Required types for System.Drawing.Color marshalling on .NET Core don't ship in-framework

[jkoritzinsky]

.NET Core's marshalling for System.Drawing.Color in COM Interop uses the System.Drawing.ColorTranslator type to convert the Color object to an OLE_COLOR value.

The System.Drawing.ColorTranslator type is forwarded from the in-box System.Drawing assembly to the OOB System.Drawing.Common assembly. As a result, the type may not always be available when marshalling a System.Drawing.Color. Additionally, the System.Drawing.ColorTranslator type is unavailable for our tests in the CoreCLR repo to use to verify behavior (which was how I discovered this issue).

cc: @AaronRobinsonMSFT

[AaronRobinsonMSFT]

cc @jeffschwMSFT

[AaronRobinsonMSFT]

@danmosemsft or @stephentoub do either of you know who would be the best to talk to about this change? Any concerns in general with moving the ColorTranslator to an in-box experience?

[danmoseley]

@safern is the person.

[safern]

Is ColorTranslator the only type we need to be inbox? If that is the case I don't mind with moving ColorTranslator to System.Drawing.Primitives (which ships in-box) and add a TypeForward for it in System.Drawing.Common

[AaronRobinsonMSFT]

@safern That is the only one we directly use. The full closure of what the ColorTranslator type needs/uses is a different story 😄

[safern]

It seems like its Closure should be Color, ColorUtil and KnownColorTable which are part of System.Drawing.Primitives, so I don't see any problem on moving it down.

[AaronRobinsonMSFT]

@safern w00t! Thank you much. Any ETA?

@jkoritzinsky What is the plan to re-enable the testing for this scenario? Will this be a pain now?

[jkoritzinsky]

Once it's in-box, testing will be really straightforward! I should be able to get it done pretty quickly!

[safern]

@safern w00t! Thank you much. Any ETA?

I'm working in various random urgent stuff. Once I get some spare time I should have this PR ready. Maybe tomorrow/monday.

[jkoritzinsky]

@safern any update on this?

[safern]

Not yet, sorry I've been with P0 stuff for infrastructure. Will try to spend some time tomorrow in this I promise 😄

[safern]

@jkoritzinsky I've been investigating a little further in what it takes to move down the type inbox to System.Drawing.Primitives and it seems like a lot more work than I thought because of the way System.Drawing.Common is structured. I wanted to know what is the scenario where this is needed since this has been like that ever since 2.0. Is this a winforms specific scenario?

I think we should just make Corelib resilient to this type being missing.

cc: @ericstj @jkotas

[ericstj]

It seems reasonable to me that CoreLib light-up on the presence of this type in its current assembly. It'll be there for WinForms. If someone building a console app wants that behavior they can add a reference to System.Drawing.Common. I think you'll need to handle the missing case anyhow since I can imagine linked / tree-shaken standalone apps may be missing all of System.Drawing.*.

[jkoritzinsky]

Office interop is another scenario where the ColorTranslator type needs to be available for the runtime to load up.