webshot2 does not allow transparent tables.

[padpadpadpad]

Using flexible 0.5.10, when trying to save out a table that uses webshot2 (for bold rendering), the transparent argument does not work.

table <- data.frame(x = c(1:3), y = c(1:3)) %>%
flextable() %>%
bold(part = 'all') %>%
bg(part = 'all', bg = 'transparent')

save_as_image(table, 'table.png', webshot = 'webshot2')

[davidgohel]

I don't really know how to fix that. Table cells are transparent. I think the white is coming from the body background of the web page that is considered as white by chrome (via webshot2).

When webshot is used, it's ok, but not when webshot2 is used.

[atusy]

I guess there are nothing we can do within flextable.

The following link infers --default-background-color=0 is required.
https://bugs.chromium.org/p/chromium/issues/detail?id=689349

However, I guess webshot2 package does not have feature to specify it.

I also challenged modify the chromote package to include--default-background-color=0 by default.
https://github.com/rstudio/chromote/blob/b706e2186bab6a25b8d28935a70e7383f3afb6c2/R/chrome.R#L54
However, it conflicts with --remote-debugging-port=0.
Even if I remove --remote-debugging-port=0, I get the following error and I have no idea to fix it.

Error in launch_chrome(path, args) :
Failed to start chrome. Error: [0826/002005.878925:ERROR:viz_main_impl.cc(161)] Exiting GPU process due to errors during initialization
[0826/002006.007961:ERROR:gpu_channel_manager.cc(459)] ContextResult::kFatalFailure: Failed to create shared context for virtualization.

@wch Do you have any ideas?

[wch]

According to this, the background color probably needs to be set via the Chrome Devtools Protocol.
https://bugs.chromium.org/p/chromium/issues/detail?id=689349#c20

If you want to see if it actually works, I suggest trying first by issuing commands with Chromote. Then if that works, the changes could be brought into webshot2.

[atusy]

@wch Thanks for the comments! I'll try later.

[davidgohel]

I can confirm, this command is producing a transparent image (and if no --default-background-color=0, background is white):

/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --headless --screenshot="filename.png" --default-background-color=0 --crash-dumps-dir=tmp "http://127.0.0.1:4321/table.html"

[atusy]

Great! I'm suffering some issues with using headless chrome on Docker...
It may take some time for me to contribute.

[davidgohel]

• webshot2 does not allow transparent background.
• webshot does allow transparent background.

This can't be fixed from flextable.

[github-actions]

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