Question

I have a problem. I need to get gradient from Blue to Red.
My issue is this that I have a procent in double value and I need to get a
colour, whatever string or int.
Like 0% is #FF0000FF and 100% id #FFFF0000.

Answer 1

You need to do two things:

1. figure out the amount of blue and amount of red
2. Scale percents to a number between 0-255

For example:

// scale from percents to a number between 0-255
private int scale(int percents)
{
    return (percents * 255) / 100;
}

private int getColorForPercents(int percents)
{
    int red = scale(percents);
    int blue = scale(100 - percents);
    return 0xff000000 | (red << 16) | (blue);
}