erstellten Tabellen\n in Form von Excel-Tabellen", x=midx, y=.53, width = 0.5))
(D <- myBoxGrob("Import der neuen Tabellen in R", x=midx, y=.36,  width = 0.5))
(E <- myBoxGrob("Berechnung und grafische Darstellung\n der Grafiken und Tabellen", x=midx, y=.21, width = 0.5))


connectGrob(Pharmazie, A, "L")
connectGrob(Finanzen, A, "L")
connectGrob(A, B, "N")
connectGrob(B, C, "N")
connectGrob(C, D, "N")
connectGrob(D, E, "N")
```

If the flowchart is acceptable, you can scale the plot using the chunk option out.width (here =".5\\textwidth"):