Draw bullets/circles on an Image given image coordinates

问题

Hi I have a R shiny app displaying an image. I would like to draw a bullets/circles on an image based on image coordinates. The image coordinates are being read from a data frame where I would like to iterate over every row, plot and then remove the coordinates drawn for every iteration.

I have something like this now

#UI
UI <- function(id) {
fluidPage(
useShinyjs(),

fluidRow(
  column(width=12,
         box(title='Select', width = NULL, closable = TRUE,
                 actionButton("draw", "draw"))
  )),

fluidRow(width=7,
         align="center",
         box(title='Draw', width=7, height = NULL,
             imageOutput("sample")
             )
         )
  )
}
#server
Server <-function(input, output, session) {
 useShinyjs()

#loop to iterate over every x,y coordinate value in data frame
 for(i in 1:nrow(data))
{
    x = data[i,1]
    y = data[i,2]
    #how do I draw these coordinates values on the below displayed image and clear 
    #the drawn figures every iteration something like addCircles() and clearShapes() in 
    #leafletProxy() used for drawing figures on maps
}
 observeEvent(input$draw, {
 output$sample<--renderImage({
 list(src = "www/data/test.png",
      contentType = 'image/png',
      width = 700,
      height = 400)
  }, deleteFile = FALSE
  )
 }

Note: My original image is 1920x1080 and the image coordinates are accoding to these dimensions and I want to display the image in the app with custom width and height, like I have above(700x400).

来源：https://stackoverflow.com/questions/58153218/draw-bullets-circles-on-an-image-given-image-coordinates