边缘测试.

library(shiny)
library(ggplot2)

js <- '
async function getImageBlobFromUrl(url) {
  const fetchedImageData = await fetch(url);
  const blob = await fetchedImageData.blob();
  return blob;
}
$(document).ready(function () {
  $("#copybtn").on("click", async () => {
    const src = $("#plotDF>img").attr("src");
    try {
      const blob = await getImageBlobFromUrl(src);
      await navigator.clipboard.write([
        new ClipboardItem({
          [blob.type]: blob
        })
      ]);
      alert("Image copied to clipboard!");
    } catch (err) {
      console.error(err.name, err.message);
      alert("There was an error while copying image to clipboard :/");
    }
  });
});
'

ui <- fluidPage(
  tags$head(
    tags$script(HTML(js))
  ),
  br(),
  actionButton("copybtn", "Copy", icon = icon("copy"), class = "btn-primary"),
  br(),
  plotOutput("plotDF")
)

server <- function(input, output, session){
  
  output[["plotDF"]] <- renderPlot({
    ggplot(
      iris, aes(x = Sepal.Length, y = Sepal.Width)
    ) + geom_point()
  })
  
}

shinyApp(ui, server)

EDIT

alert 不好.我建议改为shinyToastify英镑.

library(shiny)
library(shinyToastify)
library(ggplot2)

js <- '
async function getImageBlobFromUrl(url) {
  const fetchedImageData = await fetch(url);
  const blob = await fetchedImageData.blob();
  return blob;
}
$(document).ready(function () {
  $("#copybtn").on("click", async () => {
    const src = $("#plotDF>img").attr("src");
    try {
      const blob = await getImageBlobFromUrl(src);
      await navigator.clipboard.write([
        new ClipboardItem({
          [blob.type]: blob
        })
      ]);
      Shiny.setInputValue("success", true, {priority: "event"});
    } catch (err) {
      console.error(err.name, err.message);
      Shiny.setInputValue("failure", true, {priority: "event"});
    }
  });
});
'

ui <- fluidPage(
  tags$head(
    tags$script(HTML(js))
  ),
  useShinyToastify(),
  br(),
  actionButton("copybtn", "Copy", icon = icon("copy"), class = "btn-primary"),
  br(),
  plotOutput("plotDF")
)

server <- function(input, output, session){
  
  output[["plotDF"]] <- renderPlot({
    ggplot(
      iris, aes(x = Sepal.Length, y = Sepal.Width)
    ) + geom_point()
  })
  
  observeEvent(input[["success"]], {
    showToast(
      session,
      input,
      text = tags$span(
        style = "color: white; font-size: 20px;", "Image copied!"
      ),
      type = "success",
      position = "top-center",
      autoClose = 3000,
      pauseOnFocusLoss = FALSE,
      draggable = FALSE,
      style = list(
        border = "4px solid crimson",
        boxShadow = "rgba(0, 0, 0, 0.56) 0px 22px 30px 4px"
      )
    )
  })

  observeEvent(input[["failure"]], {
    showToast(
      session,
      input,
      text = tags$span(
        style = "color: white; font-size: 20px;", "Failed to copy image!"
      ),
      type = "error",
      position = "top-center",
      autoClose = 3000,
      pauseOnFocusLoss = FALSE,
      draggable = FALSE,
      style = list(
        border = "4px solid crimson",
        boxShadow = "rgba(0, 0, 0, 0.56) 0px 22px 30px 4px"
      )
    )
  })
  
}

shinyApp(ui, server)