如何在R Shiny图中使用不同的字体 [英] How to use different fonts in an R Shiny plot

问题描述

我想在Shiny中创建一个图，然后用户可以使用指定为用户输入的自定义字体将其下载为pdf.

I would like to create a plot in Shiny that the user can then download as a pdf using a custom font specified as a user input.

具体来说，我想使用pdf函数，例如pdf("plot.pdf", width = 5, height = 5, family = font.family)，其中font.family的值由用户指定.

To be specific, I would like to use a pdf function such as pdf("plot.pdf", width = 5, height = 5, family = font.family), where the value of font.family is specified by the user.

这是下面的一个简单示例:如果我在计算机上运行该示例，则可以正常工作.但是，将其托管在RStudio闪亮服务器上时，我收到一条错误消息，指出找不到指定的字体系列.我认为问题是我想要的字体无法在RStudio闪亮的服务器上访问，但是有没有办法我可以将它们包括在内?

Here is a simple example below: If I run the example on my machine, it works fine. However, when it is hosted on the RStudio shiny servers, I receive an error saying that the specified font family cannot be found. I think the problem is that the fonts I want are not accessible on the RStudio shiny servers, but is there a way I can include them?

server.R

shinyServer(function(input, output) {

output$distPlot <- renderPlot({

plot(1, xlim = c(0, 1), ylim = c(0, 1))
text(.5, .5, "Custom Font!!"
})

output$downloadPlot <- downloadHandler(

  filename = function() {paste('CustomFont.pdf')}, 
  content = function(file){

font.family <- input$font.family

pdf(file, width = 11, height= 8.5, family = font.family)

plot(1, xlim = c(0, 1), ylim = c(0, 1))
text(.5, .5, fonts(), cex = 10)


dev.off()
}, contentType = "image/pdf"
)
})

ui.R

 shinyUI(fluidPage(

 sidebarLayout(
 sidebarPanel(
  selectInput("font.family", "Choose Font", 
              choices = c("Helvetica Neue", "Times New Roman", "Arial")
  ),
  downloadButton("downloadPlot", "Download Plot as PDF")
),

# Show a plot of the plot
mainPanel(
  plotOutput("distPlot", width = "800px", height = "800px")
  ))))

推荐答案

我有 this闪亮的教程文章.字体渲染然后按预期工作.

I had a similar problem. To solve that, much of the renderPlot() functionality was recreated using renderImage(), as described in this Shiny tutorial article. Font rendering then worked as desired.

这是解决该问题的代码；也许也可以解决这个问题.

This is the code which solved that question; it might also solve this one.

ui.R修改为

mainPanel(
  imageOutput("myImage")
)

server.R

shinyServer(function(input, output, session) {

  # A dynamically-sized plot
  output$myImage <- renderImage({
    # Read myImage's width and height. These are reactive values, so this
    # expression will re-run whenever they change.
    width  <- session$clientData$output_myImage_width
    height <- session$clientData$output_myImage_height

    # For high-res displays, this will be greater than 1
    pixelratio <- session$clientData$pixelratio

    # A temp file to save the output.
    outfile <- tempfile(fileext='.png')

    # Generate the image file
    png(outfile, width=width*pixelratio, height=height*pixelratio,
        res=72*pixelratio)
    plot(rnorm(100), rnorm(100), family="serif")
    dev.off()

    # Return a list containing the filename
    list(src = outfile,
         width = width,
         height = height,
         alt = "This is alternate text")
  }, deleteFile = TRUE) # delete the temp file when finished

})

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