Remove KnownColors static constructor

[ThomasGoulet73]

Description

Removes KnownColors static constructor and replaces it with uint parsing and calling Enum.IsDefined. The static constructor is called at the startup of every WPF app AFAIK (It is called even with an app created from the empty WPF template). The size of the dictionary at runtime is about 10 Kb so not much but it is still unnecessary used memory.

Benchmark results of KnownColors.ArgbStringToKnownColor

Method	argbString	Mean	Error	StdDev	Ratio	RatioSD	Allocated	Alloc Ratio
Old	#FFDA70D6	15.2223 ns	0.2156 ns	0.2017 ns	1.00	0.02	-	NA
New	#FFDA70D6	13.6033 ns	0.0437 ns	0.0365 ns	0.89	0.01	-	NA
Old	#XYZ	9.1676 ns	0.0399 ns	0.0353 ns	1.00	0.01	-	NA
New	#XYZ	5.4110 ns	0.0116 ns	0.0097 ns	0.59	0.00	-	NA
Old	FFDA70D6	11.5086 ns	0.0509 ns	0.0476 ns	1.00	0.01	-	NA
New	FFDA70D6	0.8499 ns	0.0034 ns	0.0028 ns	0.07	0.00	-	NA

Customer Impact

Better perf, better startup perf and lower static memory.

Regression

No.

Testing

Local testing.

Risk

Low.

Microsoft Reviewers: Open in CodeFlow

[h3xds1nz]

Faster solution can be achieved by using AlternateLookup for trimmed string and actually using StringComparer.OrdinalIgnoreCase for the dictionary itself instead of uppering it.

But that ~10 kB per app, the creation time of the dictionary, vs. 2ns gained per compare on a function that's only called during serialization; this is clearly a better solution for the case, so yeah, once again, well done, Thomas.

[ThomasGoulet73]

Faster solution can be achieved by using AlternateLookup for trimmed string and actually using StringComparer.OrdinalIgnoreCase for the dictionary itself instead of uppering it.

But that ~10 kB per app, the creation time of the dictionary, vs. 2ns gained per compare on a function that's only called during serialization; this is clearly a better solution for the case, so yeah, once again, well done, Thomas.

Yes I initially had the same thought but while working on it I found that, when comparing my current changes vs doing a more optimized dictionary lookup, my current changes were cleaner, faster (I didn't see the 2ns gain you mention) and used less memory .

But as you said, even if there was a 2ns gain by doing a more optimized lookup I think we should go with my current changes since it's cleaner and it removes the need for a 10 Kb dictionary.

[ThomasGoulet73]

I've rebased on main to add a unit test that validates my changes.

I also pushed a change to "fix" the method when argbValue is null. In reality the method is not reachable when argbValue is null because it would throw before the method is called but I wanted to keep parity with main. I only changed the thrown exception from NullReferenceException on main to ArgumentNullException with my changes. But, as I said, it's not reachable at runtime, it only affects the new unit test.

[ThomasGoulet73]

I rebased on main to fix the conflicts.

[dipeshmsft]

Thanks @ThomasGoulet73, good contribution.