helper function for files produced with html_print

[timelyportfolio]

I think a very useful helper function with webshot would be something that provides the valid url for a local file created with htmltools::html_print. I doubt this works on non-Windows but something like this might be very helpful especially with htmlwidgets (see ramnathv/htmlwidgets#95).

library(leaflet)
library(htmltools)
library(webshot)

tagList(
  tags$h1( 'Leaflet Map for Screenshot' )
  ,leaflet() %>% addTiles() %>% fitBounds(0, 40, 10, 50)
) %>%
  html_print %>%
  # get forward slash on windows
  normalizePath(.,winslash="/") %>%
  # replace drive:/ with drive:// so C:/ becomes C://
  gsub(x=.,pattern = ":/",replacement="://") %>%
  # appends file:/// to make valid uri
  paste0("file:///",.) %>%
  # screenshot it for lots of good reasons
  webshot( file = "stream_screen.png", delay = 3 )

[timelyportfolio]

@wch is this worth exploring/demonstrating in webshot or would it fit better in htmlwidgets?

[yihui]

This has been (almost) done in the current master branch of yihui/knitr. Simply try an arbitrary widget in R Markdown, and compile it to a non-HTML output format:

leaflet() %>% addTiles() %>% fitBounds(0, 40, 10, 50)

I have not supported arbitrary HTML objects (such as tagList()), though. See more info at https://github.com/yihui/knitr/blob/master/NEWS.md

[yihui]

Oh I forgot to mention that requires this branch of htmlwidgets: ramnathv/htmlwidgets#191

[timelyportfolio]

Great, I'll check it out there and close this issue here. I only used tagList to ease html_print. Thanks!

[wch]

I can see how this might be useful outside of knitr as well.

@timelyportfolio I think that this functionality would conceptually be a nice fit for inclusion in htmlwidgets. However, because webshot has some unusual external dependencies, it could make sense to include that functionality in the webshot package itself.

[yihui]

Definitely agree this can be useful outside knitr.

[timelyportfolio]

Ok, happy to work something up, but know quest for CRAN might push it to next release. Let me know if you want to squeeze it in and I'll be glad to work on it.

[wch]

Yup, I just submitted to CRAN so it would have to be for the next version.
:)

On Thu, Mar 3, 2016 at 4:44 PM, timelyportfolio [email protected]
wrote:

Ok, happy to work something up, but know quest for CRAN might push it to
next release. Let me know if you want to squeeze it in and I'll be glad to
work on it.

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