Screenshots are saves as png despite .jpg extension

[olivercoad]

Describe the bug
While looking into #499, I realised that the screenshot function saves the image in png format despite adding the .jpg file extension.

canopy/src/canopy/canopy.parallell.functions.fs

Lines 52 to 99 in a593649

	let private saveScreenshot directory filename pic =
	if not <| Directory.Exists(directory)
	then Directory.CreateDirectory(directory) |> ignore
	IO.File.WriteAllBytes(Path.Combine(directory,filename + ".jpg"), pic)
	let private takeScreenShotIfAlertUp () =
	try
	let screenBounds = canopy.screen.getPrimaryScreenBounds ()
	let bitmap = new Bitmap(width = screenBounds.width, height = screenBounds.height, format = PixelFormat.Format32bppArgb);
	use graphics = Graphics.FromImage(bitmap)
	graphics.CopyFromScreen(screenBounds.x, screenBounds.y, 0, 0, screenBounds.size, CopyPixelOperation.SourceCopy);
	use stream = new MemoryStream()
	bitmap.Save(stream, ImageFormat.Png)
	stream.Close()
	stream.ToArray()
	with ex ->
	printfn "Sorry, unable to take a screenshot. An alert was up, and the backup plan failed!
	Exception: %s" ex.Message
	Array.empty<byte>
	let private takeScreenshot directory filename (browser : IWebDriver) =
	try
	let pic = (browser :?> ITakesScreenshot).GetScreenshot().AsByteArray
	saveScreenshot directory filename pic
	pic
	with
	| :? UnhandledAlertException as ex->
	let pic = takeScreenShotIfAlertUp()
	saveScreenshot directory filename pic
	let alert = browser.SwitchTo().Alert()
	alert.Accept()
	pic
	let private pngToJpg pngArray =
	let pngStream = new MemoryStream()
	let jpgStream = new MemoryStream()
	pngStream.Write(pngArray, 0, pngArray.Length)
	let img = Image.FromStream(pngStream)
	img.Save(jpgStream, ImageFormat.Jpeg)
	jpgStream.ToArray()
	(* documented/actions *)
	let screenshot directory filename (browser : IWebDriver) =
	match box browser with
	| :? ITakesScreenshot -> takeScreenshot directory filename browser |> pngToJpg
	| _ -> Array.empty<byte>

Unfortunately, I don't think fixing this won't help reduce file size for #499 because failure screenshots uses the returned byte array which is actually converted to jpg format.

To Reproduce
Steps to reproduce the behavior:

1. Take a screenshot

start chrome
url "https://github.com/lefthandedgoat/canopy/issues/500"
screenshot "screenshots" "issue500"

2. Check the file format. For example in linux (or WSL),

$ file screenshot/issue500.jpg
issue500.jpg: PNG image data, 824 x 918, 8-bit/color RGBA, non-interlaced

Expected behavior
Should convert to jpg before saving the file. Or save with .png file extension.

Other information

• OS: Windows 10
• Browser: chrome
• NETCore 3.1
• canopy 2.1.5

Dotnet core
screenshot actually fails when I use dotnet core. It saves the png format file (with .jpg extension) and then throws when trying to convert to jpg. Maybe I'm missing a paket reference or something.

System.PlatformNotSupportedException: System.Drawing is not supported on this platform.
   at System.Drawing.Image.FromStream(Stream stream)
   at canopy.parallell.functions.pngToJpg(Byte[] pngArray) in C:\projects\canopy\src\canopy\canopy.parallell.functions.fs:line 89
   at <StartupCode$FSI_0013>.$FSI_0013.main@()

[lefthandedgoat]

I can fix this this weekend. canopy uses https://www.nuget.org/packages/System.Drawing.Common/ which should work with .net core but I will also try it on windows + osx, no linux vm handy sorry.

[IvanRainbolt]

I think my issue is related here from comparing the error messages. My script is here:
https://gist.github.com/IvanRainbolt/42b8c0c7fe3742e741e40373582be86e
and my error message is this:
D:\OneDrive\T\canopy.experiment>fsi tryscreenshot.fsx
READY_
Starting ChromeDriver 84.0.4147.30 (48b3e868b4cc0aa7e8149519690b6f6949e110a8-refs/branch-heads/4147@{#310}) on port 65077
Only local connections are allowed.
Please see https://chromedriver.chromium.org/security-considerations for suggestions on keeping ChromeDriver safe.
ChromeDriver was started successfully.
DevTools listening on ws://127.0.0.1:65080/devtools/browser/0185cedf-d3a3-49d7-a520-81494d7584b7
path: C:\Users\netaz\AppData\Roaming\canopy
System.TypeLoadException: Could not load type 'System.MarshalByRefObject' from assembly 'System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
at canopy.parallell.functions.pngToJpg(Byte[] pngArray)
at <StartupCode$FSI_0001>.$FSI_0001.main@() in D:\OneDrive\T\canopy.experiment\tryscreenshot.fsx:line 46
Stopped due to error
D:\OneDrive\T\canopy.experiment>