make public function in library asynchronous.

Adds initial workings of a function to save image to stream in library.

DeathSocket/Domain.fs

@@ -4,6 +4,7 @@
     module Domain =
 
         open System.Drawing
+        open System.Drawing.Imaging
 
         type ImageSpec =
             { originalPath: string;
@@ -11,4 +12,12 @@
               colour: Brush; 
               penWidth: float32 
               rows: int;
+              columns: int }
+
+        type StreamSpec =
+            { imagePath: string;
+              format: ImageFormat;
+              colour: Brush; 
+              penWidth: float32 
+              rows: int;
               columns: int }

DeathSocket/GridPainter.fs

@@ -8,9 +8,11 @@ namespace DeathSocket
         open ImageServices
 
         let applyGrid spec =
-            try
-                validateFilePath |> ignore
-                drawGrid spec |> ignore
-            with
-            | :? FileNotFoundException as ex -> printfn"%s" ex.Message
+            async {
+                try
+                    validateFilePath |> ignore
+                    drawGrid spec |> ignore
+                with
+                | :? FileNotFoundException as ex -> printfn"%s" ex.Message
+            }
             

DeathSocket/ImageServices.fs

@@ -3,6 +3,7 @@
     open System.Drawing
     open System.Drawing.Imaging
     open DeathSocket
+    open System.IO
 
     let createHorizontalLines width height rows =
         let interval = width / rows
@@ -29,4 +30,17 @@
         img.Dispose ()
         graphics.Dispose ()
         pen.Dispose ()
-        ()
+
+    let drawGridToStream (imgStream: Stream) spec =
+        let img = Bitmap.FromFile (spec.imagePath)
+        let graphics = Graphics.FromImage img
+        let pen = new Pen (spec.colour, width = spec.penWidth)
+        let horizontalLines =
+            createHorizontalLines (img.Size.Width) (img.Size.Height) (spec.columns)
+        let verticalLines = createVerticalLines (img.Size.Height) (spec.columns)
+        for line in horizontalLines do graphics.DrawLines (pen, line)
+        for line in verticalLines do graphics.DrawLines (pen, line)
+        graphics.Dispose ()
+        pen.Dispose ()
+        img.Save (imgStream, spec.format)
+        img.Dispose ()

DeathSocket/ScratchPad.fsx

@@ -59,4 +59,4 @@ let spec =
       penWidth = float32 (10)
       rows = 10
       columns = 10 }
-GridPainter.applyGrid spec
+GridPainter.applyGrid spec |> Async.RunSynchronously