Java swing. How to change color intensity from black to white?

Question

I don't see the how to change color only from black to white. Grayscale.

My example. I have values that goes from 0 to 100.

Their representation is like this:

0 - Black

100 - White

I am painting JComponent and whenever I have to change color I have to call

g.setColor(Color);

But how to tell it to change color only from Black to White, depending of my number (the larger the number, color is whiter)? How to manipulate over RGB?

Answer 1

There is, of course, no color change from black to white, per se, except through gradually lighter shades of gray.

So, just use equal values of RGB, treating 0 - 100 as a percentage of 255.

For example, 50% is RGB of 128,128,128 (though depending on rounding you might arrive at 127,127,127).

The expression for going from a percentage value to a 0-255 is:

rgb=(pct*255)/100;

Answer 2

The Color API has HSB values which you may find easier to use.

You can also use the HSL Colors. Check out the "luminance" tab when you start with a black or white color.

Answer 3

As long as values are equal in rgb you have a grey.

so

g.setColor(new Color(0, 0, 0);

is white.

g.setColor(new Color(255,255,255);

is black

g.setColor(new Color(128,128,128);

is an equal blend of white and black.