haskellchartshaskell-chart

Generate ByteString in Haskell-Chart

I use Haskell-Chart according to the example eample-1. Haskell-Chart generates content to file

toFile def "example1_big.png" $ do
...

Is it possible generate content of chart to ByteString instead file? I can not find a solution in the documentation.

Solution

  • Unfortunately this is not possible is a direct manner. toFile calls upon functions in the cairo library like withPDFSurface, withSVGSurface which themselves call into the cairo C-library and only take file names.

    You can always write to a temporary file and read the contents back in like this:

    import System.IO.Temp  -- from the temporary package
import qualified Data.ByteString.Char8 as BS

...
bs <- withSystemTempFile "chart-XXXXXXX" $ \path _ -> do
        toFile def path $ do ...
        BS.readFile path