add input validation to makeImage.

Add async and try-catch blocks to makeImage.
Refactor the scratch pad. script

SmoulderingBeachBall/SmoulderingBeachBall/ImageMaker.fs

@@ -2,19 +2,33 @@ namespace SmoulderingBeachBall
 
 module ImageMaker =
 
+    open System
     open System.Drawing
-    //open System.Drawing.Imaging
+    open System.IO
 
-    let addOverlay colour image =
-        null
+    let private validateDimension dimension =
+        match dimension with
+        | dimension when dimension <= 0 -> invalidArg "dimension" "The width and height must be greater than 0."
+        | _ -> ()
 
-    let saveImage filePath =
-        null
+    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: int) (height: int) (colour: Brush) =
+    let makeImage width height colour filepath =
         async {
-            use bitmap = new Bitmap(width, height)
-            use graphics = Graphics.FromImage(bitmap)
-            graphics.FillRectangle(Brushes.Coral, new Rectangle(0, 0, bitmap.Width, bitmap.Height))
-            return "we"
+            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/SmoulderingBeachBall/ScratchPad.fsx

@@ -2,14 +2,27 @@
 
 open System.Drawing
 open System.Drawing.Imaging
+open SmoulderingBeachBall
+
+// INITIAL IDEA =======================================================================================================
 
 let width = 500
 let height = 500
 let colour = Brushes.BurlyWood
+let testPath = "C:/users/craig/desktop/test.png"
 let draw () =
     use bmp = new Bitmap(width, height)
     use gr = Graphics.FromImage(bmp)
     gr.FillRectangle(colour, new Rectangle(0, 0, bmp.Width, bmp.Height))
     gr.DrawImage(bmp, 0, 0)
-    bmp.Save("C:/users/craig/desktop/test.png", ImageFormat.Png)
-let result = draw ()
+    bmp.Save(testPath, ImageFormat.Png)
+
+// IMAGE MAKER ========================================================================================================
+
+let im_width = 500
+let im_height = 500
+let im_colour = Brushes.BurlyWood
+let im_testPath = "C:/users/craig/desktop/test.png"
+
+ImageMaker.makeImage im_width im_height im_colour im_testPath
+    |> Async.RunSynchronously

SmoulderingBeachBall/SmoulderingBeachBall/SmoulderingBeachBall.fsproj

@@ -6,18 +6,6 @@
 
   <ItemGroup>
     <Compile Include="ImageMaker.fs" />
-    <COMReference Include="{215d64d2-031c-33c7-96e3-61794cd1ee61}">
-      <Guid>215d64d2-031c-33c7-96e3-61794cd1ee61</Guid>
-      <VersionMajor>2</VersionMajor>
-      <VersionMinor>4</VersionMinor>
-      <WrapperTool>tlbimp</WrapperTool>
-    </COMReference>
-    <COMReference Include="{d37e2a3e-8545-3a39-9f4f-31827c9124ab}">
-      <Guid>d37e2a3e-8545-3a39-9f4f-31827c9124ab</Guid>
-      <VersionMajor>2</VersionMajor>
-      <VersionMinor>4</VersionMinor>
-      <WrapperTool>tlbimp</WrapperTool>
-    </COMReference>
     <None Include="ScratchPad.fsx" />
   </ItemGroup>