rename Library.fs to ImageMaker.fs.

Port code from previous commits into new NuGet project.

SmoulderingBeachBall/ImageMaker.fs

@@ -0,0 +1,34 @@
+namespace SmoulderingBeachBall
+
+module ImageMaker =
+
+    open System
+    open System.Drawing
+    open System.IO
+
+    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
+        }

SmoulderingBeachBall/Library.fs

@@ -1,5 +0,0 @@
-namespace SmoulderingBeachBall
-
-module Say =
-    let hello name =
-        printfn "Hello %s" name

SmoulderingBeachBall/SmoulderingBeachBall.fsproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <Compile Include="Library.fs" />
+    <Compile Include="ImageMaker.fs" />
   </ItemGroup>
 
 </Project>