Fix Texture2D.FromStream support for 1bit PNGs

[tomspilman]

Ran across a 1bpp PNG image that our existing Texture2D.FromStream would not load.

We should add this format to the unit tests and ensure it works.

You can download this white 1bpp texture here:

https://user-images.githubusercontent.com/103522/31480817-aafc0bde-aee5-11e7-9cb5-77491b4d3ae2.png

[KonajuGames]

As raised back in #2424 and with @rds1983's StbSharp library, I'll have a go at integrating the StbSharp code into MonoGame (to avoid the extra assembly).

[tomspilman]

I'll have a go at integrating the StbSharp code into MonoGame (to avoid the extra assembly).

I suggest making StbSharp the default for all platform except consoles for now.

Then remove all our old image loading code.

[KonajuGames]

That's the plan.

[rds1983]

Maybe I misunderstood the discussion, but wanted to say that StbSharp is already integrated in the MG: https://github.com/MonoGame/MonoGame/tree/develop/MonoGame.Framework/Utilities/Imaging
It is used for Texture2D.FromStream only for the DesktopGL version. And it seems to load fine the image attached to this ticket.

[KonajuGames]

I did remember it had been done, but didn't find it. Probably because of the Utilities/Imaging directory. I'll extend the DesktopGL version of Texture2D.FromStream to all platforms.

[KonajuGames]

STB doesn't support TIF or DDS. Do we consider that much a loss? XNA supported PNG, JPG, GIF. STB supports PNG, JPG, GIF, BMP, PSD, TGA plus others that never get used in the real world.

[KonajuGames]

Added PR #6008 to fix this and use StbSharp for all implementations of Texture2D.FromStream(GraphicsDevice, Stream). More details in the PR description.

[KonajuGames]

@rds1983 If you update your StbSharp library, we could use ImageWriter for Texture2D.SaveAsJpg() and Texture2D.SaveAsPng() since JPG support has been added to stb_image_write.h back in March.

[rds1983]

I think SaveAsPng already uses StbSharp, while SaveAsJpg uses TinyJpeg:

MonoGame/MonoGame.Framework/Graphics/Texture2D.OpenGL.cs

Line 459 in f726fb6

internal void SaveAsImage(Stream stream, int width, int height, ImageWriterFormat format)

However I'll surely port latest stb_image_write.h as it'll allow to drop TinyJpeg.