Q: How can I convert an RGB color into an index to a palette created
by my application? Color2Index converts the RGB color to an index to the current
device's color table, but that's not what I want.
A: There's no single call that will give you a palette match to an
RGB color. You'll have to do this: call Color2Index to get the closest match to your RGB
request; call Index2Color to get the device's indexed color from your match; search the palette
yourself to find the color match (according to RGB value); and call Color2Index to verify that
you have the color you're looking for.
Alternatively, you can create an off-screen GWorld, call Palette2CTab to convert your palette to
a color table, and call UpdateGWorld to insert your new color table in your off-screen GWorld. Then,
to find the index of an RGB color, make your GWorld the active device and call Color2Index.
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