ggsave saves plots into SVG format somewhat streched

[SarenT]

SVG files generated by ggsave (tested on Ubuntu 18.04 LTS) are kind of stretched compared to the plots in RStudio or PNG format.
(R 4.0.3 ggplot2 3.3.6 svglite 2.1.0)

plot = ggplot(iris, aes(x = Species, y = Sepal.Length)) + geom_violin()
plot # RStudio
ggsave("test_ggsave.png", plot, "png")
ggsave("test_ggsave.svg", plot, "svg")

SVG files looks like this:

And the PNG file looks like this:

This is in RStudio:

I have removed the attribute lengthAdjust='spacingAndGlyphs' from text objects:

I think that this option could be the culprit.

[thomasp85]

ggsave() uses svglite to render svg. As svg files doesn't know how they are going to get rendered by default they fix the width of the string in order to make various adjustments and calculations on the string possible. This can be turned off by setting fix_text_size = FALSE in svglite()/ggsave() which effectively removes the lengthAdjust attribute you discovered

[cbrnr]

I also ran into this issue, and fix_text_size=FALSE helps. However, I noticed that the generated SVG files still differ slightly depending on which platform they were created. I compared macOS vs. Linux, and although the fonts now look identical, some of the horizontal spacing is still off. This behavior is not ideal from a reproducibility point of view, since I'd really want the SVGs to be identical and not dependent on the platform. Is there anything else I can do? Should I open a new issue? I can provide an example SVG produced on macOS and Linux.

[teunbrand]

@cbrnr Does that only happen in ggplot2 or can this be reproduced in pure grid as well?

[cbrnr]

I can try this tomorrow. Just to clarify I understand you correctly, you want me to do something like this (this is from ChatGPT)?

svglite::svglite("grid.svg", width=18, height=6, fix_text_size=FALSE)

library(grid)

grid.newpage()

set.seed(123)
n <- 30
x <- runif(n, 0.1, 0.9)
y <- runif(n, 0.1, 0.9)
groups <- sample(1:3, n, replace = TRUE)
colors <- c("red", "blue", "green")

pushViewport(viewport(width = 0.8, height = 0.8, name = "plotRegion"))
grid.rect(gp = gpar(col = "black"))  # Border around plot

for (i in 1:n) {
  grid.points(x[i], y[i], pch = 16, gp = gpar(col = colors[groups[i]]))
}

popViewport()

pushViewport(viewport(x = 0.85, y = 0.5, width = 0.2, height = 0.3, just = c("left", "center"), name = "legend"))
grid.rect(gp = gpar(col = "black"))

for (i in 1:3) {
  grid.points(0.2, 1 - i * 0.3, pch = 16, gp = gpar(col = colors[i]))
  grid.text(paste("Group", i), x = 0.5, y = 1 - i * 0.3, just = "left")
}

popViewport()
dev.off()

[cbrnr]

I should probably use svglite::svglite() though, right?

[teunbrand]

Yes, though it can be much simpler than the ChatGPT example.

library(grid)
# Try reproduce text that gave problems
x <- textGrob("my problematic label", gp = gpar(fontfamily = "Impact"))

# Write to file
svglite::svglite("example.svg", fix_text_size = FALSE)
grid.newpage(); grid.draw(x)
dev.off()

I don't have convenient access to multiple platforms so I won't be able to identify if they give different results, and/or debug the problem. But the essence is that if the problem also occurs when using pure grid, then perhaps it is a {svglite} issue instead of a {ggplot2} issue.

[cbrnr]

Thanks, I'll report back once I've tested this on multiple platforms.

[cbrnr]

However, I'll probably stick with the longer example, because text rendered identically if setting fix_text_size=FALSE (although I also find this a bit weird, because I really do want to fix text size, so I would assume that the default of TRUE would work). The entire SVG seems to be a little stretched in the x-direction (i.e., lines and positions), but not text by itself.

[cbrnr]

So I don't think this is an {svglite} issue, since the SVGs look identical if fix_text_size=FALSE. Should I open a new issue? I also think that fix_text_size=FALSE should probably be the default, since the current default of fix_text_size=TRUE stretches text depending on the platform.

Linux with fix_text_size=FALSE:

macOS with fix_text_size=FALSE:

Linux with fix_text_size=True:

macOS with fix_text_size=True: