Okay, not really about audio, nor about dsp. But related to creating UI's for it.
I've pushed out a CairoColorPicker app which could pick a color from anywhere on screen (or from a Color circle) and put out the values as Cairo rgba data, or as True Color RGB data, or, as html notation. For RGB and html the alpha channel will be respected for a white background.
nevertheless here you go:
https://github.com/brummer10/CairoColorPicker
as like all my last work it is licensed under the free BSD0 license.
ColorPicker
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