smouldering-beach-ball/SmoulderingBeachBall/ImageMaker.fs

namespace SmoulderingBeachBall

module ImageMaker =

    open System
    open System.IO
    open System.Drawing

    type OverlayType =
        | Border
        | Full

    type OverlaySpec =
        { colour: Brush;
          overlayType: OverlayType }

    type ImageSpec =
        { width: int;
          height: int;
          colour: Brush;
          filePath: string;
          overlay: OverlaySpec }

    let private validateDimension dimension =
        match dimension with
        | dimension when dimension <= 0 -> invalidArg "dimension" "The width and height must be greater than 0."
        | _ -> ()

    let private validateDirectory filePath =
        let path = Path.GetDirectoryName filePath
        match (Directory.Exists path) with
        | false -> invalidArg "filePath" "Unable to save to the specified location because it does not exist."
        | true -> ()

    let makeImage width height colour filepath =
        async {
            try
                validateDimension width
                validateDimension height
                validateDirectory filepath
                use bitmap = new Bitmap(width, height)
                use graphics = Graphics.FromImage(bitmap)
                graphics.FillRectangle(colour, new Rectangle(0, 0, bitmap.Width, bitmap.Height))
                bitmap.Save(filepath)
                return "Image saved."
            with
            | :? ArgumentException as ex -> return ex.Message
            | _ as ex -> return ex.Message
        }

    let drawMainImage spec =
        use bitmap = new Bitmap(spec.width, spec.height)
        use graphics = Graphics.FromImage(bitmap)
        graphics.FillRectangle(spec.colour, new Rectangle(0, 0, bitmap.Width, bitmap.Height))
        bitmap.Save(spec.filePath)

    let makeImage2 spec = 
        async {
            try
                validateDimension spec.width
                validateDimension spec.height
                validateDirectory spec.filePath
                // add option code for overlay here
                drawMainImage spec
                return "Image saved."
            with
            | :? ArgumentException as ex -> return ex.Message
            | _ as ex -> return ex.Message
        }