Save image as PNG in Shiny with a download button

[sumanthmutte]

Hi @swsoyee ,
I have been trying to export the image generated through m_png() through a download button in Shiny, but I am not able to get that work. I have tried png-dev.off(), png::writePNG and also htmlWidgets-webshot but none of them worked for me. They work normally in an R environment but not in a shiny app download button. Here is the corresponding code from the server section of my app.R:

expression <- {
  r3dmol( viewer_spec = m_viewer_spec(cartoonQuality = 10, lowerZoomLimit = 50, upperZoomLimit = 350) ) %>%
    # Add model to scene
    m_add_model(data = pdb_file, format = "pdb") %>%
    # Zoom to encompass the whole scene
    m_zoom_to() %>%
    # Set style of structures
    m_set_style(style = m_style_cartoon(color = "#00cc96")) %>%
    # Set style of specific selection (selecting by secondary)
    m_set_style( sel = m_sel(ss = "s"), style = m_style_cartoon(color = "#636efa", arrows = TRUE) ) %>%
    # Style the alpha helix
    m_set_style( sel = m_sel(ss = "h"), style = m_style_cartoon(color = "#ff7f0e") ) 
}

output$pdb <- renderR3dmol(expression)

data2 <- reactiveValues()

data2$imageToSave <- renderImage({
  expression %>% m_png()
  })

output$downloadImage <- downloadHandler(
  filename = "AuxPhosImage.png",
  content = function(file){ 
    png::writePNG(data2$imageToSave)
  }
  )

I am using 'pdb' and 'downloadImage' in the 'ui' part as fluidRow(column(6, align="center", downloadButton('downloadImage','Download Image'), r3dmolOutput("pdb")).

I tried the same procedure for to save a ggplot object using ggsave which worked perfectly. But I am not able to get this working. One difference that I found is that this png from r3dmol is rendered into the 'viewer' but not the 'plot' section, for which the reason the png saving options are not working I guess, I might be wrong.

Any help is highly appreciated.

Thanks, Sumanth.

[swsoyee]

I found is that this png from r3dmol is rendered into the 'viewer' but not the 'plot' section

@sumanthmutte Yes, actually the m_png() function do not create a image, it just convert the widget to a base64 png.
The easiest way to do this is to write a help text that reminds the user that they can right-click to save the results of m_png()

[sumanthmutte]

Sure. Thank you @swsoyee .