Wesner has been spending time with color,
the good old color from WinForms. Interestingly enough, there are reasons for the
odd behavior he describes...
When working on WinForms and ASP.NET we really wanted to unify some of the system
types, and color was a pretty problematic one. The issue was that ASP.NET wanted to
allow all the oddities of HTML (including the ability to use bogus or out of range
values) for color, while WinForms wanted to allow all the oddities of User and GDI+
(including system colors that represent a logical color). The solution - lets to it
all!
So the Color class was born.
We debated a lot internally if Color should be 64-bit scRGB or 32-bit RGB... in the
end GDI+ (if i recall correctly) ended up punting on full 64-bit support for color,
however we knew in the future they would want to move there. The internal data structure
of color therefore uses a 64-bit value to store the color, but only ever utalizes
the first 32-bits.
Next, to support the various ASP.NET round tripping issues, we needed to store the
string name of the color.
Finally, we have a state bit to determine what is determining the color - basically
is this a natural RGB, known color, or named color. Known colors are just the magic
colors that are part of the web and win32 built in color set (Red, ControlText, etc.).
We wanted to track the known colors both for dealing with the whacky Win32 system
colors, and to preserve the knowledge that a color was specified as "red" not as 255,0,0.
That is what we have today - a big color class that can do a lot, but has a lot of
idosyncricies...
In Avalon we are moving to a full 64-bit color engine (native scRGB support) with
support for multiple color spaces (you can specify colors in CMYK, etc.). Our color
object won't be shared by ASP.NET, so we don't have some of the name based stuff that
we have to worry about, and right now our plan is not to support Win32 system colors
- but rather to solve the same problem using our styling and resource system to have
a more natural and evolvable system instead of the magic colors.