Java Generate rainbow color - how?

Question

I d like to show rainbow colors in java, so the color first time: red, then light red.. then orange light orange, yellow...etc..

How i can do this?

Which Java graphics API are you using? AWT? Swing? Something else? — thkala, Jan 26 '11 at 14:04

score 4 · Accepted Answer · answered Jan 26 '11 at 14:03

4

For rainbow colors I would suggets HSV (Hue-Saturation-Value) color space. For all rainbow colors just cycle through the hue.

answered Jan 26 '11 at 14:03

kaoD

yeah, i d like it:) any help on this? – lacas Jan 26 '11 at 14:12
Check out Color and ColorSpace classes. There's a default HSV ColorSpace defined, you just have to get its instance. – kaoD Jan 26 '11 at 14:19
1

Sadly that's not correct... The HSV model wraps around the original colour, and rainbows do not go back to red after violet (they continue with ultra-violet). – fortran Jan 28 '11 at 08:32
Good catch :) Technically that's true, but I guess he's fine with the visible spectrum. – kaoD Jan 28 '11 at 19:34

score 1 · Answer 2 · edited May 23 '17 at 12:15

A few hints:

Find a function to transform the wavelength to RGB space Convert light frequency to RGB?
Overwrite the paint function of a component
- Remap one of the coordinates (you choose x or y if you want to show the rainbow horizontally or vertically, or time if you want an animation) to visible light wavelengths.
- Paint each line http://download.oracle.com/javase/1.3/docs/api/java/awt/Graphics.html#drawLine%28int,%20int,%20int,%20int%29 (or rectangle with a width greater than 1px if you don't need the smoothest gradation) covering your component with a different colour, remapping the wavelength to RGB space.

2 Answers2