custom_inputs_lessonfive.R

# Try to remove the input Handler as shiny does not allow double input
# handlers
try({ removeInputHandler("DoubleColorPickerBinding") })

# Use the shiny registerInputHandler function to
# register a way to deal with the inputs coming
shiny::registerInputHandler(
  "DoubleColorPickerBinding", 
  function(x, shinysession, name) {
    
    if(is.null(x)) {
      return(x)
      
    } else {
      # Parse return value from JSON into R format dataframe
      colors_df <- jsonlite::fromJSON(x)
      
      # Extract the values of the data frame as a list
      res <- list()  
    
      res[["fill"]] <- colors_df$value[
        which(grepl(colors_df$name,pattern="fill"))
        ]
      res[["border"]] <- colors_df$value[
        which(grepl(colors_df$name,pattern="border"))
        ]
      
      return(res)
    }
  }
)