add some nullable ref types for image detection

[SimonCropp]

My plan it to tackle this as small easily reviewable PRs

given the Big Bang #2236 didnt seem to work

[JimBobSquarePants]

My plan it to tackle this as small easily reviewable PRs

Definitely the best approach.

[JimBobSquarePants]

I cannot decide what the best pattern for nullable return types should be. I feel like anything that returns a nullable type should probably use a TryXX(in, out..) pattern (though I still haven't found a nice async pattern for that)

[SimonCropp]

I feel like anything that returns a nullable type should probably use a TryXX(in, out..)

yeah. i was trying to do this in the least intrusive way

though I still haven't found a nice async pattern for that

neither have I

[SimonCropp]

happy to add some TryXX overloads. but i would prefer to do those in a new PR

[antonfirsov]

DetectFormat and FindFormatByFileExtension returning nullable is definitely OK. Edit: Actually I like the bool TryXyz pattern better.

Assuming we are 100% committed to finish #2231 for 3.0, we need to decide about the global strategy we want to take to refactor the entire API. The PR doesn't fit the approach recommended by @tocsoft's #2231 (comment) (changes a small-sub area without without step 1).

[SimonCropp]

note that the tryxxx conversation should not be happening on this pr

[JimBobSquarePants]

Thanks for this @SimonCropp and apologies for the slow response.

I'm gonna close this in favour of the more general #2282 which allows us to complete step 1 of the global approach.

Thanks again

[SimonCropp]

@JimBobSquarePants no worries at all